Service and maintain package-type air-conditioning units (PACU) / commercial refrigeration equipment (CRE)

COMPETENCY BASED LEARNING MATERIAL

Sector:

HEATING, VENTILATING, AIR-CONDITIONING AND REFRIGERATION
(HVAC/R)

Qualification:

RAC Servicing (PACU/CRE) NC III

Unit of Competency:

Service and Maintain Package-Type Air-Conditioning Units
(PACU)/Commercial Refrigeration Equipment (CRE)

Module Title:

Servicing and Maintaining Package-Type Air-Conditioning Units
(PACU)/Commercial Refrigeration Equipment (CRE)

Technical Education and Skills Development Authority

East Service Road, South Superhighway, Taguig, Metro Manila

TABLE OF CONTENTS

.2
Introduction, Summary of Learning Outcomes and Assessment Criteria --------------------------------------- 1-4

How to use this Competency-Based Learning Material 5-6

Learning Outcome #1 Check and adjust air-conditioning and refrigeration components, controls and

operating condition------------------------------------------------------------------------------ 7

 Learning Activities-------------------------------------------------------------------------- 8

 Information Sheet #1 Maintenance and Inspection of Refrigeration and Air-

Conditioning Unit -----------------------------------------------------------------------9-13

 Job Sheet #1 Procedure for Service & Maintenance Activities ---------- 14-16

 Job Sheet #2 Cleaning Air Filters ------------------------------------------------ 17-19

 Information Sheet #2 Check and Adjust Air-Conditioning and Refrigeration

Components, Controls and Operating Condition 20-23

 Job Sheet #3 Dismantling, Inspecting, and Reassembling Service Valves

--------------------------------------------------------------------------------------------- 24-28

 Self-Check #1 ----------------------------------------------------------------------------- 29

Learning Outcome #2 Maintain Lubrication System in PACU/CRE ------------------------------------------ 30
 Learning Activities--------------------------------------------------------------------------- 31
 Information Sheet #3 Checking the Condition and Lubrication of the

Bearings ------------------------------------------------------------------------------------ 32
 Self-Check #2 ----------------------------------------------------------------------------- 33

Learning Outcome #3 Maintain Refrigeration System in PACU/CRE----------------------------------------- 34
 Learning Activities ----------------------------------------------------------------------- 35
 Information Sheet #4 Poor Condensation in PACU/CRE ----------------- 36-38
 Self-Check #3 ----------------------------------------------------------------------------- 39

Learning Outcome #4 Maintain Secondary Heat Transfer Equipment---------------------------------------- 40
 Learning Activities ---------------------------------------------------------------------- 41-43
 Information Sheet #5 Maintain Secondary Heat Transfer Equipment - 44-48
 Job Sheet #4 Test the Efficiency of a Compressor ------------------------- 49-50
 Job Sheet #5 Charge Oil in the Compressor --------------------------------- 51-52
 Job Sheet #6 Evacuate the System --------------------------------------------- 53-55
 Job Sheet #7 Charge Refrigerant in the System (Vapor Charging) ---- 56-57
 Job Sheet #8 Test Leaks in the System --------------------------------------- 58-61
 Job Sheet #9 Remove and Replace Filter Drier ----------------------------- 62-65
 Job Sheet #10 Remove and Replace Oil Separator------------------------ 66-69
 Job Sheet #11 Remove, Replace or Clean Thermostatic Expansion Valve

Strainer ---------------------------------------------------------------------------------- 70-72
 Job Sheet #12 Service Commercial Refrigerating System --------------- 73-74
 Self-Check #4 ---------------------------------------------------------------------------------

Learning Outcome #5 Maintain Air Distribution System in PACU/CRE -------------------------------------- 75
 Learning Activities------------------------------------------------------------------------ 76
 Job Sheet #13 Belt Inspection and Analysis ---------------------------------- 77-80
 Information Sheet #6 Electric Motors ------------------------------------------- 81-84
 Job Sheet #14 How to Service Motor Properly----------------------------------- 85

Competency Assessment

 Evidence Plan ----------------------------------------------------------------------------- 86
 Demonstration----------------------------------------------------------------------------- 87

Unit Service and Maintain Package-Type Air-Conditioning Units/Commercial Refrigeration Equipment

Introduction Module Servicing and Maintaining Package-Type Air-Conditioning/ Page 1

Commercial Refrigeration Units

Introduction:

This unit covers the knowledge, skills and attitudes in maintaining air-conditioning/
refrigeration components, lubrication, refrigerant, secondary heat transfer and distribution
systems in PACU /CRE units.

Summary of Learning Outcomes:

Upon completion of this module the trainee/student must be able to:

LO 1. Check and adjust air-conditioning and refrigeration components, controls and
operating condition.
LO 2. Maintain lubrication system in PACU /CRE
LO 3. Maintain refrigerant system in PACU /CRE
LO 4. Maintain secondary heat transport equipment in PACU / CRE
LO 5. Maintain air distribution system in PACU /CRE
LO 6. Maintain electrical system

Assessment Criteria:

1. Work instructions are read interpreted to determine job requirements.
2. Appropriate manufacturers manual is selected to guide maintenance procedure for

PACU/CRE.
3. Tools and equipment are selected in accordance with job requirements
4. Personal Protective Equipment [PPE] is selected in line with job requirements.
5. Evaporator /condenser coil are cleared in accordance with manufacturers maintenance

manual.
6. Refrigerant piping are checked for condition, leak, insulation, and tightness of support

/brackets
7. Operating condition and electromechanical controls/ setting is in accordance with

manufacturers operations /service manual.
8. Air-conditioning and refrigeration components are checked and adjusted as per

manufacturers operation / service manual.
9. Correct maintenance procedures are applied according to standard operating

procedures.
10. Lubrication system variables and components were checked and adjusted to meet

operational specifications
11. Oil levels, properties and circulation balances were checked and adjusted to meet

operational specifications
12. Oil leaks were detected and rectified to ensure operational efficiency
13. Recovered refrigerant in the tank must be labeled prior to recycling
14. Pressure drops across strainer, filters, and filter drier are checked and recorded.
15. Refrigerant leaks are detected and rectified to secure operational efficiency
16. Refrigerant system variables and contaminated are checked and adjusted to meet

the operational efficiency
17. Air distribution system components are checked and airflows are balanced
18. Outdoor air supply systems are checked and maintained to meet operational and

regulatory requirements
19. Humidifier, equipment is checked, serviced, and sanitized to meet operational and

regulatory requirements
20. Electrical wiring are checked for ground, continuity, open in accordance with standard

operating procedures

Unit Service and Maintain Package-Type Air-Conditioning Units/Commercial Refrigeration Equipment

Introduction Module Servicing and Maintaining Package-Type Air-Conditioning/ Page 2

Commercial Refrigeration Units

21. Electrical components, controls and devices are checked for operation and functions in
accordance with standard operating procedures.

