Refrigerating Engineers & Technicians Association
CIRO STUDY GUIDE
Table of Contents
Introduction to the CIRO Study Guide 2
Calculators 2
CIRO Content Outline 2
Refrigeration System Screens 3
Sample CIRO Screen and Questions 4
Electrical Diagram and Questions 6
The following items will be available on-screen during the test in CIRO
References
Using RETA References On-Screen 7
Formulas 9
Theoretical Discharge Chart – PSIG Scale 10
Theoretical Discharge Chart – PSIA Scale 11
Figures 3 and 4 12
Figures 5 and 7-14 13
Figure 17 14
Figure 18 Electrical Diagram 15
Figure 7-5 Electrical Diagram 16
Ammonia Safety Data Sheet (SDS) 17
CIRO Troubleshooting System Screens 1-24 31
Ammonia Saturated Properties Table 53
© 2021 REFRIGERATING ENGINEERS & TECHNICIANS ASSOCIATION (RETA)
January 2023 CIRO Study Guide Page 1
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
, Introduction to the CIRO Study Guide
This CIRO Study Guide is designed to help you prepare to demonstrate what you
know and can do in this RETA certification test. You will be tested on concepts
addressed in IR-1, IR-2, IR-4, BE-1 and BE-2.
You will improve your chances of earning your CIRO credential by treating this
CIRO Study Guide as you would the technical manuals in a refrigeration facility
where you work. Your chances of earning the CIRO credential improve if you are
familiar with the details in the CIRO Study Guide. Just as your job requires that
you know what is in operating manuals and when to refer to them to understand or
resolve a problem, the CIRO test requires that you know what is in the References
document and when to use it. You will not be told when to use the references for
this test.
Calculators
All calculations for the CIRO examination can be completed with a simple
calculator. Candidates should bring a simple, non-printing calculator. Test centers
are not required to provide a calculator to candidates during this test.
CIRO Content Outline
Content Areas Number of Questions
1. Safety Standards and Practices 20
2. Electricity 15
3. Heat Flow 15
4. Monitoring System Performance 20
5. Valves, Controls and DX Systems 20
6. Liquid Overfeed and Flooded Systems 20
7. Two-Stage and Secondary Coolant Systems 15
8. Evaporator Defrost 10
Total Questions 135
The test includes 10 questions that are distributed across all content areas that are
not included in candidate scores. Test results are based on 125 scored questions.
The 10 pilot questions are being tested for use in future CIRO examinations.
January 2023 CIRO Study Guide Page 2
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
,Refrigeration System Screens
The screens that appear in the CIRO examination provide information about
operating conditions in a refrigeration system. Some screens include information
about both “NORMAL” and “ABNORMAL” operating conditions. The screens
do not specify how much time has passed between these two sets of data. Several
months may have passed between the time when the “NORMAL” and
“ABNORMAL” readings were recorded.
The CIRO examination requires you to demonstrate that you can use these screens
to:
• Determine the condition of the refrigerant at any place in the system by
knowing how to use the information provided.
• Analyze the findings of the conditions and apply your knowledge to adjust
system components to resolve a problem and/or achieve a better running
condition.
• Determine the cost of operating under the conditions indicated in the
screens. In both dollars per hour and in power demand or consumption over
time.
• Use refrigerant properties tables in the CIRO References and in this CIRO
Study Guide to interpret information and/or solve a problem in the system’s
operating conditions. CIRO references in this Study Guide will be available
on screen during the examination.
A sample screen appears on the next page. This is followed by a series of
questions you should consider as you prepare to take the CIRO Examination.
Other sections of this CIRO Study Guide provide similar guidance for this
examination. These include a list of formulas, an Ammonia SDS, Theoretical
Discharge Charts, and refrigerant properties tables. The CIRO Study Guide also
includes 24 screens that provide information that may be needed to answer
questions on the CIRO exam.
