11.10 - Master Safety Checklist

Module: Standalone Reference Appendices and Instructor Resources
Purpose: One consolidated pre-service, service, emergency, machinery-room, cylinder, pressure-test, electrical, and flammable-refrigerant safety checklist for EPA Section 608 study and supervised HVAC/R laboratory or field preparation
Safety verification date: August 14, 2026
Primary basis: Current EPA Section 608 Test Topics; current OSHA PPE, respiratory-protection, confined-space, and hazardous-energy-control requirements; current DOT/PHMSA cylinder-transportation requirements; current refrigerant/manufacturer safety information and the safety content already taught in Modules 5, 6, 8, and 9
Important limitation: This checklist supports EPA 608 preparation and safety review. It does not replace the current SDS, equipment manufacturer instructions, employer safety program, applicable ASHRAE/UL/code requirements, OSHA requirements, DOT hazardous-material requirements, or site-specific emergency procedures.

How to Use This Checklist

Use this file:

• Before connecting gauges, hoses, recovery equipment, or cylinders.
• Before leak testing or applying nitrogen.
• Before recovery, evacuation, charging, or opening a refrigerant circuit.
• Before entering or working in a machinery room, pit, vault, or other potentially hazardous space.
• Before hot work.
• Before handling or transporting refrigerant cylinders.
• Before servicing equipment containing A2L, A2, A3, B-class, high-pressure, or unfamiliar refrigerants.
• During EPA 608 examination review.

The course safety sequence is:

RECOGNIZE THE HAZARD
→ REMOVE / AVOID EXPOSURE
→ CONTROL THE SOURCE OR AREA
→ VERIFY SAFE CONDITIONS
→ PERFORM THE WORK

If conditions become uncertain:

STOP
→ DO NOT GUESS
→ CHECK SDS / MANUFACTURER / SITE PROCEDURE
→ VERIFY BEFORE CONTINUING

1. Master Pre-Service Safety Checklist

Before beginning refrigerant work:

• Identify the appliance.
• Identify the refrigerant designation.
• Verify the refrigerant pressure category where relevant.
• Verify the refrigerant ASHRAE safety class where relevant.
• Read the current Safety Data Sheet (SDS) for the refrigerant.
• Review the equipment manufacturer’s service instructions.
• Identify whether the refrigerant is A1, A2L, A2, A3, or B-class where relevant.
• Identify whether the work can release liquid or vapor refrigerant.
• Identify electrical, mechanical, pressure, hot-surface, and stored-energy hazards.
• Verify required PPE.
• Verify adequate ventilation.
• Identify possible ignition sources.
• Verify recovery equipment is suitable for the refrigerant.
• Verify hoses, gauges, fittings, vacuum equipment, and cylinders have adequate pressure ratings.
• Verify tools are approved/suitable for flammable refrigerant if applicable.
• Verify recovery-cylinder condition and available capacity.
• Place the recovery cylinder on a scale when monitoring fill.
• Identify emergency exits and site emergency procedures.
• Confirm machinery-room alarms/monitors are not indicating an unsafe condition.
• Apply required electrical and hazardous-energy controls before opening equipment.
• Do not start work if refrigerant identity, safety class, pressure, equipment condition, or atmospheric safety is uncertain.

First Decision Rule

UNKNOWN REFRIGERANT
or
UNKNOWN ATMOSPHERE
or
UNKNOWN ENERGY STATE
→ DO NOT PROCEED AS IF CONDITIONS ARE NORMAL

2. Personal Protective Equipment Checklist

EPA Section 608 test topics specifically include:

• Gloves.
• Goggles.
• SCBA in extreme cases.
• Refrigerant exposure hazards.

PPE must be selected for the actual task and refrigerant.

2.1 Eye and Face Protection

• Use appropriate primary eye protection when refrigerant splash or vapor exposure can injure the eyes.
• Use chemical-splash goggles or other compliant eye protection appropriate to the hazard.
• Add a face shield when the task requires additional face protection.
• Do not treat an ordinary face shield as an automatic replacement for required primary eye protection.
• Do not assume ordinary prescription glasses provide adequate refrigerant-splash protection.
• Inspect lenses, seals, straps, and shields before use.
• Keep eye protection on during hose connection/disconnection, recovery-cylinder handling, charging, and pressure release.

Memory Rule

FACE SHIELD
→ ADDITIONAL FACE PROTECTION

PRIMARY EYE PROTECTION
→ STILL REQUIRED WHEN THE HAZARD CALLS FOR IT

2.2 Hand and Skin Protection

• Select gloves based on the refrigerant, task, chemical exposure, cold exposure, duration, and SDS/manufacturer guidance.
• Protect exposed skin from liquid refrigerant and rapidly flashing refrigerant.
• Do not assume one glove material is suitable for every refrigerant.
• Replace damaged, saturated, or chemically compromised gloves.
• Keep hands clear of valves/fittings where liquid refrigerant could flash during disconnection.
• Use care around hot compressors, discharge lines, brazing areas, and cylinder surfaces as well as cold refrigerant.

