33. which of the following is true regarding ...
33. which of the following is true regarding lower flammability hfo refrigerants a. they can be vented to the atmosphere. b. they cannot be reclaimed. c. they must be charged as a liquid. d. they must be recovered. 34. which of the following refrigerants is an hfo? a. r - 32 b. r - 290 c. r - 600a d. r - 1234yf 35. the rate at which a flame front spreads relative to the unburned gas ahead the; a. burning velocity. b. heat of combustion. c. lower flammability limit. d. minimum ignition energy. 36. which of the following is one of the factors used to determine the maxir an a2l system? a. the average relative humidity of the installation space. b. the outdoor ambient air design temperature. c. the cubic feet of airspace served by the equipment. d. the size of the supply and return air ducts. 7. upon completion of an a2l system installation; a. a permanent label must be placed on the system to show require b. the fire suppression system must be tested to ensure proper ope c. the manufacturer’s literature must be kept on file by the contrac installation. d. the manufacturer’s literature should be reviewed with and left w
Answer
# Brief Explanations:
## Question 33:
Lower - flammability HFO refrigerants must be recovered to prevent environmental and safety issues. They cannot be vented to the atmosphere, can be reclaimed, and are charged as a liquid.
## Question 34:
R - 1234yf is an HFO refrigerant. R - 32 is a hydrofluorocarbon (HFC), R - 290 is propane (a hydrocarbon), and R - 600a is isobutane (a hydrocarbon).
## Question 35:
The rate at which a flame front spreads relative to the unburned gas ahead is the burning velocity. Heat of combustion is the amount of heat released during combustion, lower flammability limit is the minimum concentration of a gas in air that can burn, and minimum ignition energy is the minimum energy required to ignite a gas - air mixture.
## Question 36:
The cubic feet of airspace served by the equipment is a factor used to determine the maximum charge in an A2L system. Humidity, outdoor temperature, and duct size are not primary factors for determining the maximum charge.
## Question 37:
Upon completion of an A2L system installation, a permanent label must be placed on the system to show requirements. Testing the fire - suppression system is not directly related to the completion of A2L system installation, and while keeping or reviewing manufacturer's literature is important, the key requirement is the placement of the label.
# Answer:
33. D. They must be recovered.
34. D. R - 1234yf
35. A. burning velocity.
36. C. The cubic feet of airspace served by the equipment.
37. A. a permanent label must be placed on the system to show requirements.