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EPA 608 NEC 2023

EPA 608 Type II & III Practice Test 6

This test focuses on purge units, a device unique to Type III low-pressure chillers. It covers how purge units remove non-condensable gases like air and moisture while returning refrigerant vapor to the system.

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The EPA 608 certification is required by law for any technician who purchases or handles refrigerants. It covers safe handling, leak detection, recovery, and environmental regulations.

Type I covers small appliances (≤5 lbs refrigerant), Type II covers high-pressure systems, Type III covers low-pressure systems, and Universal covers all three. Most HVAC technicians pursue Universal certification.

You must score at least 70% on each section of the exam. The Universal exam has four parts: core, Type I, Type II, and Type III.

Type II & III Exam Tip: Purge units are unique to Type III chillers. Rising purge activity often signals a leak that is letting outside air into the system.

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25 min

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EPA 608 Type II & III Practice Test 6 — Question List

Question 1: What is a purge unit's main job on a low-pressure chiller?

Continuously remove non-condensable gases like air and moisture while returning refrigerant vapor to the system
Add refrigerant automatically
Heat the system for leak testing
Recover the full refrigerant charge

Question 2: Purge units are found on which type of equipment?

Type II rooftop units
Residential split systems
Walk-in coolers
Low-pressure Type III chillers

Question 3: Why do low-pressure chillers need a purge unit but typical Type II systems do not?

Type II systems never have air enter them
Because Type III chillers run below atmospheric pressure, leaks pull air and moisture in over time, which must be continuously removed
Purge units are just for looks
Type II systems are too small to need one

Question 4: What does a purge unit do with refrigerant vapor that gets mixed in with the non-condensable gases?

It vents it to the atmosphere
It stores it in a separate tank permanently
It converts it into oil
It returns the refrigerant vapor back to the system

Question 5: A purge unit on a hospital chiller is found to be venting refrigerant vapor along with the non-condensable gases instead of returning it. What does this suggest?

The purge unit is working perfectly
This is normal and expected
The purge unit may not be separating gases correctly and could be violating the venting ban by releasing refrigerant
The chiller has too little refrigerant

Question 6: True or False: A purge unit runs continuously to remove non-condensable gases from a low-pressure chiller.

False
True
True, but only once a year
False, purge units only run during repairs

Question 7: Which of the following systems does NOT typically have a purge unit?

Large centrifugal chiller
Low-pressure chiller cooling a university
Rooftop package unit
Any Type III low-pressure system

Question 8: A technician notices the purge unit on a chiller is discharging more air than usual this month. What should the technician suspect and check for?

Too much refrigerant in the system
A broken thermostat
A refrigerant leak letting more air into the system
An oversized compressor

Question 9: Why is it important that a purge unit be checked and maintained regularly on a low-pressure chiller?

So it continues to properly remove non-condensable gases and return refrigerant vapor, keeping the system efficient and preventing refrigerant loss
So it can vent refrigerant more easily
It has no real importance
So it can add more refrigerant automatically

Question 10: What kind of gases does a purge unit remove?

Refrigerant only
Non-condensable gases, such as air and moisture
Oil vapor only
Only nitrogen

Question 11: True or False: A purge unit is required equipment on typical Type II rooftop units.

True
True, only in cold climates
False
True, only on units over 5 tons

Question 12: What non-refrigerant substance commonly enters a low-pressure chiller along with air through a leak?

Moisture, or water vapor
Oil
Dust only
Nitrogen

Question 13: A technician is troubleshooting reduced chiller efficiency. The purge unit log shows a steady increase in purge activity over several months, with no maintenance performed. What should the technician do first?

Ignore the log, since purge activity does not matter
Immediately replace the entire chiller
Add more refrigerant to compensate
Investigate for a leak that may be letting increasing amounts of air into the system

Question 14: Is there a Type II equivalent to a chiller's purge unit?

Yes, all Type II systems have one
Yes, but only on walk-in coolers
Yes, but only on heat pumps
No, purge units are unique to low-pressure chillers

Question 15: True or False: A purge unit vents 100% of what it collects to the outside atmosphere.

False
True
True, but only refrigerant
True, but only air

Question 16: Which best describes the role of a purge unit within the broader topic of chiller maintenance?

It replaces the need for leak testing entirely
It replaces the compressor
It manages ongoing air and moisture intrusion that is a natural result of running below atmospheric pressure
It is only used once, at installation

Question 17: A chiller technician wants to reduce how often the purge unit needs to run. What long-term fix addresses the root cause, rather than just managing the symptom?

Turning off the purge unit
Finding and repairing the leak that is letting air into the system
Adding more refrigerant
Increasing the hot water temperature permanently

Question 18: Why does moisture entering a chiller through a leak matter?

It can cause internal problems if not removed
It always improves efficiency
It has no effect at all
It replaces the need for refrigerant

Question 19: True or False: The venting ban that prohibits releasing refrigerant to the atmosphere still applies to chillers with purge units.

False
True, unless the chiller is over 500 tons
True
False, purge units are exempt

Question 20: Which statement about purge units is TRUE?

They add refrigerant to the system as needed
They are used to leak test the system with hot water
They replace the recovery machine
They remove non-condensable gases and return refrigerant vapor to the system

Question 21: A technician who normally services Type II rooftop units is asked to explain purge units during a training session. How should they describe the concept to trainees used to Type II equipment?

Say Type II units have the same thing under a different name
Explain that purge units are a Type III-specific device, needed because low-pressure chillers pull in air through leaks, unlike Type II systems
Say purge units are optional safety add-ons for Type II units
Say purge units recover the full refrigerant charge instead of the recovery machine

Question 22: What happens to air and moisture that a purge unit removes from a chiller?

They are returned to the system with the refrigerant
They are separated out and released, while refrigerant vapor is kept in the system
They are stored forever inside the chiller
They turn into refrigerant

Question 23: A building owner asks why their chiller has a device, the purge unit, that their old rooftop AC unit never had. What is the best explanation?

The chiller runs below atmospheric pressure and can draw in air through leaks, so it needs a purge unit to remove that air; the rooftop unit runs above atmospheric pressure and does not have this issue
The chiller is simply a newer model
Purge units are just optional accessories
Rooftop units are too small to need one

Question 24: True or False: Increased purge unit activity can be an early warning sign of a developing leak on a low-pressure chiller.

True
False
True, but only in winter
False, purge activity is unrelated to leaks

Question 25: Which statement best summarizes what makes a purge unit necessary on a low-pressure chiller?

It is required by all refrigeration equipment, Type II included
It replaces the need for recovery equipment
It only runs during a hot water leak test
The chiller's below-atmospheric operating pressure allows air and moisture to leak in, so the purge unit continuously removes these non-condensable gases while returning refrigerant vapor to the system

Study Tip: The EPA 608 exam is closed book. Memorize: recovery is required before opening any refrigerant system. Venting refrigerant is illegal. Know the ODP and GWP values for R-22, R-410A, R-134a, R-32, and R-454B.

EXAM CARD EPA 608

Questions25

Time limit25 min

Pass score70%

RegulationEPA Section 608

DifficultyIntermediate

Last reviewedJun 2026

Timer starts immediately. Progress is auto-saved.

Source: EPA Section 608 (40 CFR Part 82)