OSHA hand-protection requirements are hazard-based. Refrigerant work can involve:

CHEMICAL HAZARD
+
COLD / THERMAL HAZARD
+
PRESSURE HAZARD

2.3 Clothing and Foot Protection

Where the job requires:

• Wear clothing that reduces exposed skin.
• Avoid loose clothing around rotating machinery.
• Wear work footwear appropriate for cylinder handling, wet floors, machinery rooms, and dropped-object hazards.
• Follow employer/site requirements for flame-resistant or other specialized clothing during hot work or flammable-refrigerant service.

3. Refrigerant Eye and Skin Exposure Checklist

Liquid refrigerant can boil rapidly when released to a lower pressure.

RAPID VAPORIZATION
→ RAPID HEAT REMOVAL
→ COLD BURN / FROSTBITE

3.1 Prevention

• Wear appropriate eye and hand protection.
• Use low-loss fittings where applicable.
• Close valves before disconnecting hoses.
• Keep face and hands away from service-port discharge direction.
• Expect refrigerant to remain trapped in hoses and fittings.
• Do not loosen fittings to “see whether pressure is present.”
• Use approved pressure-reading and recovery procedures instead.

3.2 Non-Frozen Eye Exposure

The course follows the current NIOSH first-aid principle used in Module 6:

• Immediately flush a non-frozen exposed eye with large amounts of water.
• Continue flushing for at least 15 minutes as the course’s general first-response guidance.
• Do not rub the eye.
• Follow the refrigerant SDS and obtain appropriate medical evaluation/guidance.

Product-specific SDS instructions and emergency medical direction control.

3.3 Frozen Skin / Frostbite

For tissue that is actually frozen from refrigerant exposure:

• Stop the exposure.
• Do not rub frozen tissue.
• Do not pull away clothing frozen to the tissue.
• Do not use the ordinary non-frozen chemical-skin-flush procedure as though the tissue were not frozen.
• Obtain prompt medical attention.
• Follow the SDS and emergency procedure.

Exam Memory

REFRIGERANT LIQUID CONTACT
→ FROSTBITE / COLD BURN HAZARD

4. Oxygen Displacement and Asphyxiation Checklist

Many refrigerants can displace air when released in sufficient quantity.

EPA test topics specifically include:

OXYGEN DEPRIVATION

4.1 Before Work

• Evaluate whether a release could accumulate in an enclosed or poorly ventilated area.
• Verify ventilation is operating where required.
• Verify fixed refrigerant/oxygen monitoring systems are functioning where provided.
• Identify pits, trenches, sumps, low areas, equipment enclosures, and other locations where vapor could collect.
• Do not assume every refrigerant has the same vapor density.
• Do not rely on odor as the primary atmospheric-safety method.

4.2 Oxygen-Deficient Atmosphere

Current OSHA general-industry terminology defines:

OXYGEN DEFICIENT
→ less than 19.5% O₂ by volume

Therefore:

19.4% O₂
→ OXYGEN DEFICIENT

• Treat an oxygen-deficiency alarm seriously.
• Evacuate according to the site emergency procedure.
• Do not re-enter merely because ventilation was started.
• Verify atmospheric conditions before authorized re-entry.
• Do not attempt an unplanned rescue in an oxygen-deficient or unknown atmosphere.

5. Confined-Space Checklist

A refrigeration machinery room is not automatically an OSHA confined space.

A separate pit, vault, vessel, water box, or other space may meet the definition.

5.1 Evaluate the Actual Space

Before entry:

• Is the space large enough and configured so an employee can bodily enter?
• Does it have limited or restricted means of entry or exit?
• Is it not designed for continuous employee occupancy?

If all conditions define a confined space, determine whether it is permit-required because it has one or more additional serious hazards.

Examples include:

• Hazardous atmosphere.
• Potential engulfment.
• Internal configuration that could trap/asphyxiate.
• Other recognized serious safety or health hazard.

5.2 Entry Rule

• Follow the employer’s confined-space program.
• Complete required atmospheric testing.
• Follow required permit, attendant, communication, ventilation, rescue, and PPE procedures.
• Do not treat a refrigerant monitor alone as a complete confined-space evaluation.
• Do not enter an unknown atmosphere to investigate an alarm.
• Do not make an impulsive rescue attempt.

Memory Rule

MACHINERY ROOM
≠
AUTOMATIC CONFINED SPACE

but:

PIT / VAULT / WATER BOX / OTHER SPACE
→ MUST BE EVALUATED

6. Respiratory Protection and SCBA Checklist

EPA test topics list:

SCBA
→ IN EXTREME CASES

This does not mean an HVAC technician should simply put on an SCBA and enter a contaminated room.

6.1 General Rule

• Use engineering controls and evacuation where appropriate before relying on respirators.
• Respiratory protection must be selected under the applicable hazard evaluation and respiratory-protection program.
• Required respirator users must meet applicable medical evaluation, fit-testing, training, inspection, and maintenance requirements.
• Air-purifying respirators do not supply oxygen.
• Do not use an air-purifying respirator in an oxygen-deficient atmosphere merely because it has a chemical cartridge.

6.2 IDLH / Oxygen-Deficient Conditions

For an IDLH atmosphere, OSHA requires appropriate atmosphere-supplying respiratory protection meeting the current standard.

The course safety principle is:

UNKNOWN / OXYGEN-DEFICIENT / IDLH ATMOSPHERE
→ DO NOT ENTER WITH ORDINARY HVAC PPE

• Follow the employer’s emergency-response/respiratory-protection program.
• Use only trained, authorized personnel with required respiratory equipment and backup/rescue provisions.
• SCBA is emergency/specialized respiratory protection, not ordinary daily refrigerant-service PPE.