22. Wiring connections and panels are checked for firmness and tightness in accordance
with standard operating procedures

Conditions:

The trainee must be provided with the following:

1. Learning Materials
 LEs on Maintenance methods and procedures
 Audiovisual materials on maintenance
 Audiovisual material on RAC electrical system
 Maintenance schedule

2. Training Facilities
 TV monitor
 VHS player

3. Equipment
 Pressure washer
 Audiovisual equipment
 Transport RAC unit
 Oil pump
 Acetylene equipment
 Electronic leak detector
 Aclide detector

4. Instruments
 System analyzer
 Thermometer
 Multitester
 Megger tester
 Clamp ammeter

5. Tools  Oiler
 Set of wrenches  Refrigeration ratchet
 Set of pliers  Adjustable wrench
 Set of screwdrivers  Gauge manifold
 Set of allen key wrenches  Soldering gun/iron
 Fin comb

6. Personal Protective Equipment (PPE)
 Goggles
 Gloves
 Working clothes
 Safety shoes
 Ear muff/plug

Unit Service and Maintain Package-Type Air-Conditioning Units/Commercial Refrigeration Equipment

Introduction Module Servicing and Maintaining Package-Type Air-Conditioning/ Page 3

Commercial Refrigeration Units

7. Supplies and Materials  Oil testing kits
 Refrigeration oil  Acetylene gas (contents)
 Refrigerants  Oxygen tank
 Strainer  Wax
 Filters  Electrical tape
 Filter drier  Clamp
 Soap solution  Set of screws
 Markers  Plastic cables
 Electrical tapes  Terminal clips
 Rags  Soldering lead
 Coil cleaner

References:

A. Books
 Modern Refrigeration and Air-conditioning
 Good Practice in Refrigeration Training Manual

B. Curriculum Guides
 HVAC Competency Standard
 HVAC Competency-Based Curriculum

C. Manuals

 Service Manual
 Manufacturer’s Manual

Prerequisite:

To complete this module you must have the competency in doing different benchwork
activities and maintaining tools and equipment. It is also required that you have
competence in performing good housekeeping and safety practices. If you still lack these
competencies, meet with your trainer/facilitator to determine the method you will use to
gain the said skills. One option is to review or complete the information and practice
activities in the following modules:

 Performing Basic Masonry
 Performing Mensuration and Calculation
 Performing Good Housekeeping and Safety Practices
 Installing Piping System (PACU/CRE)
 Installing Electrical System (PACU/CRE)

Contents of this Competency-Based Learning Material:

Inside this Competency-Based Learning Material are several “Learning Elements”.
Each Learning Element guides the learner to achieve one learning outcome.

Unit Service and Maintain Package-Type Air-Conditioning Units/Commercial Refrigeration Equipment

Introduction Module Servicing and Maintaining Package-Type Air-Conditioning/ Page 4

Commercial Refrigeration Units

In going through each Learning Element, you must follow the “Learning Activity
Sheet”. This Learning Activity Sheet will guide you through different “Instruction Sheets”

that will assist you in performing different learning activities towards the attainment of the

learning outcome.

 Information Sheet - This will provide you with information (concepts, principles
and other relevant information) needed in performing certain
activities.

 Operation Sheet - This will guide you in performing single task, operation or
process in a job.

 Job Sheet - This is designed to guide you on how to do the job that will
contribute to the attainment of the learning outcome.

 Assignment Sheet - The assignment sheet is a guide used to enhance (follow-up)
what you have learned in the information sheet, operation
sheet or job sheet.

 Worksheet - Worksheets are the different forms that you need to fill-up in
certain activities that you performed.

To utilize the learning material effectively, you also need to familiarize with the different
parts of the sheet.

To utilize this learning material effectively, you also need to familiarize with the different
parts of the sheet.

Title of the unit of Page number
competency
Type of sheet and
number

Information
Sheet
1

Module title Title of the sheet

The icon suggest what Content of the sheet
type of learning activity

will be done

Unit Service and Maintain Package-Type Air-Conditioning Units/Commercial Refrigeration Equipment

Introduction Module Servicing and Maintaining Package-Type Air-Conditioning/ Page 5

Commercial Refrigeration Units

How to Use this Competency-Based Learning Material

This learning material is designed to guide you in learning at your own pace. To start

with, talk with your trainer and agree on how you will both organize the training for this

module. Most probably your trainer will also be your supervisor or manager. He/she is there

to support you and guide you the correct way to do things. From time to time you will be
required to practice and demonstrate the skills that you’ve learned from this module and you
will be requiring some assistance from your trainer (as instructed in the learning material).

To proceed with the learning session you just have go through the Learning Activity
Sheet where in you will follow series of learning instructions towards attaining the learning
outcome.

For example:

The learning instruction states that you are to perform Reading Activity 1. The instruction sheet
needed is Information Sheet 1 with the title Operation of Window-type Air-conditioning Unit located at page
7 of this learning material. Below the learning instruction is a short description of the instruction sheet.
Special instructions which you may need to follow while doing this activity may also be found in this
section, if there are any.

Learning Instruction Instruction sheet type Title of the Page where the
and number instruction sheet instruction sheet is

located

This procedure should be repeatedly done until Description of the content of instruction
you have completed all the learning elements in sheet and sometimes special instructions
this Competency-Based Learning Module or until that you need to follow while performing
such time that you are ready to take the final
assessment for this module. You may skip some this learning activity
learning activities if you can demonstrate that
you are competent enough on the said task/s.

At the end part of this module is a Learner’s Diary. Use this diary to record important
dates, jobs undertaken and other workplace events that may provide further details to your
trainer or assessor. A Record of Achievement will be provided to you by your trainer for
you to accomplish once you complete the module.

Unit Service and Maintain Package-Type Air-Conditioning Units/Commercial Refrigeration Equipment

Introduction Module Servicing and Maintaining Package-Type Air-Conditioning/ Page 6

Commercial Refrigeration Units

Upon completion of this module, study the evidence plan at the end of the last learning
element of this module then ask your instructor to assess you. You will be given a certificate
of completion as proof that you met the standard requirements (knowledge, skills and
attitude) for this module. The assessment could be made in different methods, as prescribed
in the competency standards.

If you have questions, don’t hesitate to ask your instructors for assistance. Your
instructor will always be available to assist you during the training.

Recognition of Prior Learning (RPL)

You may already have some or most of the knowledge and skills covered in this module
because you have:

 been working for some time
 already completed training in this area.

If you can demonstrate to your trainer that you are competent in particular skill, talk to
him/her about having them formally recognized so you would not have to undergo the same
training again. If you have a qualification or Certificate of Competency from previous
trainings, show it to your trainer. If the skills you acquired are still current and relevant to this
module, they may become part of the evidence you can present for RPL. If you are not sure
about the level of your skills, discuss this with your trainer.

Learning Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Outcome
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 7
#1
Commercial Refrigeration Equipment

Learning Outcome # 1 : Check and adjust air-conditioning and refrigeration
components, controls and operating condition.

Assessment Criteria:

 Work instructions are read interpreted to determine job requirements.

