RSES Safety Practices & Regulatory Compliance 5 — Questions and Answers
Question 1: What is the safe oxygen level range for a technician working in a confined space with refrigerant present?
- 14% to 16%
- 16% to 18%
- 19.5% to 23.5% (Correct answer)
- 24% to 26%
Correct answer: 19.5% to 23.5%
OSHA requires atmospheric oxygen concentration in confined spaces to be between 19.5% and 23.5%; below 19.5% is oxygen-deficient and above 23.5% is oxygen-enriched.
Question 2: Under EPA Section 608, refrigerant sales of CFC and HCFC refrigerants in containers larger than 2 lbs are restricted to:
- Any licensed HVACR contractor
- Technicians certified under Section 608 (Correct answer)
- Businesses registered with the EPA
- Individuals with a valid state HVACR license only
Correct answer: Technicians certified under Section 608
EPA 608 restricts the purchase of CFC and HCFC refrigerants in containers larger than 2 lbs to certified technicians or persons working under their direct supervision.
Question 3: What is the function of a 'fusible plug' on a refrigerant cylinder?
- It seals the valve outlet when the cylinder is empty
- It melts at a specific temperature to relieve pressure before cylinder rupture (Correct answer)
- It prevents unauthorized refilling of disposable cylinders
- It indicates when the cylinder has been previously used
Correct answer: It melts at a specific temperature to relieve pressure before cylinder rupture
A fusible plug is a pressure-relief device filled with a low-melting alloy that melts at elevated temperatures, venting the cylinder before pressure causes catastrophic failure.
Question 4: Which refrigerant class poses the greatest immediate danger of chemical burns and respiratory damage at low concentrations?
- HFCs (e.g., R-134a)
- HCFCs (e.g., R-22)
- Natural refrigerants — ammonia (R-717) (Correct answer)
- Natural refrigerants — CO2 (R-744)
Correct answer: Natural refrigerants — ammonia (R-717)
Ammonia (R-717) is immediately dangerous to life and health (IDLH) at 300 ppm and can cause severe burns to eyes, skin, and respiratory tract at relatively low concentrations.
Question 5: A technician discovers a system has been charged with an unknown refrigerant blend. What is the safest course of action?
- Add the refrigerant labeled on the nameplate and top up the system
- Recover the entire charge without mixing, label the cylinder 'unknown mixture', and have it analyzed (Correct answer)
- Vent the charge and recharge with a known refrigerant
- Identify the refrigerant using smell and proceed with the nearest match
Correct answer: Recover the entire charge without mixing, label the cylinder 'unknown mixture', and have it analyzed
Unknown blends must be fully recovered into a dedicated cylinder labeled 'unknown mixture' and sent for analysis; mixing refrigerants is prohibited and creates hazardous conditions.
Question 6: What does the Montreal Protocol primarily regulate?
- Energy efficiency standards for refrigeration equipment globally
- The production and consumption of ozone-depleting substances (Correct answer)
- Refrigerant leak detection thresholds for commercial systems
- International transportation requirements for refrigerant cylinders
Correct answer: The production and consumption of ozone-depleting substances
The Montreal Protocol is an international treaty that phases out the production and consumption of substances that deplete the stratospheric ozone layer, including CFCs and HCFCs.
Question 7: When must a refrigerant leak inspection report be filed with the EPA for a comfort cooling appliance?
- Whenever any leak is detected regardless of charge size
- When a system with a charge of 50 lbs or more has a leak rate exceeding 10% per year (Correct answer)
- When a system with a charge over 5 lbs leaks more than 30% per year
- Only when the system fails the annual mandatory inspection
Correct answer: When a system with a charge of 50 lbs or more has a leak rate exceeding 10% per year
Under EPA 608, systems with a full charge of 50 lbs or more that exceed the applicable leak rate threshold for comfort cooling (10% annually) require leak inspection and repair records.
RSES Safety Practices & Regulatory Compliance 5
What is the safe oxygen level range for a technician working in a confined space with refrigerant present?