7. Cardiac Effects and High-Concentration Exposure Checklist

EPA Section 608 test topics explicitly include:

CARDIAC EFFECTS

High refrigerant concentrations can create serious systemic effects in addition to oxygen displacement.

The course uses the term:

CARDIAC SENSITIZATION

for the hazard concept associated with some refrigerants/exposures.

7.1 Safety Response

• Avoid inhalation of concentrated refrigerant vapor.
• Leave a contaminated area promptly according to the emergency procedure.
• Move to fresh air only when doing so can be done safely.
• Seek appropriate medical evaluation after significant exposure or symptoms.
• Provide the refrigerant SDS/product information to responders when possible.
• Do not deliberately exercise or exert yourself in a contaminated atmosphere.
• Do not attempt to diagnose the specific exposure by smell.

This course does not direct medication or emergency drug treatment.

Medical treatment belongs to trained medical personnel.

8. Fire, Ignition, and Hot-Surface Checklist

A refrigerant can present fire-related hazards in more than one way.

FLAMMABLE REFRIGERANT + AIR + IGNITION SOURCE
→ FIRE / FLAME PROPAGATION

and:

HALOGENATED REFRIGERANT + HIGH TEMPERATURE
→ THERMAL DECOMPOSITION
→ TOXIC / CORROSIVE PRODUCTS

8.1 Before Hot Work

• Identify the refrigerant.
• Determine whether the refrigerant is flammable or lower-flammability.
• Recover/manage refrigerant according to the approved procedure.
• Do not apply heat to a line intentionally containing refrigerant.
• Verify the area is ventilated as required.
• Remove or control ignition sources where required.
• Follow hot-work permits/site rules where applicable.
• Use only the approved inert-gas/purge procedure.
• Do not use compressed air as a substitute for the approved nitrogen procedure.
• Do not use oxygen for refrigerant-system pressure testing.
• Keep refrigerant cylinders away from brazing/welding heat.
• Verify no trapped pressurized volume will be heated.

8.2 Common Ignition Sources

For flammable refrigerants, control relevant sources such as:

• Open flames.
• Brazing torches.
• Welding.
• Smoking.
• Spark-producing switches.
• Relays/contactors.
• Non-approved motors.
• Hot surfaces.
• Electrical arcs.
• Static discharge where relevant.
• Non-approved leak detectors/tools.
• Grinding/cutting operations.

The actual ignition-control requirements depend on:

• Refrigerant.
• Concentration.
• Equipment design.
• Charge.
• Occupancy.
• Service procedure.
• Applicable code/standard.

9. Toxic and Corrosive Decomposition Products Checklist

High temperature can chemically decompose refrigerants.

The exact products depend on:

• Refrigerant chemistry.
• Temperature.
• Presence of oxygen.
• Flame/hot-surface conditions.

Examples taught in Module 6 include possible formation of:

• Hydrogen fluoride (HF).
• Hydrogen chloride (HCl) where chlorine is present.
• Carbonyl halides under some conditions.

Important Precision

PHOSGENE
≠
UNIVERSAL PRODUCT OF EVERY REFRIGERANT

Some chlorine-containing halocarbon decomposition conditions can produce phosgene/carbonyl-halide hazards, but refrigerants without chlorine cannot simply be assumed to produce phosgene.

9.1 Response

• Stop hot work if an unexpected irritating/pungent atmosphere develops.
• Move away from exposure.
• Follow the SDS/site emergency procedure.
• Ventilate/evaluate the area according to authorized procedure.
• Do not move closer to identify decomposition products by smell.
• Do not assume a refrigerant is safe around flame merely because its normal flammability class is A1/Class 1.

10. Nitrogen Pressure-Testing Checklist

EPA test topics explicitly include:

USE NITROGEN
NOT OXYGEN OR COMPRESSED AIR

and:

PRESSURE REGULATOR
+
RELIEF VALVE
WITH NITROGEN

10.1 Setup

• Use dry nitrogen for the general pressure-test procedure taught in this course.
• Secure the nitrogen cylinder.
• Use a regulator designed for the cylinder/gas.
• Install required downstream relief protection.
• Use hoses/manifold rated for the test pressure.
• Connect according to the approved service procedure.
• Verify which components are exposed to test pressure.
• Determine the manufacturer’s allowable test pressure.
• Protect the lowest-rated component.
• Increase pressure in a controlled manner.
• Monitor the pressure continuously during pressurization.

Conceptual arrangement:

DRY NITROGEN CYLINDER
→ REGULATOR
→ DOWNSTREAM RELIEF PROTECTION
→ MANIFOLD / HOSE
→ APPLIANCE

10.2 Prohibitions

• Do not use oxygen.
• Do not use compressed air.
• Do not exceed manufacturer/component test-pressure limits.
• Do not use an unregulated nitrogen cylinder directly on a refrigerant circuit.
• Do not defeat the relief device.
• Do not use the relief valve as the normal pressure controller.
• Do not perform hot work on a system left pressurized to an unsafe test condition.

Why Not Oxygen / Compressed Air?

Oxygen and compressed air can create:

• Oxidation/fire/explosion hazards.
• Hazardous refrigerant-air mixtures.
• Moisture contamination from compressed air.
• Conditions not intended by the refrigeration system/service procedure.