 Appropriate manufacturers manual is selected to guide maintenance procedure for
PACU/CRE.

 Tools and equipment are selected in accordance with job requirements

 Personal Protective Equipment [PPE] is selected in line with job requirements.

 Evaporator /condenser coil are cleared in accordance with manufacturers maintenance
manual.

 Refrigerant piping are checked for condition, leak, insulation, and tightness of support
/brackets

 Operating condition and electromechanical controls/ setting is in accordance with
manufacturers operations /service manual.

 Air-conditioning and refrigeration components are checked and adjusted as per
manufacturers operation / service manual.

 Correct maintenance procedures are applied according to standard operating
procedures.

Resources:

 Refrigeration and air conditioning technology book
 Carrier owner’s manual
 Learning Element

Learning Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Outcome
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 8
#1
Commercial Refrigeration Equipment

LEARNING EXPERIENCES

LEARNING OUTCOME NO. 1: Check and adjust air-conditioning and refrigeration
components, controls and operating condition.

Learning Activities Resources

1. Read the information sheet “Maintenance  Information Sheet #1
and Inspection of Refrigeration and Air-  Job Sheet #1
Conditioning Unit.  Job Sheet #2
 Information Sheet #2
2. Read and follow the procedures in job
sheets “Procedure for Service and  Job Sheet #3
Maintenance Activities” and “Cleaning Air  Self Check #1
Filters”.

3. Read the information sheet “Check and
Adjust Air-Conditioning and Refrigeration
Components, Controls and Operating
Condition “.

4. Read and follow the procedures in job
sheet “Dismantling, Inspecting and
Reassembling Service Valves”.

5 Answer the Self-Check #1.

6. Ask instructor if you can proceed to the
next learning outcome.

Information Unit Service and Maintain Package-Type Air-Conditioning/Commercial Refrigeration Equipment
Sheet #1
Module Servicing and Maintaining Package-Type Air-Conditioning Page 9
(PACU)/ Commercial Refrigeration Equipment (CRE)

INFORMATION SHEET #1

Maintenance and Inspection of Refrigeration and Air-Conditioning Unit

In any operating refrigeration and air-conditioning unit, it is most important to provide
planned maintenance and inspection of its functioning parts to keep the units operating at its
peak efficiency.

If a unit failure occurs due to improper maintenance during the warranty period, the
manufacturer will not be liable for the cost incurred to return the unit to satisfactory operation. It
is the responsibility of the owner to assure that prescribed operating and maintenance
requirements of the units are performed as listed below.

I. Daily Requirements (Check the following):
1. Control center
 Gauges
 Indicator lights
2. Condenser and cooler units
 Temperature differential
 Pressure differential
3. Refrigerant level in cooler
4. Compressor oil level
5. Voltage
6. Verify proper water treatment

II. Weekly (Check and record the following):
1. Compressor
 Oil level
 Oil pressure
 Oil temperature
 Refrigerant suction temperature
 Refrigerant discharge temperature
2. Condenser
 Refrigerant pressure
 Refrigerant temperature
 Refrigerant high-pressure liquid temperature
 Refrigerant system air device
 Water inlet pressure
 Water inlet temperature
 Water outlet pressure
 Water outlet temperature
 Water flow rate
3. Cooler/Evaporator
 Refrigerant pressure
 Refrigerant temperature
 Refrigerant level
 Water inlet pressure
 Water inlet temperature
 Water outlet pressure
 Water outlet temperature
 Water flow rate

Information Unit Service and Maintain Package-Type Air-Conditioning/Commercial Refrigeration Equipment
Sheet #1
Module Servicing and Maintaining Package-Type Air-Conditioning Page 10
(PACU)/ Commercial Refrigeration Equipment (CRE)

4. Compressor Electric Motor
 Line voltage
 Line current
 Bearing lubrication

5. Purging Unit
 Purger pressure

6. Control Center

III. Monthly
1. Check purging unit operation, purge air and non-condensable gas if necessary.
2. Check electrical and electronic pressure and temperature controls including their safety
cut-in points and operating parameters.
3. Check, clean and tighten circuit breakers and starters controls including their terminals
and components.
4. Check and lubricate compressor motor bearing.
5. Check vibration of equipment.
6. Perform external leak test if necessary.
7. Verify proper water treatment.
8. Maintain cleanliness of equipment and its surrounding.

IV. Quarterly
1. Submit compressor lubricating oil test analysis report.
2. Check and recommend for any painting to minimize corrosion and deterioration.
3. Check and recommend for any modulation of component requirement that requires
repair or replacement.

V. Semi-annually
1. Change compressor lubricating oil
2. Change and inspect compressor oil filter element.
3. Change motor cooling refrigerant filter element.
4. Oil return system.
 Clean nozzles of oil for foreign particles
 Change filter drier dehydration or element
5. Purging unit
 Inspect and clean all valves and orifices
 Drain and flush oil refrigerant from the purger shell cylinder
 Change filter drier dehydration and foul gas strainer

VI. Annually
1. Meg and test compressor motor winding
2. Condenser and cooler
 Inspect and clean water strainer from foreign particles
 Inspect and clean tubes and end sheets (mechanical only)
 Drain and refill with water

Note: For additional information, refer to code of practice for RAC part 2.2 section 3 page 15.

Information Unit Service and Maintain Package-Type Air-Conditioning/Commercial Refrigeration Equipment
Sheet #1
Module Servicing and Maintaining Package-Type Air-Conditioning Page 11
(PACU)/ Commercial Refrigeration Equipment (CRE)

SAMPLE LOG SHEET FOR SERVICE AND MAINTAIN PACU/CRE

INSPECTION AND MAINTENANCE SCHEDULE

1. Inspect for clogging
2. Check for unusual noise or
vibration
3. Inspect keys and set screw
4. Lubricate (grease)
5. Check oil seals
6. Check oil level
7. Check oil for water and dirt
8. Change oil, at least
9. Check water level
10. Check for leakage
11. Inspect general condition
12. Tighten loose bolts
13. Clean
14. Repaint

FAN D S RR

MOTOR DSQ SSR

GEAR REDUCER DS WWM S S RR

DRIFT ELIMINATORS WR

FILL W YR

BASIN D WY S

WATER DISTRIBUTION W DY RS

STRUCTURAL Y YY R
MEMBERS

CASING WY R R

SUCTION SCREEN W W

BLOW DOWN D

D – daily, W – weekly, M – monthly, Q – quarterly, S – semi-annually, Y – yearly, R – as required

Information Unit Service and Maintain Package-Type Air-Conditioning/Commercial Refrigeration Equipment
Sheet #1
Module Servicing and Maintaining Package-Type Air-Conditioning Page 12
(PACU)/ Commercial Refrigeration Equipment (CRE)

SAMPLE LOG SHEET

Date: _________________________

Job Name: ___________________________________ Address: ______________________________________
System Model No.: ____________________________ Compressor Serial No.: ___________________________

SYSTEM DESIGN OPERATING CONDITIONS

Motor Volts ____________ Phase ____________ Hertz ___________ Speed
_____________

FLA _____________

Cooler Temperature In F ____________ Out F _____________ GPM
______________________

Pressure Drop ___________ Ft. System Refrigerant
_____________________________

Condenser Temperature In F ____________ Out F _____________ GPM
______________________

Pressure Drop ___________ Ft. System Refrigerant
_____________________________

Data By SYSTEM DATA LOG AM AM AM

Time AM PM PM PM
PM “HG. “HG. “HG.
Barometric Pressure “HG.
Suction Press. (PSI) (“HG.)
Suction Temp. FCompr.
Disch. Press. (PSI) (“HG.)
Disch. Temp. FCondenser
Pressure (PSI), (Refrigerant)
Actual Disch. Temp. F
High Press. Liquid Temp. F
Sub-cooled Liq. Temp. F
Inlet Temp. F
Outlet Temp. F
Water Press. Drop (PSI) (“HG.)

