FDNY Z-51 EXAM |251 QUESTIONS FULLY SOLVED & UPDATED 2023.|GUARANTEED SUCCESS

The efficiency of the refrigerant cycle is affected by the operation of the condenser. Of the following, a more efficient centrifugal compressor operation results from Lowering the condenser pressure In most semi hermetic compressors, the suction vapor is used too Cool's the motor The amount of refrigerant that flows through the orifices of an economizer is determined by the Difference between the high side and the low side pressure the instalation of an inline refrigerant cleaning system is advisable to remove impurities from the system a refrigerant engineer verifies that a condenser pump is cavitating of the following the most likely cause for this condition is: a faulty cooling tower water level controller when an expansion valve is operating properly, at the end of the evaporator will contain only superheated vapor a centrifugal water pump is considered to be fully primed when the pump is full of liquid A refrigeration compressor has failed to turn on. the engineer on duty verifies the electrical circuit to the motor, including all switches and circuit breakers is complete, according to recomended service practice, the next item to be checked would likely be the: temperature and pressure controls Refrigerants are characterized by their physical properties including Flashpoint, refrigeration effect and others, of the refrigerants in commercial and industrial the highest latent heat and refrigerant effect is: ammonia which of the following ashrae refrigerant safety classification which is most toxic B3 which of the following ashrae refrigerant safety classification is the most flammable A3 in q indirect refrigeration system,of the following, the one that would not be used as a cooling medium for building spaces being cooled is r-22 (cooling medium= glycol or any brine solution) the primary way of achieving capacity control of a an centrifugal compressor is by: adjustment of the inlet impeller pre-rotational vanes regarding the functioning of a steam turbine, why is it advisable to keep moisture in the inlet low as possible keeps turbine blades wear to minimum a water chiller is equipped with a reciprocating compressor, a thermostatic expansion valve and a an air cooled condenser. A restriction in the refrigerant line would result in high suction super heat the process by which refrigerant is extracted and cleaned for reuse without requirements for reclamation is called recycle the purpose of wear rings in a centrifugal pump is to prevent wearing of the pump housing and impeller a centrifugal compressor is in operation with suction pressure is 3 psig and the discharge is 10psi what is the atmospheric pressure is 14.7 which is the ratio closest to 1.39 Ratio= discharge pressure ((PSIA ÷ Sucction Pressure PSIA÷ PSIA electrical current is measured in amperes how would you put an additional pump online open suction valve, open discharge valve gradually of the following, the major advantage of a shell and coil condenser is there is less danger of developing leaks an engineer needs to vary the flow of refrigerant in a refrigeration system, which operation in the flow of the system does not include solenoid valve thermal bull is attached to the suction plate between the evaporator cokl and the compressor by an insulated line. assume that the machine room is 85° F. a break down of the insulation results in: flooding of the evaporator water and moisture is serious problem in a refrigerant system how to avoid proper evaluation at the charging of the system while on duty a refrigeration engineer notic That the suction line to the compressor and part of the compressor itself is frosted over the following the most likely reason for this condition would be There is not enough Refrigerant in the system While doing a routine inspection the engineer notices the bulb of the TXV on the floor. The refrigerant engineer should have attached a bulb at the The outlet end of the coil A refrigerant engineer verifies that a chilled water pump is cavity to of the following the most likely cause for this condition is Water leaks through the mechanical seals The only refrigerant/temperature chart available to a refrigeration engineer lists the temperature In ﾟC if the chart indicates a Celsius temperature of 4ﾟ this is equivalent to 39.2ﾟ F° Temp= C° × 1.8 + 32= 4×1.8= 7.2+32=39.2 F° Convert + 32 C°Convert - 32 C° = F(Temp) - 32° ÷1.8 The use of oil in the refrigeration machine is to Reduce wear and friction in the compressor parts Which of the following will connect to the Middle port on a gauge manifold Vacuum pump There is a decrease in efficiency of a reciprocating compressor. The most likely is caused by Leaking suction valve The suction and discharge valve of the reciprocating compressor are mounted as follows Discharge valve on top of the valve plate and suction valve on the bottom A high side float is used to maintain Constant level of refrigerant in the evaporator Which of these compressors is non positive type compressor displacement Centrifugal When is emergency power not required according to code Data centers What is the most widely used regulation book by operating engineers EPA What type of refrigerant do you need FDNY approval for Propane(( Flammable's )) Centrifugal pressure is determined by Speed of motor Liquid refrigerant that has passed through a metering device is at Low pressure saturated liquid What is the advantage of a shell and tube condenser as opposed to a shell and coil condenser Better heat transfer Where is the muffler located Between the compressor and condenser