更多"When it is necessary to open a refr"的相关试题:
[单项选择]Zinc rods are installed in the refrigeration system （）.
A. liquid strainer
B. liquid receiver
C. saltwater condenser
D. evaporator
[单项选择]When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
A. increase the amount of cooling water to the condenser
B. decrease the amount of cooling water to the condenser
C. add more refrigerant to the system
D. remove some refrigerant from the system
[单项选择]When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is a （）.
A. loose expansion valve control bulb
B. low differential setting on the H-Pcutout
C. blown fuse in the motor circuit
D. faulty suction pressure regulator
[单项选择]When the refrigeration demand is small,（）
A. the expansion valve will move toward the wide open position
B. the expansion valve will move toward the closing position
C. the feeler bulb will conveys the high temperature
D. the superheat degree will raise
[单项选择]When adding oil to a refrigeration system, precautions must be taken to ensure that （）.
A. the compressor suction pressure is not too high
B. all air is purged from the pump and charging fittings
C. the high pressure cutout switch is held open to prevent accidental starting
D. the condenser is completely shutdown first
[单项选择]A refrigeration unit will tend to short cycle when operating （）.
A. under heavy loads
B. during hot gas defrost
C. under light loads
D. during starting conditions
[单项选择]When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.
A. always be wide open when the compressor restarts
B. continue to operate as if the system were in operation
C. remain open until evaporator pressure equalizes, then close until the compressor restarts
D. always be completely closed until the compressor restarts
[单项选择]If found oil when we open low oil level plug of separator, it indicates （）
A. the separator is overload
B. the monitor equipment of separator fails
C. the discharge pump of separator can not work
D. the temperature of oil water is low
[单项选择]When anchoring in open anchorage, chief engineer should consult with captain （）
A. if the ship must be stand by
B. if M-E should be stopped
C. if keep-watching as in voyage
D. if the ship must anchor two anchors
[单项选择]When launching an open lifeboat by falls，the boathooks should be（）.
A. secured forward and aft where readily available
B. secured amidships where they will not hinder the personnel
C. used for fending off
D. used for picking up survivors in the water
[单项选择]The needle valve will open when the fuel pressure acting on the needle valve （） exerts a sufficient force to overcome the spring compression.
A. tape face
B. tapered face
C. surface
D. thinner face
[单项选择]When towing in an open seaway，it is important to use a towing line（）.
A. made only of wire rope，due to possible weather conditions
B. that will have the tow on a crest while your vessel is in a trough
C. that will have the tow on a crest while your vessel is on a crest
D. with little dip to gain maximum control of the tow
[单项选择]When subjected to high heat from a open flame, or an electric heating element, which of the listed refrigerants will break down and produce phosgene gas?（）
A. CO2
B. Methyl chloride
C. R-22
D. Sulphur dioxide
[单项选择]Accidental grounds in a shipboard electrical system must be repaired as soon as possible as they will （）
A. result in immediate power outages
B. damage circuit breakers
C. appear on the ground detection system
D. damage insulation and may cause outages
[单项选择]Refrigeration system compressor crankcase sweating is an indication of （）.
A. insufficient lube oil circulating through the system
B. excessive circulation of lube oil through the system
C. insufficient refrigerant in the system
D. an overworked compressor
[单项选择]In a closed diesel engine freshwater cooling system, the amount of coolant flowing through the heat exchanger is controlled by the （）.
A. suction pressure regulator
B. thermostatic bypass valve
C. sea water temperature
D. water level in the expansion tank
[单项选择]Water allowed to accumulate in the hydraulic system oil will cause an oxidation process producing by- products which are normally （）.
A. gums, acids, and varnishes
B. removed by cellulose type filters
C. neutralized by oil additives
D. not removed by absorbent filters
[单项选择]SOLAS regulations require that the inert gas system shall be capable of delivering inert gas with an oxygen content of not more than what percentage?（）
A. 5%
B. 8%
C. 6%
D. 3%
[单项选择]Insufficient refrigerant in a refrigeration plant may result in （）.
A. high discharge pressure
B. frosting of the crankcase
C. high temperature of the overboard water
D. low suction pressure of compressor
