RSES Safety Procedures 2 — Questions and Answers
Question 1: When using a manifold gauge set on a refrigeration system, what is the correct procedure before connecting to the system?
- Connect gauges with the system running at full load
- Purge the gauge hoses with refrigerant to remove air and moisture (Correct answer)
- Open both hand valves fully before attaching to system ports
- Check oil level in the compressor first
Correct answer: Purge the gauge hoses with refrigerant to remove air and moisture
Purging gauge hoses removes air and moisture that could contaminate the refrigerant system or give inaccurate readings.
Question 2: What is the minimum recommended safety relief valve setting for a high-pressure refrigerant system using R-22?
- 150 psig
- 200 psig
- 250 psig
- 350 psig (Correct answer)
Correct answer: 350 psig
ASHRAE and safety codes require relief valves on R-22 high-side equipment to be set at no more than the maximum allowable working pressure, typically 350 psig for R-22 high-side components.
Question 3: A technician discovers refrigerant oil on the floor near a refrigeration unit. What is the FIRST safety action to take?
- Immediately add oil to the system to compensate for the loss
- Identify and eliminate any ignition sources in the area (Correct answer)
- Run the system to check if the leak self-seals under pressure
- Increase system operating pressure to locate the source
Correct answer: Identify and eliminate any ignition sources in the area
Oil on the floor near refrigeration equipment can create slip hazards and may contain refrigerant; eliminating ignition sources is the first priority if flammable refrigerants are involved.
Question 4: Which color-coded cylinder should NEVER be refilled and is intended for single use only?
- Gray cylinders used for recovered refrigerant
- Yellow cylinders used for R-134a
- White cylinders used for R-22
- Disposable small cylinders with a non-refillable valve (Correct answer)
Correct answer: Disposable small cylinders with a non-refillable valve
Disposable refrigerant cylinders are designed for single use and are illegal to refill; they are identified by their non-refillable valves.
Question 5: What does a pressure-enthalpy diagram primarily help a refrigeration technician determine regarding safety?
- The correct torque settings for flare fittings
- Whether system pressures are within safe operating limits for the refrigerant (Correct answer)
- The proper PPE required for service work
- The maximum electrical amperage draw of the compressor
Correct answer: Whether system pressures are within safe operating limits for the refrigerant
A pressure-enthalpy diagram shows saturation curves and operating conditions, helping technicians verify that system pressures stay within safe limits for the specific refrigerant.
Question 6: When brazing refrigerant lines, what gas must flow through the tubing to prevent oxide scale formation and reduce fire risk?
- Compressed air at low pressure
- Dry nitrogen at a low positive pressure (Correct answer)
- Carbon dioxide at system operating pressure
- Oxygen-acetylene mixture at reduced flow
Correct answer: Dry nitrogen at a low positive pressure
Dry nitrogen purged through tubing during brazing prevents internal oxidation scale and keeps flammable refrigerant vapors purged from the work area.
Question 7: A technician is working in a confined mechanical room where refrigerant concentration may be elevated. Which symptom indicates that the oxygen level may be dangerously low?
- Increased sweating and elevated heart rate
- Dizziness, rapid breathing, and impaired judgment (Correct answer)
- Strong chemical odor from the refrigerant
- Pressure relief valves venting repeatedly
Correct answer: Dizziness, rapid breathing, and impaired judgment
Dizziness, rapid breathing, and impaired judgment are early symptoms of oxygen displacement (hypoxia) caused by refrigerant or other gases displacing oxygen in a confined space.
RSES Safety Procedures 2
When using a manifold gauge set on a refrigeration system, what is the correct procedure before connecting to the system?