11. Recovery and Evacuation Safety Checklist

Before recovery:

• Identify refrigerant.
• Select compatible/certified recovery equipment.
• Verify machine inlet and outlet.
• Select approved recovery cylinder.
• Verify cylinder capacity by weight.
• Place cylinder on scale.
• Inspect hoses and low-loss fittings.
• Ventilate the area.
• Control ignition sources for flammable refrigerants.
• Open/close valves in the required sequence.
• Monitor cylinder weight and pressure.

During recovery:

• Do not overfill the cylinder.
• Do not bypass recovery-machine safety cutouts.
• Do not mix known refrigerants in a clean cylinder.
• Do not intentionally vent to speed recovery.
• Stop if pressure, cylinder temperature, refrigerant identity, or equipment behavior becomes abnormal.

Before evacuation:

• Recover refrigerant as required first.
• Confirm the system is ready to be evacuated.
• Use vacuum-rated hoses/fittings.
• Use a micron gauge for deep-vacuum evaluation.
• Protect micron-gauge sensor from refrigerant/oil contamination.
• Do not energize a hermetic compressor under a vacuum condition contrary to the course safety rule/manufacturer instructions.
• Isolate the pump correctly before interpreting a standing-vacuum test.

12. Recovery Cylinder Safety Checklist

12.1 Before Use

• Use an authorized refillable recovery cylinder appropriate for the refrigerant/service.
• Inspect DOT/specification/authorization markings.
• Verify cylinder qualification/requalification status.
• Inspect for rust, corrosion, dents, bulges, gouges, fire/heat damage, and valve damage.
• Identify liquid/vapor ports by labels and cylinder instructions.
• Verify the cylinder contains compatible refrigerant or is appropriately prepared.
• Determine available capacity by weight.
• Place the cylinder on a scale.

12.2 Fill Control

The course exam/training method is:

$$W_{\text{refrigerant,max}}=0.80\cdot WC$$

with:

TW
→ tare / empty weight

WC
→ water capacity

The actual lower manufacturer or transportation limit controls if more restrictive.

• Never intentionally fill a recovery cylinder beyond the applicable limit.
• Do not use cylinder pressure as the primary fill-level indicator.
• Monitor weight during recovery.

EPA test topics specifically warn about:

FILLING RECOVERY CYLINDERS MORE THAN 80% FULL

13. Disposable Cylinder Safety Checklist

• Recognize a disposable refrigerant cylinder as a supply container.
• Never refill it.
• Never use it as a recovery cylinder.
• Do not deliberately vent remaining refrigerant.
• Do not modify the valve.
• Keep it protected from heat and physical damage.
• Follow applicable disposal/recycling instructions after refrigerant is properly removed.

Exam Rule

RECOVERY CYLINDER
→ REFILLABLE

DISPOSABLE CYLINDER
→ NEVER REFILL

14. Cylinder Heat-Exposure Checklist

Heating a sealed cylinder raises internal pressure.

TEMPERATURE ↑
→ SATURATION PRESSURE ↑

If the cylinder is overfilled, liquid thermal expansion also reduces the required vapor space.

14.1 Prevent Excessive Heating

• Keep cylinders away from open flames.
• Keep cylinders away from torches and welding.
• Keep cylinders away from exhaust manifolds/hot engine surfaces.
• Avoid localized heaters.
• Avoid prolonged direct solar heating when practicable.
• Do not use a torch to accelerate refrigerant transfer.
• Follow cylinder and refrigerant manufacturer temperature limits.
• Remove from service any cylinder exposed to fire or serious damaging heat according to current requirements.

Important Current-Rule Precision

Current DOT rules use temperatures around:

55°C / 131°F

in specific cylinder filling/pressure criteria.

That is not a recommended field storage temperature.

Do not convert older generic training numbers such as:

110°F
or
125°F

into a universal current DOT maximum for every refrigerant cylinder.

For field work:

CURRENT CYLINDER REQUIREMENT
+
REFRIGERANT REQUIREMENT
+
MANUFACTURER INSTRUCTION
→ CONTROLS

15. Cylinder Handling and Transportation Checklist

Before transport:

• Verify cylinder is authorized for the material/service.
• Check required markings and hazard labels.
• Close cylinder valves.
• Remove temporary service hoses unless an authorized configuration specifically permits them.
• Install required plugs/caps/valve protection.
• Check for leakage.
• Protect valves from impact.
• Secure cylinders against shifting, rolling, overturning, or ejection.
• Use the employer’s approved vehicle storage/restraint system.
• Keep cylinders away from damaging heat sources.
• Separate incompatible materials where required.
• Verify shipping-paper/label/placard requirements where applicable.
• Do not lift a cylinder by its valve, regulator, or attached hose.

Orientation

The course recommends:

UPRIGHT
+
SECURELY RESTRAINED

as the normal HVAC service-vehicle practice.

Current highway rules can allow other securely restrained orientations in applicable situations; do not confuse preferred service practice with a universal federal upright-only rule.

16. Machinery-Room Safety Checklist

Machinery-room safety can involve:

• Refrigerant detection.
• Oxygen monitoring.
• Alarms.
• Mechanical ventilation.
• Emergency ventilation.
• Pressure relief.
• Electrical/mechanical hazards.
• Confined-space hazards in associated pits/vessels.
• Refrigerant-specific toxicity/flammability.