Flow

Cooler Pressure (PSI), (Refrigerant)
Actual Disch. Temp. F

Inlet Temp. F
Outlet Temp. F
Water Press. Drop (PSI) (“HG.)

Flow

Motor RPM
Volts
Amps
KW or Rev./Sec’s.

Remarks; Meter info. (Constants, size, etc.): ____________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

Information Unit Service and Maintain Package-Type Air-Conditioning/Commercial Refrigeration Equipment
Sheet #1
Module Servicing and Maintaining Package-Type Air-Conditioning Page 13
(PACU)/ Commercial Refrigeration Equipment (CRE)

Job Sheet Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
#1
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 14

Commercial Refrigeration Equipment

JOB SHEET #1

Procedure for service and maintenance activities for PACU/CRE such as:

- Mini split
- Wall mounted
- Floor mounted
- Unitary ducted
- Split ducted
- Cassette model
- Commercial refrigeration

Tools and Equipment:

Tools: Equipment:
- Set of pliers - System analyzer with hoses
- Set of screwdrivers - VOA clamp meter
- Adjustable wrench 8” - Multi-tester
- Wrench, open ½” x 9/16” - Pocket thermometer 2 pcs.
- Wrench, open 3/8” x 7/16” - Pressure washer
- Wrench, Ratchet ¼” x 3/8”
- Allen wrench (metric) 1 set Supplies:
- Paint brush 1”
Components to be serviced: - Contact cleaner
- Air filter - Laundry brush (hard)
- Evaporator coils - Liquid soap
- Control switch - Rags
- Drain lines
- AHU panels
- Condenser coils
- ACCU pan blade and motor
- Service valves
- Compressor terminals
- Magnetic contactor
- ACCU panels

Job Sheet Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
#1
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 15

Commercial Refrigeration Equipment

Procedure (Regular Servicing):

1. Turn OFF the circuit breaker.

2. Clean and check AHU.
a. Remove air filters and clean with water and soap.

3. Check drain line for clogs.

4. Return air filter properly.

5. Clean AHU panel with soft cloth and water.

6. Clean and check the ACCU.
a. Remove fan grille and electrical panel cover.
b. Check and tighten the following:
- Electrical control terminals
- Compressor terminals
- Fan motor terminals
c. Clean electrical components with paint brush

7. Clean and check the ACCU.
a. Remove fan grille and electrical panel cover
b. Check and tighten the following:
- Electrical control terminals
- Compressor terminals
- Fan motor terminals
c. Clean electrical components with paint brush

8. Switch ON the circuit breaker

9. Check unit’s operating data (Run unit for at least 15 min. before taking data.)
a. Suction line temperature
b. Ambient temperature
c. Power supply voltage
d. Compressor current draw
e. Overall current draw
f. Air in/out temperature at AHU
g. Air in/out temperature at ACCU
h. Room temperature
(Note: the suction pressure will only be taken if the unit is not cooling well after cleaning
of air filters. Otherwise, it will have to be taken to determine refrigerant charge.)

10. Clean ACCU panels with soft cloth and water.

11. Accomplish the Service Attendance Report and have it signed by the owner of his/her
authorized representative.

Job Sheet Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
#1
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 16

Commercial Refrigeration Equipment

Procedure (General Cleaning)

1. Switch off circuit breaker

2. Clean and check AHU
a. Remove air filters and clean with water and soap
b. Remove panel then check and clean the following:
- Electrical control terminals
- Blower motor terminals
- Blower wheels
c. Clean electronic control with paint brush
d. Flush drain line with pressurized water
e. Check for any signs of refrigerant leaks
f. Clean AHU coil with laundry brush
g. Return air filter and panel properly
h. Clean AHU panels with soft cloth and water

3. Clean and check the ACCU
a. Remove fan grille and electrical panel cover.
b. Check and tighten the following:
- Electrical control terminals
- Compressor terminals
- Fan motor terminals
- Fan blade and motor mounting
c. Clean electrical components with paint brush
d. Clean condenser coil using pressure washer and laundry brush.
e. Return fan grille.

4. Switch ON the circuit breaker
5. Check unit’s operating data. (See step #8 and 9 of Regular Servicing Procedures)

6. Return electrical panel cover.

7. Clean the ACCU panels with soft cloth and water.

8. Accomplish the Service Attendance Report and have it signed by the owner or his/her
authorized representative.

Job Sheet Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
#2
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 17

Commercial Refrigeration Equipment

JOB SHEET #2

CLEANING AIR FILTERS

 Filters Air filters

Option 1: Active carbon filter/Photo-catalyst filter

Option 2: Active carbon filter/Electrostatic filter

 Air filters eliminate dust and lint

 Optional active carbon filter/Photo-catalyst filter effectively eliminates odor and

cigarette smoke in the room air.

 Optional Active carbon filter/Electrostatic filter is particularly effective in eliminating

odor and microscopic dust.

Life Time of Filters

 The life of above filters varies according to the amount of cigarette smoke, room size and
the operating time.

 Air filters can be cleaned with a vacuum cleaner or rinsed under running water after
using a month.

 The life time of optional Active carbon filter is about 2 years and that of optional
Electrostatic filter is about 3 months. These filters cannot be recycled.

 The life time of optional Photo-catalyst filter is about 2 years. This filter can be washed
under running water and can be refreshed by exposing under direct sunlight. Exposure
time is 6 hours after using for 3 months.

Note: Additional information for air filter.
Refer to Unit of competency: Service and Maintain Window-Type Air-
Conditioning/Domestic Refrigeration Units.

Job Sheet Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
#2
Module Servicing and Maintaining Package-Type Air-Conditioning Unit/ Page 18

Commercial Refrigeration Equipment

CARE AND MAINTENANCE

Cleaning the Filters and Front Panel

 Turn off the unit and pull out the power plug.
 Clean the air filters once a month.

1. Lift the front panel and pull 3. Clean the filters with a 3. Rinse the filters under
the air filters downwards. vacuum cleaner. running water and dry
them completely, and then
refit them correctly into
their guides.

