Topics: All categories in the pool
1: The heat picked up in the evaporator must equal to
- the heat giving by the condenser
- the heat gained by the condenser
- the heat lost by the medium being cooled
- the heat of compression
2: A VRF system is a direct system
- true
- false
3: There can be no airflow from an occupied space through a machine room unless what?
- System is high velocity
- System is ducted and sealed
- Duct is not located in the ceiling
- None of the above.
4: The measurement of heat in a particular substance is
- latent heat
- specific heat
- enthalpy
- sensible heat
5: A secondary coolant is defined as
- a low temperature refrigerant used for cascading systems
- any liquid used for the transmission of heat without a change of state in A/C refrigeration systems having flash point above 150F
- any refrigerant direcly in contact with the cooling space for process cooling
- a combination of interconnected parts from a closed circuit in where fluid is circulated for the purpose of cooling for a refrigeration system.
6: On a ammonia compressor, the pressure of a forced fed oil pump is changed by varying the
- opening at the pump outlet
- opening at the pump inlet
- cooling temperature set-point
- adjustment of the spring tension of the TXV
7: Which refrigerant is lighter than air?
- R-123
- R-717
- R-11
- R-134a
8: What does safe access mean?
- Locked doors
- A clear unobstructed path to the equipment and controls
- Well-lit exit signs
- OSHA approved
9: A compressor in which the increase in vapor pressure is attained without changing the internal volume of the compression chamber is called
- non-volumetric displacement compressor
- non-positive displacement compressor
- negative displacement compressor
- neutral chamber-type compressor
10: The critical temperature of a refrigerant gas occurs when
- any increase in pressure will not liquefy the gas
- any decrease in pressure will cause condensation
- the gas returns to a liquid
- the gas is no longer saturated
11: When using nitrogen for brazing, the pressure should be:
- Very low
- Slightly below atmospheric
- 50-100 psig
- 125 psig
12: Class A refrigerants are considered
- non-toxic
- toxic
- non-flammable
- flammable
13: A Category D fluid
- is when the fluid handled is non flammable, nontoxic, and not damaging to human as defined in ANSI/ASME Process Piping.
- is when the design pressure does not exceed 150 psi
- a fluid for service piping in which the potential for personnel exposure is judged to cause harm and irreversible damage to those persons exposed to it
- Both a and b are correct
14: Low ambient controls are used when
- when systems run all year round
- economizers are used
- always
- on air conditioning systems only
15: A pressure-limiting device isn't required on a factory-sealed system containing less than ____ lbs.
- 25
- 22
- 66
- 50
16: Low-side system leaks in a low-pressure chiller will often result in
- water being pulled into the system
- system refrigerant leaking from the system
- nitrogen leaking out of the system.
- air being pulled into the system
17: An example of an "Expendable Refrigerant" is
- liquid nitrogen
- lithium bromide
- liquid oxygen
- ammonia
18: Sublimation occurs when
- ice melts and turns to water
- liquid is formed from a gas
- gas is formed directly from a solid
- gas is formed from a liquid
19: Can ammonia be used on domestic system?
- yes
- no, unless there is proper ventilation system installed
- no
- yes, for systems under 10 tons
20: If the suction pressure is low and the evaporator temperature high, the cause will be a?
- too small evaporator
- overcharged
- compressor suction valve stuck open
- starved evaporator
21: When this is installed on the high side of a system, it must be capable of reading 1.2 times the design pressure (ASHRAE 15 9.11.3)
- Pressure gauge
- Temperature gauge
- Sight glass gauge
- All of the above
22: A 120 volt motor rated at 1,800 watts. You find the motor is drawings 25 amps. The motor is
- drawing RLA and is running as it should
- drawing LRA and is seized and should be replaced.
- running hot
- none of the above
23: Fractionation occurs when
- when a fraction of refrigerant is added as the full charge
- the pressures increase as the heat load increases
- the pressures decreases as the heat load decreases
- some of the blended refrigerant evaporates or condenses before the rest of the blend
24: When energized, a normally open relay will be
- open
- depends on the type and class of the relay
- noisy
- closed
25: A chilled water pump's suction gauge reads 10 psig. The discharge gauge reads 48 psig. What is the head in feet the pump is working against?
- 38
- 96
- 88
- 58