16.1 Before Entering / Working

• Check alarm status before entering.
• Verify required ventilation is operating.
• Identify refrigerant(s) used in the room.
• Identify refrigerant safety class.
• Know the location of exits.
• Know the location/function of emergency ventilation controls where applicable.
• Know site alarm meaning and response procedure.
• Verify atmosphere if an alarm, release, or suspicious condition exists.
• Do not assume the room is safe because equipment has stopped.
• Remember that refrigerant can continue escaping from piping/vessels after electrical shutdown.
• Do not silence/ignore an alarm merely to continue work.
• Evaluate pits, water boxes, vaults, and associated spaces separately for confined-space hazards.

17. Refrigerant Monitors and Alarms Checklist

A refrigerant detector and an oxygen monitor measure different things.

REFRIGERANT MONITOR
→ TARGET REFRIGERANT CONCENTRATION

OXYGEN MONITOR
→ OXYGEN CONCENTRATION

• Know which instrument is installed.
• Know what its alarm means.
• Do not confuse a refrigerant concentration alarm with an oxygen reading.
• Do not assume one instrument replaces all others.
• Follow current calibration/testing requirements.
• Do not invent a universal detector height or alarm setpoint.
• Use the applicable adopted refrigeration safety standard/code and manufacturer instructions.

EPA examination topics retain machinery-room oxygen-deprivation-sensor wording.

Current field design must follow the applicable current adopted requirements.

18. Ventilation Checklist

Ventilation is an engineering control.

It can:

• Reduce refrigerant concentration.
• Help restore oxygen concentration.
• Remove contaminated air.
• Support machinery-room emergency response.

But:

VENTILATION ON
≠
PROOF OF SAFE ATMOSPHERE

• Use required normal ventilation.
• Activate emergency ventilation according to site procedure.
• Keep exhaust/intake paths unobstructed.
• Do not discharge hazardous exhaust into an unsafe occupied location.
• Verify safe atmospheric conditions before authorized re-entry after a significant release.
• Do not use one universal ventilation airflow number for every machinery room.
• Follow adopted code/standard and engineered system design.

19. Flammable-Refrigerant Awareness Checklist

Modern HVAC/R refrigerants can include:

A2L
A2
A3

flammability classes.

High-Priority Rule

A2L
≠
A1

and:

LOWER FLAMMABILITY
≠
NONFLAMMABLE

19.1 Before Service

• Identify the exact refrigerant.
• Confirm the equipment was designed/approved for that refrigerant.
• Verify tool/recovery-machine/vacuum-pump/leak-detector compatibility.
• Verify recovery cylinder compatibility.
• Control ignition sources.
• Provide required ventilation.
• Follow charge-limit and service-procedure requirements.
• Follow manufacturer and adopted code requirements.
• Do not substitute a flammable refrigerant into equipment not designed for it merely because pressures appear similar.
• Do not use an ordinary non-rated tool merely because the connector fits.
• Do not use a torch until the system has been prepared for hot work by the approved procedure.
• Treat hydrocarbon refrigerants such as R-290/R-600a as A3 high-flammability refrigerants.

20. Electrical and Lockout/Tagout Checklist

HVAC/R service can involve:

• Line-voltage power.
• Control voltage.
• Capacitors.
• Motors.
• Compressors.
• Crankcase heaters.
• Electric resistance heaters.
• Pumps/fans.
• Stored mechanical pressure.
• Automatic restart.

OSHA’s hazardous-energy standard applies when unexpected energization/startup or release of stored energy during servicing can cause injury, subject to the standard’s scope and exceptions.

20.1 Before Servicing

• Identify all relevant energy sources.
• Shut down equipment using the approved procedure.
• Isolate energy at the actual energy-isolating device.
• Apply lockout/tagout according to the employer program where required.
• Verify de-energization using an appropriate test method.
• Discharge/control stored electrical energy where applicable.
• Control stored pressure and mechanical energy.
• Prevent automatic restart from thermostats, BAS commands, timers, pressure controls, or remote controls.
• Do not rely on a thermostat or control switch as the sole energy-isolating device when formal isolation is required.
• Restore guards and covers before returning equipment to service.
• Follow specific procedures when temporary energization is required for testing.

Important Distinction

OFF AT THERMOSTAT
≠
LOCKED OUT / ENERGY ISOLATED

21. Hermetic Compressor Under Vacuum Checklist

EPA Type II test topics specifically include:

SHOULDN'T ENERGIZE
HERMETIC COMPRESSORS
UNDER VACUUM

Therefore:

• Do not energize a hermetic compressor while the system is under a vacuum condition contrary to the manufacturer’s approved procedure.
• Restore the appropriate refrigerant/pressure condition before compressor operation.
• Follow manufacturer startup instructions after evacuation.
• Do not use compressor operation as a shortcut to replace proper recovery/evacuation procedure.

22. Type I Safety Checklist

For small-appliance service:

• Confirm appliance meets the complete Type I definition.
• Identify refrigerant before recovery.
• Install/use access fittings correctly.
• Use both high- and low-side access where required for failed-compressor recovery.
• Expect refrigerant/oil to remain trapped in the compressor.
• Keep hands/eyes away from process-stub discharge.
• Use recovery equipment appropriate to refrigerant and method.
• Do not use a disposable cylinder as a receiver.
• Control recovery-cylinder fill by weight.
• Remove temporary solderless access fittings at service conclusion as required by course guidance.
• Follow additional ignition-control procedures for hydrocarbon/A2L small appliances.