Refreshing the Optional Photo-catalyst filter

1. Lift the front panel and put 2. Blow off the dust from the 3. Expose under direct
the optional photo-catalyst filter with fresh air or wash sunlight for 6 hours and
filter downward. the filter under running refit correctly into its guide.
water.

Washing the Front Panel
Note:

 Turn off the unit and pull out the power plug.
 Clean the front panel if it becomes dirty and spotted.
 Front panel is removable.

1. Lift the front panel up to 2. Rinse the panel under 3. Refit it correctly.
the top of the unit, then running water and dry it Installation procedure is
separate the front panel completely in a shaded reverse to the removal
from the unit. area. procedure.

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Commercial Refrigeration Equipment

Cleaning the Main Unit

 Use only a damp soapy towel.  Do not pour water onto the unit and do not
use petrol, solvents or abrasive powder
which may result in damage to the unit.

Note:
 When cleaning the unit, first turn it off and pull out the power plug.

After-Season Care
1. Clean the filters and refit them into the unit. 2. If the unit to be switched off for an extended

period, run the unit on FAN only for two
hours to dry inside of the unit.

3. Clean the indoor and outdoor unit and wrap
the outdoor unit with a protection cover.

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INFORMATION SHEET #2

Check and Adjust Air-Conditioning and Refrigeration Components, Controls and
Operating Condition

This material will guide you in performing the following operations:

 obtain the operating data of the equipment;
 check head pressure or suction pressure;
 check the refrigerant charge in the system;
 check the motor for excessive temperature;
 check for leaks in the suction valve and discharge valve;
 check the condition and lubrication of the bearings;
 check the amount of lubrication in the motor and refrigeration system;
 check the shaft seals for leaks;
 check the compressor, condenser and evaporator for excessive low or high temperature;
 check the condenser cooling water temperature flow rate; and
 check the condition of belts and couplings.

The following equipment and instrument will be used for the above operations:

Quantity Unit Description
1 unit Available refrigerating unit
1 unit Gauge set

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Commercial Refrigeration Equipment

INTRODUCTION:

Refrigeration machinery may not require major regular maintenance when small problems are
detected and corrected before they become big problems. The reliability of the system can be
maintained through periodic inspection by a qualified refrigeration man. His services must be
utilized and his recommendation must be acted upon.

Shown below is a typical refrigeration system with a refrigeration man doing visual inspection as
a means of preventive maintenance or doing a maintenance check-up of the system.

SERVICING EQUIPMENT

Some compressors are
equipped with suction
and discharge pressure
gauges which indicate
evaporator and
condensing pressures
respectively. However,
most compressors do
not have permanently
mounted pressure
gauges and in such
cases a particular unit
known as a GAUGE
MANIFOLD is used. The
service manifold is one
of the most versatile
instruments that the field
serviceman has utilized
to determine the
operating conditions of
the refrigeration system.
The manifold is connected to the suction service valve and the discharge service valve with
flexible lines. The actual connection shall be explained in time latter pages.

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Commercial Refrigeration Equipment

The service valves on the other hand, are fitted to the suction amid discharge ports of the
compressor and their construction is discussed in the following section. See illustration on figure
above for the location of service valves.

COMPRESSOR SERVICE VALVES AND FITTINGS

Before gauges and service Nomenclature of service valve assembly
cylinders can be titled to the
system or any part removed
from a system, a knowledge
of the construction and
functioning of the valves is
essential. See figure.
There are three main service
valves:

1. Suction service valves
(SSV)

2. Discharge service valves
(DSV)

3. Liquid receiver service
valves (LRSV)

1. Flare nut 6. Seal cap
2. Union 7. Valve Body
3. Spindle 8. Gauge plug
4. Gland washer 9. Washer packing
5. Gland nut 10. Seal cap washer

The suction and discharge service valves have a front and a back seating arrangement, so that
the gauge manifold may be fitted to the system, while the liquid receiver service valve usually
has one seat.

The various positions of the valve spindle on both the suction and discharge service valves are
as follows:

Back Seated - this is when the spindle is turned
fully backwards closing the gauge
port.

Mid-seated - in this position the spindle can be
turn mid way of the valve allowing
the gauge port line connection
and compressor connection open.

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Front seated - this is when the spindle is turned
fully forward thus closing the line
connection.

SAFETY PROCEDURES IN HANDLING SERVICE VALVE

1. Always slacken off (loosen) gland packing nut before attempting to turn the valve stem.
2. Always use a ratchet spanner or key to suit the size of the valve stem.
3. NEVER FORCE the valve against its seat; this may score it or “freeze” the stem and seat

together.
4. Give the valve stein a drop of refrigeration oil occasionally.
5. Always back seat the service valve spindle before removing the gauge plug.
6. When service work is completed the gauge plug must be replaced, the gland nut tightened

and the sealing cap, complete the sealing washer inserted, replace on the service valve
tightened.

VALVE WRENCH AND SPANNERS

Service valve is the access point to refrigeration system. It serves as a key accessory in
servicing operation. Being one of the most important accessories in refrigeration system, care
should be taken in consideration. To handle the valve carefully, special access tools are being
used. These are:

a. Valve ratchet wrench

This is a special tool used mainly in servicing
operation. It is design for the purpose of
accessing service valve. The wrench suit to
the valve stem and fit it snugly to avoid
slippage that could wear or damage it.
b. Adjustable wrench

This tool is not new to us, this is a universal
tool commonly used by a mechanic. The jaw
of this wrench can be adjusted to fit the size of
nut and/or flare cap. In servicing operation this
used particularly on opening of service valve
cap and service port cap.

THE COMBINATION GAUGE MANIFOLD

The combination gauge manifold is a necessary instrument for the serviceman, enabling him to
check and service refrigeration system. The gauge manifold is usually fitted to the compressor
service valves to obtain high and low side pressure in the system, and may be used for nearly

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all service operations, such as adding or removing refrigerant, purging off air or excess
refrigerant, and by-passing pressure from high to low side of the system.

The combination gauge manifold should be given proper care, the gauges protected from
vibration and the threaded or flared ends should be provided with protective covers, it is
important to prevent entry of moisture and dirt into the hoses and manifold when not in use and
so avoid contaminating the refrigeration system. The gauges themselves should be checked
periodically so that so that accurate readings are taken at all times. A routine check before
using the compound gauge should be to see that the needle reads zero when the gauge is
open to the atmosphere.

CONSTRUCTION OF THE MANIFOLD

Basically the gauge manifold consists of compound amid
high pressure gauges mounted oil a manifold with hand
valves to isolate the common connection, or open it to either
side as desired. The construction of the valves allows full
flow of refrigerant to the gauge at all times.

Gauge manifold set

The two types of gauges are incorporated into the manifold, Flexible hoses
these are: Compound gauge
Pressure gauge
1. Low Pressure Gauge:

The compound gauge indicates pressures above and
also those below atmospheric pressures (vacuum). This
is used to measure the low pressure or evaporator side
of the system and is connected to the suction service
valves.
2. High Pressure Gauge:

This gauge is used on the high pressure or condenser
side of the system and is connected to the discharge
service valves.