January 2023 CIRO Study Guide Page 3
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
, SAMPLE CIRO SCREEN 300 HP SCREW COMPRESSOR –
NH3 NORMAL CONDITIONS
SUCTION PRESSURE 32 PSIG SCREW COMPRESSOR MOTOR 295 AMPS
AMPS
DISCHARGE PRESSURE 154 PSIG SCREW COMPRESSOR MOTOR 480 VAC
VOLTAGE
OIL PRESSURE 55 PSID SCREW COMPRESSOR SLIDE 100%
VALVE POSITION
SUCTION TEMP 26°F CONDENSER WATER SUMP 75°F
TEMP
DISCHARGE TEMP 171°F CONDENSED LIQUID TEMP 85°F
OIL TEMPERATURE 136°F CONDENSER OUTLET PRESSURE151 PSIG
OIL COOLER – OIL INLET 171°F
TEMP
OIL COOLER – 85°F
REFRIGERANT OUTLET - THERMO SIPHON OIL COOLING
TEMP - CONDENSER OUTLET NOT SUBCOOLED
NOTES: POWER FACTOR IS 0.86 MOTOR TYPE IS 3 PHASE
MOTOR EFFICIENCY IS 93%
CONDENSER TYPE IS EVAPORATIVE
SAMPLE CIRO SCREEN 300 HP SCREW COMPRESSOR –
NH3 ABNORMAL CONDITIONS
SUCTION PRESSURE 32 PSIG SCREW COMPRESSOR MOTOR 339 AMPS
AMPS
DISCHARGE PRESSURE 184 PSIG SCREW COMPRESSOR MOTOR 480 VAC
VOLTAGE
OIL PRESSURE 55 PSID SCREW COMPRESSOR SLIDE 100%
VALVE POSITION
SUCTION TEMP 26°F CONDENSER WATER SUMP 75°F
TEMP
DISCHARGE TEMP 192°F CONDENSED LIQUID TEMP 95°F
OIL TEMPERATURE 154°F CONDENSER OUTLET PRESSURE181 PSIG
OIL COOLER – OIL INLET 192°F
TEMP
OIL COOLER – 95°F
REFRIGERANT OUTLET - THERMO SIPHON OIL COOLING
TEMP - CONDENSER OUTLET NOT SUBCOOLED
NOTES: POWER FACTOR IS 0.86 MOTOR TYPE IS 3 PHASE
MOTOR EFFICIENCY IS 93%
CONDENSER TYPE IS EVAPORATIVE
January 2023 CIRO Study Guide Page 4
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
CIRO STUDY GUIDE
Table of Contents
Introduction to the CIRO Study Guide 2
Calculators 2
CIRO Content Outline 2
Refrigeration System Screens 3
Sample CIRO Screen and Questions 4
Electrical Diagram and Questions 6
The following items will be available on-screen during the test in CIRO
References
Using RETA References On-Screen 7
Formulas 9
Theoretical Discharge Chart – PSIG Scale 10
Theoretical Discharge Chart – PSIA Scale 11
Figures 3 and 4 12
Figures 5 and 7-14 13
Figure 17 14
Figure 18 Electrical Diagram 15
Figure 7-5 Electrical Diagram 16
Ammonia Safety Data Sheet (SDS) 17
CIRO Troubleshooting System Screens 1-24 31
Ammonia Saturated Properties Table 53
© 2021 REFRIGERATING ENGINEERS & TECHNICIANS ASSOCIATION (RETA)
January 2023 CIRO Study Guide Page 1
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
, Introduction to the CIRO Study Guide
This CIRO Study Guide is designed to help you prepare to demonstrate what you
know and can do in this RETA certification test. You will be tested on concepts
addressed in IR-1, IR-2, IR-4, BE-1 and BE-2.
You will improve your chances of earning your CIRO credential by treating this
CIRO Study Guide as you would the technical manuals in a refrigeration facility
where you work. Your chances of earning the CIRO credential improve if you are
familiar with the details in the CIRO Study Guide. Just as your job requires that
you know what is in operating manuals and when to refer to them to understand or
resolve a problem, the CIRO test requires that you know what is in the References
document and when to use it. You will not be told when to use the references for
this test.
Calculators
All calculations for the CIRO examination can be completed with a simple
calculator. Candidates should bring a simple, non-printing calculator. Test centers
are not required to provide a calculator to candidates during this test.
CIRO Content Outline
Content Areas Number of Questions
1. Safety Standards and Practices 20
2. Electricity 15
3. Heat Flow 15
4. Monitoring System Performance 20
5. Valves, Controls and DX Systems 20
6. Liquid Overfeed and Flooded Systems 20
7. Two-Stage and Secondary Coolant Systems 15
8. Evaporator Defrost 10
Total Questions 135
The test includes 10 questions that are distributed across all content areas that are
not included in candidate scores. Test results are based on 125 scored questions.