23. Type II Safety Checklist

For medium-, high-, and very-high-pressure appliances:

• Verify pressure category.
• Verify hoses/gauges/recovery machine are rated for expected pressure.
• Recover liquid first where appropriate to speed recovery.
• Recover vapor in addition to liquid.
• Never use system-dependent recovery equipment on >15-lb full-charge appliances unless permanently attached as an approved pump-out unit.
• Do not energize hermetic compressors under vacuum.
• Use dry nitrogen, regulator, and relief protection for pressure testing.
• Do not use oxygen or compressed air.
• Protect against high-pressure refrigerant release.
• Follow machinery-room controls for large systems.
• Follow applicable leak-repair/inspection requirements.
• Apply electrical/hazardous-energy control before opening machinery.

24. Type III / Low-Pressure Safety Checklist

Low-pressure chillers have several special hazards:

• Large refrigerant charge.
• Operation below atmospheric pressure.
• Air/moisture entry.
• Freeze risk.
• Water-side pressure.
• Refrigerant accumulation in machinery rooms.
• Oil containing dissolved refrigerant.
• Pressure-relief devices.

Before work:

• Verify refrigerant and low-pressure classification.
• Confirm machinery-room alarm/ventilation status.
• Evaluate atmospheric conditions.
• Avoid excessive pressurization during leak testing.
• Use approved low-pressure leak-test procedure.
• Prevent water freezing during recovery/evacuation.
• Circulate/remove water as required by the approved procedure.
• Heat oil only by the approved safe procedure; do not use uncontrolled flame.
• Remember the course Type III oil-heating exam value of 130°F where applicable.
• Verify pressure-relief devices and rupture-disc arrangements are intact.
• Do not defeat or improperly series-connect relief devices.
• Treat water boxes/pits/vessels as separate spaces requiring hazard evaluation.
• Apply lockout/hazardous-energy controls before internal mechanical work.

25. Water-Side and Freeze Hazards

Low-pressure chiller recovery can cool evaporator water enough to approach freezing.

• Maintain required water circulation during recovery where the procedure calls for it.
• Remove water where required to prevent freezing.
• Monitor water/refrigerant conditions.
• Do not allow trapped water to freeze and expand inside tubes/heat exchangers.
• Isolate and depressurize water-side systems before opening them.
• Do not treat the refrigerant side as the only stored-pressure hazard.

26. Pressure-Relief Device Checklist

Pressure-relief devices protect equipment from unsafe overpressure.

• Do not block, cap, or disable required relief devices.
• Do not install isolation that defeats required relief protection.
• Follow manufacturer/code requirements for discharge routing.
• Replace a rupture disc after activation as required.
• Investigate and correct the cause of an overpressure event.
• Do not assume two simple relief valves in series provide valid redundant protection.
• Keep discharge away from occupied/unsafe areas according to applicable design requirements.
• Use the actual appliance/code/manufacturer requirements for relief pressure and arrangement.

27. Cylinder and Equipment Damage Stop-Work Checklist

Stop work and isolate the area/equipment as appropriate if you observe:

• Bulged recovery cylinder.
• Severe corrosion.
• Fire/heat-damaged cylinder.
• Damaged cylinder valve.
• Hissing/leaking cylinder with unknown condition.
• Damaged recovery hose.
• Hose blistering/cuts.
• Gauge beyond rated range.
• Recovery machine high-pressure trips repeatedly.
• Unexpected refrigerant identity.
• Mixed/contaminated refrigerant suspected.
• Machinery-room alarm.
• Oxygen reading below safe threshold.
• Electrical arcing/burning odor.
• Unexpected overheating.
• Relief-device activation.
• Refrigerant decomposition/irritating odor after hot-surface exposure.

Do not defeat the safety device simply to finish the job.

28. Emergency Response Checklist

If a significant refrigerant release occurs:

DO NOT BECOME A SECOND VICTIM

• Stop work if safe to do so.
• Warn others.
• Leave the affected area.
• Follow site alarm/emergency procedure.
• Call trained emergency response when required.
• Do not enter/re-enter an oxygen-deficient, unknown, or heavily contaminated atmosphere without the required program, equipment, and authorization.
• Do not perform an impulsive confined-space rescue.
• Provide SDS/refrigerant identity to responders if available.
• Control ignition sources only if this can be done without unsafe exposure.
• Use emergency ventilation only as prescribed by the facility procedure.
• Verify atmosphere before authorized re-entry.
• Seek medical evaluation after significant inhalation, frostbite, eye exposure, or other serious exposure.

29. Safety Data Sheet Checklist

Know where to find critical SDS information.

Before service:

• Confirm the SDS matches the exact refrigerant/product.
• Review Section 2 hazards.
• Review Section 4 first aid.
• Review Section 8 PPE/exposure controls.
• Review Section 10 for incompatibilities/decomposition concerns.
• Use Section 14 as supporting transportation information, while current DOT requirements still control actual shipment.