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CARE IN HANDLING GAUGE MANIFOLD

1. Always blank-off (cover) the manifold lines when not in use to prevent entrance and
contamination of air.

2. Inspect the rubber of flexible hose before and after using it. If indication of wearing is
detected replace it at once.

3. Wipe-off oil and grease after using the gauge manifold. Remaining oil in it would catch dust
and forms heavy dirt. It is very hard to remove and unsafe to use.

4. Calibrate the gauge regularly before using.

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Commercial Refrigeration Equipment

JOB SHEET #3

DISMANTLING, INSPECTING, AND REASSEMBLING SERVICE VALVES

TOOLS AND MATERIALS

Discharge line valve Ratchet wrench, 1/4 in.
Suction tine valve Graphite packing
Liquid line valve Packing gland
Service valve wrench, 1/4 in. Packing nut wrench
Adjustable end wrench

PROCEDURES

A. Two-way Service Valve
1. Obtain a two-way suction line valve from the instructor.
2. Remove the end cap with an adjustable wrench. Record your observations.
3. Remove the packing gland nut with the packing nut wrench.
4. Remove the valve stem using the 1/4-in, ratchet wrench.
5. Lay out the parts on a flat surface in the order of removal.
6. Proceed to clean all parts with dry rags.
7. Make a list of the parts in the table below and indicate the function of each part.
8. Reassemble the parts in their proper order.

B. One-Way Service Valve
Repeat steps 1 through 8 in port A.

C. Liquid Line Valve
Repeat steps 1 through 8 in part A.

Operating Data

These are the basics used by a refrigeration man in troubleshooting a system.

An example of operating data of a motor is shown below:

1. Motors are identified from the information
in the rating plate. This includes:

- Maker’s name or trade mark.
- Type of supply, e.g., 3-phase, 38-0 V,

50 cycles.
- Rated power, e.g., 5 Hp.
- Rating, e.g., continuous operation.
- Speed, e.g., 1450 rev/mm.
- Serial number of motor.
- Frame reference number.
- Additional information.

Typical Rating Plate

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Check Head or Suction Pressures

2. Install the gauge manifold set, as shown.

NOTE:

Refer to L.E. “Gauge and Manifold Set” if
necessary.

Head Pressure Test

3. Head pressure should not exceed 60 psi.
(4.20 kg/cm2), as shown.

4. If head pressure exceeds 60 psi (4.20
kg/cm2), it is possible that the condenser is
clogged and needs cleaning. Clean the
condenser as shown.

Refer to the L.E. on “Cleaning, Removing
and/or Replacing Condensers” if
necessary.

Check the Refrigerant Charge in the System

5. A popular method to check for refrigerant
charge is to mount a glass sight gauge in
the liquid line, as shown.

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6. Bubbles indicate that there is insufficient
refrigerant.

7. Add refrigerant.
NOTE:

Refer to L.E. “Charging the System with
Refrigerant” if necessary.

8. Checking the Motor for Excessive
Temperature

NOTE:
Do not use your hand to check the
temperature of the motor.

9. Use a thermometer and check the reading
against the allowable temperature shown
on the name plate.

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10. The temperature of the motor should not
rise more than 40ºC (72ºF) over room
temperature.

Checking for Leaks in the Suction Valve and Discharge Valve

To test for leaks on the low pressure side oi a
compressor, such as at the gaskets, at the
suction service valve, or at the crankshaft seal,
one may use one of two methods:

11. Close the suction service valve and draw
as high a vacuum on the compressor as
possible. Then turn the discharge service
valve all the way in.

12. Keep the compressor running. If the head
pressure gradually rises, it means that air
is being drawn into the low side off the
system.

13. A better way is to balance the pressures in
the crankcase and turn the discharge
service valve all the way in, as shown.

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14. Remove the discharge service valve gauge
plug and connect a 250 mm length of
copper line, as shown.

15. Immerse the copper line into a glass bottle
partly filled with oil, as shown.

16. If the tube discharges gas continuously as
shown by air bubbles it means air is being
admitted to the low side of the compressor.

17. If there are no leaks, the bubbling will stop
immediately after the compressor is
started.

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SELF-CHECK #1

CALL YOUR INSTRUCTOR who will observe you perform maintenance check-up.

Instructor’s checklist Acceptability
1. Obtaining operating data of the equipment Yes No
2. Checking the head and suction pressure ______ ______
3. Checking the refrigerant charge in the system ______ ______
4. Checking motor for excessive temperature ______ ______
5. Checking for leaks in the suction valve and discharge valve ______ ______
______ ______

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#2
Commercial Refrigeration Equipment

Learning Outcome # 2 : Maintain Lubrication System in PACU/CRE.

Assessment Criteria:

 Lubrication system variables and components were checked and adjusted to meet
operational specifications

 Oil levels, properties and circulation balances were checked and adjusted to meet
operational specifications

 Oil leaks were detected and rectified to ensure operational efficiency

 Recovered refrigerant in the tank must be labeled prior to recycling

Resources:

 Refrigeration and air conditioning technology book
 Carrier owner’s manual
 Learning Element

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#2
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LEARNING EXPERIENCES

LEARNING OUTCOME NO. 2: Maintain Lubrication System in PACU/CRE.

Learning Activities Resources

1. Read the information sheet “Checking the  Information Sheet #3
Condition and Lubrication of the Bearings”.

2. Answer the Self-Check #2.  Self Check #2

3. Ask instructor if you can proceed to the
next learning outcome.

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INFORMATION SHEET #3

Checking the Condition and Lubrication of the Bearings

1. An increase iii temperature particularly at
the bearing housing section of the
equipment is an indication that the bearing
is excessively starved of lubrication.

This can be checked by feeling with the
hands. A more accurate means of checking
would be to use a thermometer.

2. A damaged bearing is indicated by
excessive noise while the motor is running.
Most often, this is accompanied by an
increase in temperature.

Checking the Shaft Seals for Leaks

3. A noisy seal will soon become a leaky one
if not attended to.

It may be remedied by the usual process of
lapping the seal, or it may sometimes be
repaired by tapping the seal box lightly with
a hammer.

4. A leaky seal may be detected by the usual
test for leaks (ammonia for sulfur dioxide).

.

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SELF-CHECK #2

CALL YOUR INSTRUCTOR who will observe you perform maintenance check-up.

Instructor’s checklist Acceptability
1. Checking for leaks in the suction valve and discharge valve Yes No
2. Checking the condition and lubrication of the bearing ______ ______
3. Checking the shaft seals for leaks
______ ______

______ ______

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Commercial Refrigeration Equipment

Learning Outcome # 3 : Maintain Refrigeration System in PACU/CRE.

Assessment Criteria:

 Pressure drops across strainer, filters, and filter drier are checked and recorded.

