Refrigeration/ Air Conditioning Systems Flashcards
what is meant by the term pumping down?
removal of refrigerant before maintenance on a reciprocating system which is to be opened to the atmosphere
what is meant by the term pumping when dealing with refrigerant?
to release of air and non condensable gases from a system
what is meant by the term slugging?
the liquid refrigerant returning o the compressor causing noisy valves
what does the term low side refer to?
the part of system lying between the expansion valve and the suction valve of the compressor
the term frosting back refers to what?
the appearance of frost on the suction line extending as far back as the compressor
what NSTM would you use when researching refrigeration systems?
NSTM 516
what type of refrigeration compressors are used onboard naval ships?
reciprocating and centrifugal
the capacity of a reciprocating compressor plant is expressed in?
tons of refrigerant
all content high speed compressors operate at what RPM?
1750 rpm
what type of lube oil system would be found on a high speed compressor?
force feed lubrication
what is the purpose of a thermal expansion valves?
control the quantity of refrigerant that is admitted to the cooling coil and to reduce the pressure of the refrigerant
the load on the vapor compression air conditioning plant is determined by what?
the espied chill water temperature
two basic types of chilled water air conditioning systems are now in use, they are?
vapor compression and lithium bromide absorption
what purpose does the refrigerant compressor receiver serve?
acts as a surge tank and a temporary storage space for the liquid refrigeration
where is the dehydrator located in the refrigerant compressor system?
in the liquid refrigerant line between the TXV and the receiver
the dehydrator contains what type of drying agent?
silica gel or activated allumina
a pink indication on moisture indicator means?
excessive moisture has damaged the indicator, it must be replaced
proper refrigerant temperature of a space is maintained by what?
a solenoid valve and its related thermostatic switch
what automatically stops a refrigerant compressor when a failure of circulating water supply occurs?
water failure switch
the refrigerant liquid strainer is designed to protect what?
the solenoid valves and TXV
refrigerant piping is made of what material?
ACR seamless copper
nearly all hand operated valves in large refrigeration systems are packless for what reason?
to facilitate maintenance of the valves without valve removal
how are refrigerant leaks found?
by use of an electronic leak detector or by the soapsuds test
when properly tightened a V-belt can be depressed how far?
1/2 to 3/4 by the pressure of one finger at a point midway between the flywheel and the motor pulleys
is it allowable to use belt designs on a V belt?
Never
before handling refrigerant bottles you should read what NSTM?
NSTM 670
refrigerant cylinders must always be stowed in what manner?
in a cool, dry place, in an upright position
never allow a refrigerant cylinder to reach what temperature?
130 deg F
cylinder valves must always be protected by what?
cylinder tops
what must be done to a refrigerant cylinder when refrigerant has been discharged?
immediately weigh the cylinder and record the weight
refrigerants are considered to be deadly due to their composition of what?
halocarbons
is it ever allowable to mix refrigerant gases?
never
when measuring a certain space temperature, what two temperature readings determine air conditioning effectiveness?
wet bulb and dry bulb thermometer readings
dry bulb thermometer is a measurement of what?
sensible heat
what approval is required before using self contained air conditioners?
NAVSEA
what type of heat exchange is used in the lithium bromide absorption units?
regenerative type
what manual contains safety precaution for forces afloat when dealing with refrigerants and air conditioners?
OPNAVINST 5100.19 SERIES
what is the latent heat of fushion?
144 BTU’s
the most commonly used refrigeration systems used aboard ship is?
vapor compression type with reciprocating compressors
what purpose does the compressor in a refrigeration unit serve?
acts a pump
heat is absorbed by the refrigeration stored normally in what component?
the refrigerant evaporator
the float valves in a centrifugal refrigeration plant serves what purpose?
releases the refrigerant to the chiller