30. Safety Classification Reminder

ASHRAE refrigerant safety groups combine:

TOXICITY
+
FLAMMABILITY

A
→ LOWER TOXICITY CLASS

B
→ HIGHER TOXICITY CLASS

1
→ NO FLAME PROPAGATION UNDER SPECIFIED TEST CONDITIONS

2L
→ LOWER FLAMMABILITY + LOW BURNING VELOCITY

2
→ LOWER FLAMMABILITY

3
→ HIGHER FLAMMABILITY

Examples already used in the course:

Do not infer:

A1
→ HARMLESS

or:

A2L
→ NONFLAMMABLE

31. High-Priority EPA 608 Safety Facts

Memorize these pairings:

REFRIGERANT LIQUID CONTACT
→ FROSTBITE

HIGH CONCENTRATION
→ OXYGEN DEPRIVATION / CARDIAC EFFECTS

EXTREME RESPIRATORY HAZARD
→ SCBA / APPROPRIATE ATMOSPHERE-SUPPLYING PROTECTION
under required program

LEAK TEST
→ DRY NITROGEN

NITROGEN
→ REGULATOR + RELIEF VALVE / RELIEF PROTECTION

OXYGEN / COMPRESSED AIR
→ DO NOT USE FOR REFRIGERANT-SYSTEM LEAK TESTING

HIGH TEMPERATURE
→ POSSIBLE TOXIC / CORROSIVE DECOMPOSITION PRODUCTS

RECOVERY CYLINDER
→ REFILLABLE
→ MONITOR FILL BY WEIGHT

DISPOSABLE CYLINDER
→ NEVER REFILL

CYLINDER >80% FULL
→ EXAM SAFETY HAZARD

O₂ <19.5%
→ OXYGEN DEFICIENT

A2L
→ LOWER FLAMMABILITY
→ NOT NONFLAMMABLE

HERMETIC COMPRESSOR
→ DO NOT ENERGIZE UNDER VACUUM

32. Common Mistakes and Confusing Points

Mistake 1 - Treating PPE as the First and Only Safety Control

PPE is important, but:

PPE
≠
SUBSTITUTE FOR VENTILATION / ENERGY ISOLATION / SAFE PROCEDURE

Mistake 2 - Assuming an A1 Refrigerant Cannot Create a Fire-Related Hazard

A nonflammability classification does not prevent high-temperature decomposition.

Mistake 3 - Assuming A2L Means Nonflammable

A2L is a flammability classification.

Ignition control still matters.

Mistake 4 - Using Compressed Air Because It Is “Mostly Nitrogen”

Compressed air contains oxygen and moisture.

It is not the dry-nitrogen pressure-test gas taught by EPA 608.

Mistake 5 - Connecting a Nitrogen Cylinder Without a Regulator

Cylinder pressure is far above normal test pressure.

Use the correct regulator and relief protection.

Mistake 6 - Treating a Relief Valve as the Regulator

The regulator controls intended test pressure.

The relief device is backup overpressure protection.

Mistake 7 - Relying on Smell to Determine Atmospheric Safety

Some refrigerants are difficult to detect by odor, and dangerous oxygen deficiency can exist without a reliable odor warning.

Use proper monitoring/evaluation.

Mistake 8 - Entering a Machinery Room Because the Fan Is Running

Ventilation operation does not prove the atmosphere is safe.

Mistake 9 - Treating Every Machinery Room as an OSHA Confined Space

Evaluate the actual space against the OSHA definition.

Mistake 10 - Treating SCBA as Normal Technician PPE

SCBA use requires specialized respiratory-protection/emergency procedures.

Mistake 11 - Heating a Recovery Cylinder With a Torch

Never use direct flame to accelerate refrigerant transfer.

Mistake 12 - Memorizing 125°F as a Universal DOT Cylinder Maximum

The current project deliberately does not teach that as a universal current DOT rule.

Follow actual cylinder/refrigerant/manufacturer and transportation requirements.

Mistake 13 - Using Cylinder Pressure to Judge Fill

Use weight.

A two-phase cylinder can remain near saturation pressure over a broad fill range.

Mistake 14 - Refilling a Disposable Cylinder

Never refill a disposable refrigerant cylinder.

Mistake 15 - Assuming a Thermostat Turns Off All Hazardous Energy

Use appropriate energy isolation/lockout procedures.

Mistake 16 - Energizing a Hermetic Compressor Under Vacuum

EPA Type II test topics specifically identify this as unsafe.

33. One-Minute Pre-Job Safety Review

Before touching the refrigerant circuit, ask:

WHAT REFRIGERANT?

WHAT PRESSURE?

WHAT SAFETY CLASS?

WHAT PPE?

WHAT ENERGY SOURCES?

IS THE AREA VENTILATED?

ANY ALARM?

ANY IGNITION SOURCE?

CORRECT RECOVERY EQUIPMENT?

CORRECT CYLINDER?

CYLINDER CAPACITY VERIFIED?

IF NITROGEN:
REGULATOR + RELIEF?

IF HOT WORK:
REFRIGERANT PROPERLY MANAGED?

IF CONFINED / UNKNOWN ATMOSPHERE:
AUTHORIZED ENTRY PROCEDURE?