 Refrigerant leaks are detected and rectified to secure operational efficiency

 Refrigerant system variables and contaminated are checked and adjusted to meet the
operational efficiency

Resources:

 Refrigeration and air conditioning technology book
 Carrier owner’s manual
 Learning Element

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Outcome
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#3
Commercial Refrigeration Equipment

LEARNING EXPERIENCES

LEARNING OUTCOME NO. 3: Maintain Refrigeration System in PACU/CRE.

Learning Activities Resources
 Information Sheet #4
1. Read the information sheet “Poor  Self Check #1
Condensation in PACU/CRE”.

2. Answer the Self-Check #1.

3. Ask instructor if you can proceed to the
next learning outcome.

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INFORMATION SHEET #4

Poor Condensation in PACU/CRE

To determine what is responsible for a poor condensing condition proceed, as follows.

1. Install a gauge manifold, as shown. Refer
to L.E. on “Gauge and Manifold Set”, if
necessary.

2. Determine head pressure. The head
pressure should be 165-205 psig
1.14 x 10-4 Pa to
1.14 x 10-4 Pa at 100ºF

NOTE:

If the head pressure registered is more
than the range mentioned; then the system
has too much refrigerant, too much oil or
has a corroded interior.

Checking the compressor, condenser and the evaporator for excessive low or high temperature.

3. Compressor

Compressors are checked by using a
thermometer, as shown. Temperature
range should be from 65ºF to 115ºF.

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4. Condensers

Condensers whether air cooled or
water cooled are installed to remove
heat. The condensers will fail to do its
job if the heat transfer surfaces are
inefficient.

Evaporators

5. Install a. thermometer on the
evaporator tube, as shown.

6. A reading of between 5ºF to 15ºF (-
15ºC to -45ºC) should be registered.

NOTE:

If reading does not reach the range, it
means a lack of refrigerant. Add
refrigerant. Refer to L.E. “Charging the
system with Refrigerant”, if necessary.

Checking the Condenser Cooling Water Flow Rate

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7. Too much water flow will give a very
satisfactory refrigeration.

8. Less water flow clue to leaky valves or
water lines gives unsatisfactory
refrigeration.

9. Adjust valve to control the flow rate of
water by turning the valve stem
clockwise or counterclockwise, as
shown.

10. Install the water flow meter or gauge
to determine the flow of water, as
shown.

Checking the Condition of Belts and Coupling

11. Fan belts need periodical checking for
its tension, as shown. Amount of sag
should not exceed 1/2” (12mm), as
shown.

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Commercial Refrigeration Equipment

SELF-CHECK #3

CALL YOUR INSTRUCTOR who will observe you perform maintenance check-up.

Instructor’s checklist Acceptability
Yes No
1. Checking the compressor, condenser and evaporator for ______ ______
excessive low or high temperature
______ ______
2. Checking the condenser cooling water and flow rate
______ ______
3. Checking the condition of belts and couplings

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#4
Commercial Refrigeration Equipment

Learning Outcome # 4 : Maintain Secondary Heat Transfer Equipment in PACU/CRE.

Assessment Criteria:

 Liquid properties are adjusted to meet specified standard
 Follow-up action is arranged in accordance with workplace procedures

Resources:

 Refrigeration and air conditioning technology book
 Carrier owner’s manual
 Learning Element

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Outcome
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#4
Commercial Refrigeration Equipment

LEARNING EXPERIENCES

LEARNING OUTCOME NO. 4: Maintain Secondary Heat Transfer Equipment in PACU/CRE

Learning Activities Resources

1. Read the information sheet “Cooling Tower and Evaporative  Information Sheet #5
Condenser”.

2. Read and perform the procedures in the job sheet “Test the  Job Sheet #4

Efficiency of Compressor” and answer the questions. Write your

answers on a piece of paper and have them checked by your

instructor.

3. Read and perform the procedures in the job sheet “Charge Oil  Job Sheet #5
in the Compressor” and call your instructor to check your work.

4. Read and perform the procedures in the job sheet “Evacuate  Job Sheet #6
the System” and call your instructor to check your work.

5. Read and perform the procedures in the job sheet “Charge  Job Sheet #7
Refrigerant in the System” and call your instructor to check your

work.

6. Read and perform the procedures in the job sheet “Test Leaks  Job Sheet #8
in the System” and call your instructor to check your work using

the listed evaluation criteria.

7. Read and perform the procedures in the job sheet “Remove and  Job Sheet #9
Replace Filter Drier” and call your instructor to check your work

using the listed evaluation criteria.

8. Read and perform the procedures in the job sheet “Remove and  Job Sheet #10
Replace Oil Separator” and answer the questions. Write your

answers on a piece of paper and have them checked by your

instructor.

9. Read and perform the procedures in the job sheet “Remove and  Job Sheet #11
Replace or Clean Thermostatic Expansion Valve Strainer” and.

and call your instructor to check your work using the listed

evaluation criteria

10. Read and perform the procedures in the job sheet “Service  Job Sheet #12
Commercial Refrigerating System” and answer the questions.

Write your answers on a piece of paper and have them checked

by your instructor.

11. Ask instructor if you can proceed to the next learning outcome.

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INFORMATION SHEET #5

Maintain Secondary Heat Transfer Equipment

COOLING TOWER AND EVAPORATIVE CONDENSER

Heat from water cooled may be transferred to the surrounding through a cooling tower or an
evaporative condenser.

1. A cooling tower contains apparatus which sprays the condenser water through a blast of air
(some design rely on the wind created by spraying itself; others use fans). Some of the
water evaporates and loses the latent heat of vaporization. The remaining water dries to the
bottom and is returned to the condenser foil reuse. Chemicals may be needed to control
rust, algae fungus and the organism that causes legionnaires disease, which grows inside
the cooling tower. During operation, a cooling tower receives enough condenser heat to
keep it from freezing. The system must be able to empty itself of water when not in use to
prevent freezing.

2. An evaporative condenser also uses evaporation to remove heat. In this device, the
condenser water flows through a heat exchanger which is under a spray or drip of water.
Fan blow air across the condenser during operation. Build up of scale is visible in this
device.

Shell and Tube or Coil

In a shell and tube condenser is a large cylinder with a water manifold at each end. Water
recirculates through the large cylinder. Hot refrigerant vapor enters the inlet manifold and flows
through the cooling tubes and exits the discharge manifold.

A shell and coil is also a cylinder with two manifolds but the refrigerant flows through coiled
tubes instead of straight ones. Due to their shape, the coil must be cleaned with chemicals not
brushes.

Tube-Within-a-Tube

In this model, the outer tube contains refrigerant and the inner tube contains water. The two
fluids flow in opposite direction to the incoming cold water contacts the refrigerant that is just
about to flow to the receiver. This ensures the greatest temperature reduction in the refrigerant.
The wall between the two fluids may be shaped to increase its area and the rate of heat
transfer. The tube-within-a-tube type has too little space to store refrigerant and cannot serve as
a liquid receiver. Consequently, the tube-within-a-tube type is easy to overcharge which
reduces the space available for heat transfer and can cause erratic cooling.