The 10 pilot questions are being tested for use in future CIRO examinations.
January 2023 CIRO Study Guide Page 2
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
,Refrigeration System Screens
The screens that appear in the CIRO examination provide information about
operating conditions in a refrigeration system. Some screens include information
about both “NORMAL” and “ABNORMAL” operating conditions. The screens
do not specify how much time has passed between these two sets of data. Several
months may have passed between the time when the “NORMAL” and
“ABNORMAL” readings were recorded.
The CIRO examination requires you to demonstrate that you can use these screens
to:
• Determine the condition of the refrigerant at any place in the system by
knowing how to use the information provided.
• Analyze the findings of the conditions and apply your knowledge to adjust
system components to resolve a problem and/or achieve a better running
condition.
• Determine the cost of operating under the conditions indicated in the
screens. In both dollars per hour and in power demand or consumption over
time.
• Use refrigerant properties tables in the CIRO References and in this CIRO
Study Guide to interpret information and/or solve a problem in the system’s
operating conditions. CIRO references in this Study Guide will be available
on screen during the examination.
A sample screen appears on the next page. This is followed by a series of
questions you should consider as you prepare to take the CIRO Examination.
Other sections of this CIRO Study Guide provide similar guidance for this
examination. These include a list of formulas, an Ammonia SDS, Theoretical
Discharge Charts, and refrigerant properties tables. The CIRO Study Guide also
includes 24 screens that provide information that may be needed to answer
questions on the CIRO exam.
January 2023 CIRO Study Guide Page 3
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
, SAMPLE CIRO SCREEN 300 HP SCREW COMPRESSOR –
NH3 NORMAL CONDITIONS
SUCTION PRESSURE 32 PSIG SCREW COMPRESSOR MOTOR 295 AMPS
AMPS
DISCHARGE PRESSURE 154 PSIG SCREW COMPRESSOR MOTOR 480 VAC
VOLTAGE
OIL PRESSURE 55 PSID SCREW COMPRESSOR SLIDE 100%
VALVE POSITION
SUCTION TEMP 26°F CONDENSER WATER SUMP 75°F
TEMP
DISCHARGE TEMP 171°F CONDENSED LIQUID TEMP 85°F
OIL TEMPERATURE 136°F CONDENSER OUTLET PRESSURE151 PSIG
OIL COOLER – OIL INLET 171°F
TEMP
OIL COOLER – 85°F
REFRIGERANT OUTLET - THERMO SIPHON OIL COOLING
TEMP - CONDENSER OUTLET NOT SUBCOOLED
NOTES: POWER FACTOR IS 0.86 MOTOR TYPE IS 3 PHASE
MOTOR EFFICIENCY IS 93%
CONDENSER TYPE IS EVAPORATIVE
SAMPLE CIRO SCREEN 300 HP SCREW COMPRESSOR –
NH3 ABNORMAL CONDITIONS
SUCTION PRESSURE 32 PSIG SCREW COMPRESSOR MOTOR 339 AMPS
AMPS
DISCHARGE PRESSURE 184 PSIG SCREW COMPRESSOR MOTOR 480 VAC
VOLTAGE
OIL PRESSURE 55 PSID SCREW COMPRESSOR SLIDE 100%
VALVE POSITION
SUCTION TEMP 26°F CONDENSER WATER SUMP 75°F
TEMP
DISCHARGE TEMP 192°F CONDENSED LIQUID TEMP 95°F
OIL TEMPERATURE 154°F CONDENSER OUTLET PRESSURE181 PSIG
OIL COOLER – OIL INLET 192°F
TEMP
OIL COOLER – 95°F
REFRIGERANT OUTLET - THERMO SIPHON OIL COOLING
TEMP - CONDENSER OUTLET NOT SUBCOOLED
NOTES: POWER FACTOR IS 0.86 MOTOR TYPE IS 3 PHASE
MOTOR EFFICIENCY IS 93%
CONDENSER TYPE IS EVAPORATIVE
January 2023 CIRO Study Guide Page 4
Revision: 3 Developed: 04/21/2014
Last Reviewed: 12/22/2022 Last Approved: 01/01/2023
Approved by: Harry Wilkins