If any answer is unknown:

STOP AND VERIFY

34. Student Readiness Checklist

A student should be able to answer Yes to every item before the Universal exam:

• I can explain why refrigerant causes frostbite.
• I know the difference between non-frozen eye exposure and frozen-tissue response.
• I know where SDS first-aid and PPE information are found.
• I understand oxygen displacement.
• I know that less than 19.5% oxygen is oxygen deficient under OSHA terminology.
• I know that a machinery room is not automatically an OSHA confined space.
• I understand that SCBA is specialized respiratory protection, not ordinary HVAC PPE.
• I recognize cardiac effects as a refrigerant exposure hazard.
• I know why refrigerant should be kept away from flame/hot surfaces.
• I understand that decomposition products depend on refrigerant chemistry.
• I know that phosgene is not a universal decomposition product of every refrigerant.
• I know that dry nitrogen is used instead of oxygen/compressed air for course leak testing.
• I know the purpose of the regulator.
• I know the purpose of downstream relief protection.
• I know recovery-cylinder and disposable-cylinder differences.
• I know why recovery cylinders are monitored by weight.
• I know the >80% cylinder-fill exam warning.
• I know why cylinders must be protected from heat.
• I know why a universal 125°F cylinder-storage rule is not used in this course.
• I understand cylinder restraint and valve protection.
• I understand refrigerant monitors versus oxygen monitors.
• I understand ventilation is not itself proof of a safe atmosphere.
• I can explain A1, A2L, A2, and A3 at the exam-recognition level.
• I understand why A2L tools/procedures must be refrigerant-compatible.
• I understand basic hazardous-energy/lockout concepts.
• I know not to energize a hermetic compressor under vacuum.
• I can identify Type I, II, and III special safety concerns.
• I know to stop work when the refrigerant, atmosphere, pressure, or energy state is uncertain.

35. Cross-Reference Guide

References

Current EPA Safety / Examination Sources

1. U.S. Environmental Protection Agency, Section 608 Test Topics, current page accessed August 14, 2026.
   https://www.epa.gov/section608/test-topics

2. U.S. Environmental Protection Agency, Refrigerant Safety, last updated March 5, 2026 and accessed August 14, 2026.
   https://www.epa.gov/snap/refrigerant-safety

3. U.S. Environmental Protection Agency, Questions and Answers About SNAP, current project verification August 14, 2026.
   https://www.epa.gov/snap/questions-and-answers-about-snap

Current OSHA Sources

4. Occupational Safety and Health Administration, 29 CFR 1910.132 - General Requirements, Personal Protective Equipment, current project verification August 14, 2026.
   https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.132

5. Occupational Safety and Health Administration, 29 CFR 1910.133 - Eye and Face Protection, accessed August 14, 2026.
   https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.133

6. Occupational Safety and Health Administration, 29 CFR 1910.138 - Hand Protection, accessed August 14, 2026.
   https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.138

7. Occupational Safety and Health Administration, 29 CFR 1910.134 - Respiratory Protection, accessed August 14, 2026.
   https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.134

8. Occupational Safety and Health Administration, 29 CFR 1910.146 - Permit-Required Confined Spaces, accessed August 14, 2026.
   https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.146

9. Occupational Safety and Health Administration, 29 CFR 1910.147 - The Control of Hazardous Energy (Lockout/Tagout), accessed August 14, 2026.
   https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.147

10. Occupational Safety and Health Administration, Clarification of OSHA’s Requirement for Breathing Air to Have at Least 19.5 Percent Oxygen Content, current interpretation used by this course.
    https://www.osha.gov/laws-regs/standardinterpretations/2007-04-02-0

Health / First-Aid Source Used by the Course

11. National Institute for Occupational Safety and Health, First Aid Procedures for Chemical Hazards, current course verification basis for chemical eye exposure and frozen-tissue response.
    https://www.cdc.gov/niosh/npg/firstaid.html

Current Cylinder / Transportation Sources

12. Electronic Code of Federal Regulations, 49 CFR § 173.301 - General Requirements for Shipment of Compressed Gases and Other Hazardous Materials in Cylinders, current project verification August 14, 2026.
    https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173/subpart-G/section-173.301

13. Electronic Code of Federal Regulations, 49 CFR § 173.301a - Additional General Requirements for Shipment of Specification Cylinders, current project verification August 14, 2026.
    https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173/subpart-G/section-173.301a

14. Electronic Code of Federal Regulations, 49 CFR Parts 171-180 - Hazardous Materials Regulations, current project verification August 14, 2026.

15. U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration, Safety Advisory Notice - Unauthorized Cylinders Used by HVAC Personnel and Service Technicians, January 2025.

Current Refrigeration-Safety Standard Context

16. ASHRAE, Refrigeration Resources - Standards 15 and 34, current project verification August 14, 2026.
    https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources

17. ASHRAE, Read-Only Versions of ASHRAE Standards, current project verification August 14, 2026.
    https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashrae-standards

Course Cross-References

18. 6.1 - Personal Protective Equipment and Refrigerant Exposure

19. 6.2 - Respiratory and Confined-Space Hazards

20. 6.3 - Fire Explosion and Decomposition Hazards

21. 6.4 - Refrigerant Safety Classifications

22. 6.5 - Nitrogen Pressure Testing

23. 6.7 - Machinery-Room Safety

24. 6.8 - Cylinder Shipping and Transportation

25. 8.10 - Type II Safety

26. 9.10 - Type III Safety and Machinery Rooms