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WATER TREATMENT

All air-conditioning systems using water-cooled condensers require some form of water
treatment. This treatment is necessary because water (from any source such as wells, lakes,
and rivers) contains impurities in the form of minerals, gases, organic matter, algae, and
bacterial slime. These impurities act on the condenser water system in the following ways:

 Minerals cause the formation of scale on the metal surfaces.
 Guns In the atmosphere, such as carbon dioxide and sulfur dioxide, form acids when

they come into contact with the water. These acids eventually attack and corrode the
metal surfaces.

 Algae attach themselves to the surfaces of the system. Since algae are living plants, they
grow until the passages of the system are closed. Bacteria form slime and clog the
system in much the same way as algae.

Most of the Impurities found in water can be neutralized by chemicals which are prepared to
perform a specific function. For example, specific chemical compounds can suspend minerals,
dissolve scale, neutralize acids, coat the surface of the metal with a protective film, or attack
and kill algae and bacteria.

Some of the chemical compounds used to remove scale or neutralize acids can be harmful
to wood and to certain metallic and composition materials used in valves, valve diaphragms,
and cooling tower fill. Care must be exercised when these chemical compounds are used in
condensers and cooling towers. It is recommended that a water treatment specialist be
consulted for each system requiring some form of water treatment.

HARD AND SOFT WATER

Water is classified as hard or soft depending upon the amount of solid impurities contained
In the water. In general, water containing less than 200 parts per million (ppm) of mold material
is considered to be soft water. Hard water contains solids in amounts greater than 200 parts per
million (ppm). In terms of grains of hardness, 100 ppm to 200 ppm is roughly equivalent to 6 to
11 grains of hardness per gallon of water; 200 ppm to 300 ppm is equivalent to 12 to 17 grains
of hardness pergallon of water; and 300 ppm to 400 ppm is equivalent to 18 to 24 grains of
hardness per gallon of water.

CONTROLLING SCALE

Scale formation is controlled by compounds called scale inhibitors. Some minerals tend to
accumulate and become more concentrated as the water in the system evaporates. An inhibitor
holds these mineral solids in suspension in the water. If the inhibitor is used in the water and a
water bleedoff is provided in the system, the suspended solids flow from the system through the
bleed pipe. Thus, the solids do not accumulate and the concentration of solids is maintained at
a minimum level. The amount of bleedoff can vary from four gallons per hour for five-ton tmits to
360 gallons per hour far 100-ton units. For each unit size, the bleedoff also varies according to
the hardness of the water.

Based on the specifications determined by a water treatment specialist, one water scale
treatment can maintain the amount of solids in the water at a safe level for three months or
more.

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Removing scale through the condenser only.

REMOVING SCALE

To remove accumulated scale from a system, the services of a water treatment specialist
should be obtained. The specialist can determine the type of scale present. A suitable chemical
compound and the quantity of this compound necessary to remove the scale can then be
recommended. In most cases, the chemical should not be allowed to pass through the cooling
tower.

Unless otherwise specified by the water
treatment specialist, the chemical should pass
through the condenser only, figure 1. This
precaution is recommended because most
scale removers are acid compounds that can
damage the materials in the cooling tower.
(However, the acid may be mild enough that
the water treatment specialist considers it to
be harmless to the materials in the cooling
tower.)

If the scale removing solution is harmless
to the materials in the cooling tower, the
solution can be added to the system at the
points shown in figure 2 for a forced-draft
tower. Part A in the figure is the tower
distributor plate. Part B is the tower sump, and
Part C is the water tank. For natural-draft
tower, figure 3, the solution is added at the
sump (Part B).

Figure 2. Forced-draft tower.

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It is a good practice to clean the sump
before the scale remover is added. This action
is recommended because the sludge in the
sump Is likely to absorb some of the cleaning
strength of the remover.

CORROSION

Corrosion in a system can occur in the
following ways:

 Acids are caused by gases from the
atmosphere dissolving in the water.
These acids gradually increase in
strength until they begin to attack and
etch the metal surfaces in the system.

Figure 3. Natural-draft tower

 One of the metals used in the system is dissolved by the action of electrolysis resulting
from the connection of two unlike metals. The two dissimilar metals set up an electric
current with the result that one metal dissolves and goes into solution. Some
combinations of dissimilar metals react faster than other combinations.

 Oxygen enters the water from the atmosphere resulting in pitting of the metal surfaces in
the system.

CORROSION CONTROL

Corrosion can be controlled in the water system by the addition of chemically blended
polyphosphates or other similar compounds. The polyphosphate compound deposits a film over
the entire surface of the metal. This compound also protects the metal surfaces from some of
the milk acids that form from atmospheric gases.

Electrolysis can be prevented by following a few general rules.

 If dissimilar metals are joined in the system, the metals should be electrically insulated
from each other.

 If copper and steel are used in the system piping, large surfaces of copper and small
surfaces of steel result in rapid corrosion of the steel. Small areas of copper and large
areas of steel cause the steel to corrode, but at a rate which is much slower titan for the
previous case. A similar corrosive action will result when brass and steel are combined.

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CONTROLLING ALGAE AND SLIME

Algae and slime are controlled by the use of toxic compounds commonly called algaecides.
Chlorine is an algaecide. Since one type of algae vows best in daylight and mater flourishes in
darkness, one type of algaecide may be suitable and effective for indoor cooling tower
installations. Another type of algaecide may be more effective hr outdoor installations where the
tower ii exposed to daylight. In all instance, a water treatment specialist should be consulted to
determine the algaecide that is likely to produce the best results. Algae treatment usually lasts
one month or more depending upon the conditions of the water and the atmosphere around the
tower.

All algaecide compounds are toxic; therefore, the skin and eyes should be protected when
these compounds are handled.

The most important rule to be followed regarding water treatment or water treatment
problems is to obtain the services of a reputable water treatment specialist.

SUMMARY

 Cooling towers are designed to operate on the principle of -
1. natural draft where natural air currents cool the circulated water; or,
2. forced draft in which a fan blows or draws air through the tower to cool the circulated
water.

 In forced-draft towers, the discharge air should blow in the same direction as the
prevailing wind.

 To install a forced-draft tower:
1. Locate the tower
2. Prepare a foundation
3. Install the Ian motor and belts
4. Install the water piping and pump
5. Connect the fan motor and water pump wiring

 To install a natural-draft tower:
1. Locate the tower
2. Prepare a foundation
3. Install the water piping and pump

 Water treatment is required in systems using water-cooled condensers because:

1. Minerals in the water cause scale formation on metal surfaces.
2. Atmospheric gases form acids in the water; these acids corrode the metal surfaces.
3. Algae and bacteria clog the system passages.

 Hard water contains relatively large amounts of solid impurities; soft water has relatively
small amounts of impurities.

 Scale formation is controlled by inhibitors. Some systems are designed so that the solids
suspended by the inhibitor can be removed.