Q-01 FDNY (Electrical Engineering) STUDY
EXAM QUESTIONS AND ANSWERS RATED A
An atmospheric line on an indicator card from the head of a double-
acting, single stage horizontal ammonia compressor is used
(A) to record piston stroke.
(B) to record volumetric efficiency.
(C) to record compressor superheat.
(D) as a pressure reference or standard.
Correct Answer -(D) as a pressure reference or standard.
A compressor may lose oil if
(A) there is air in the system
(B) the velocity of refrigerant in the risers is too low.
(C) there are medium pressure drops in the evaporator.
(D) There are small load variations in the system.
Correct Answer -(B) the velocity of refrigerant in the risers is too low.
When charging, the best way to determine the quantity of refrigerant in
the system is to
(A) open the petcock on the liquid receiver.
(B) weigh the cylinder charge of the refrigerant.
(C) feel the temperature charge of the receiver shell.
(D) put a gas meter on the liquid line.
Correct Answer -(B) weigh the cylinder charge of the refrigerant.
,Which of the following would not help determine compressor
displacement?
(A) Length of the piston.
(B) Revolution per minute.
(C) Diameter of piston.
(D) Number of cylinders.
Correct Answer -(A) Length of the piston.
In a lithium bromide absorption system producing chilled water, the
lowest possible temperature leaving the evaporator is
(A) 31*F
(B) 33*F
(C) 35*F
(D) 38*F
Correct Answer -(D) 38*F
If brine becomes saturated with ammonia in a small compression plant,
the proper thing to do is
(A) run the brine through the cooling tower and treat it with lime.
(B) treat the brine with lime.
(C) run it to the sewer and make a new batch.
(D) pay no attention to the problem since it will correct itself.
Correct Answer -(C) run it to the sewer and make a new batch.
The main reason for purging a Freon centrifugal refrigerating system is to
remove
(A) water lubricating oil.
,(B) gaseous lubricating oil.
(C) noncondensable gas.
(D) water vapor.
Correct Answer -(C) noncondensable gas.
In an absorption system, refrigerant boils in the
(A) absorber.
(B) evaporator.
(C) condenser.
(D) generator.
Correct Answer -(B) evaporator.
Purging a double-pipe condenser should be done from the
(A) bottom, near the liquid refrigerant outlet.
(B) middle, on one of the bands.
(C) top, near the gas inlet.
(D) relief valve by the outlet of the liquid line.
Correct Answer -(C) top, near the gas inlet.
Formula for piston speed
Correct Answer -PS = (2 x Stroke x RPM)/12
The strength of strong liquor in an absorption system decreases as the
(A) expansion valve is opened.
(B) condenser pressure decreases.
(C) evaporator load increases.
, (D) evaporator load decreases.
Correct Answer -(D) evaporator load decreases.
When a moisture-saturated refrigerant is __________, water is released.
Correct Answer -
The temperature on a wet-bulb thermometer equals the dry-bulb
temperature when
(A) the air below is freezing.
(B) the air is saturated with moisture.
(C) the air has no moisture.
(D) this can never happen.
Correct Answer -(A) the air below is freezing.
Carbonate desposits from brine on ice cans can be controlled to great
extent by
(A) adding sodium dichromate to the brine.
(B) increasing the pH to 8 for a period of time.
(C) adding calcium chloride to the brine solution.
(D) decreasing the pH to slightly under 7 for a period of time.
Correct Answer -(D) decreasing the pH to slightly under 7 for a period of
time.
A desirable property of ammonia refrigerant oil is
(A) high paraffin content.
(B) being free of water.
(C) very low flashpoint.
EXAM QUESTIONS AND ANSWERS RATED A
An atmospheric line on an indicator card from the head of a double-
acting, single stage horizontal ammonia compressor is used
(A) to record piston stroke.
(B) to record volumetric efficiency.
(C) to record compressor superheat.
(D) as a pressure reference or standard.
Correct Answer -(D) as a pressure reference or standard.
A compressor may lose oil if
(A) there is air in the system
(B) the velocity of refrigerant in the risers is too low.
(C) there are medium pressure drops in the evaporator.
(D) There are small load variations in the system.
Correct Answer -(B) the velocity of refrigerant in the risers is too low.
When charging, the best way to determine the quantity of refrigerant in
the system is to
(A) open the petcock on the liquid receiver.
(B) weigh the cylinder charge of the refrigerant.
(C) feel the temperature charge of the receiver shell.
(D) put a gas meter on the liquid line.
Correct Answer -(B) weigh the cylinder charge of the refrigerant.
,Which of the following would not help determine compressor
displacement?
(A) Length of the piston.
(B) Revolution per minute.
(C) Diameter of piston.
(D) Number of cylinders.
Correct Answer -(A) Length of the piston.
In a lithium bromide absorption system producing chilled water, the
lowest possible temperature leaving the evaporator is
(A) 31*F
(B) 33*F
(C) 35*F
(D) 38*F
Correct Answer -(D) 38*F
If brine becomes saturated with ammonia in a small compression plant,
the proper thing to do is
(A) run the brine through the cooling tower and treat it with lime.
(B) treat the brine with lime.
(C) run it to the sewer and make a new batch.
(D) pay no attention to the problem since it will correct itself.
Correct Answer -(C) run it to the sewer and make a new batch.
The main reason for purging a Freon centrifugal refrigerating system is to
remove
(A) water lubricating oil.
,(B) gaseous lubricating oil.
(C) noncondensable gas.
(D) water vapor.
Correct Answer -(C) noncondensable gas.
In an absorption system, refrigerant boils in the
(A) absorber.
(B) evaporator.
(C) condenser.
(D) generator.
Correct Answer -(B) evaporator.
Purging a double-pipe condenser should be done from the
(A) bottom, near the liquid refrigerant outlet.
(B) middle, on one of the bands.
(C) top, near the gas inlet.
(D) relief valve by the outlet of the liquid line.
Correct Answer -(C) top, near the gas inlet.
Formula for piston speed
Correct Answer -PS = (2 x Stroke x RPM)/12
The strength of strong liquor in an absorption system decreases as the
(A) expansion valve is opened.
(B) condenser pressure decreases.
(C) evaporator load increases.
, (D) evaporator load decreases.
Correct Answer -(D) evaporator load decreases.
When a moisture-saturated refrigerant is __________, water is released.
Correct Answer -
The temperature on a wet-bulb thermometer equals the dry-bulb
temperature when
(A) the air below is freezing.
(B) the air is saturated with moisture.
(C) the air has no moisture.
(D) this can never happen.
Correct Answer -(A) the air below is freezing.
Carbonate desposits from brine on ice cans can be controlled to great
extent by
(A) adding sodium dichromate to the brine.
(B) increasing the pH to 8 for a period of time.
(C) adding calcium chloride to the brine solution.
(D) decreasing the pH to slightly under 7 for a period of time.
Correct Answer -(D) decreasing the pH to slightly under 7 for a period of
time.
A desirable property of ammonia refrigerant oil is
(A) high paraffin content.
(B) being free of water.
(C) very low flashpoint.
