A reciprocating air compressor is running roughly and vibrating excessively, indicating that the()。

[单选题]If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably _____.A．misalignment or worn main bearingsB．insufficient cylinder lubricationC．defective or poorly fitted valvesD．All of the above

In a chilled water air conditioning unit using a reciprocating compressor, the r

[单选题]The loss of （） from an air compressor could lead to an overheated air discharge and possibly an explosion in the pipelines leading to the air reservoir.A . lubricating oilB . compressed airC . cooling waterD . sealing ring

[单选题]If the head pressure of a reciprocating refrigeration compressor is excessiveA．the relief valve should open before the high pressure cutoutB．the relief valve should open and allow the excess refrigerant to flow to the receiverC．the high pressure cuto

[单选题]If the refrigeration compressor crankcase is sweating, the cause may be due toA．a shortage of refrigerantB．the compressor running continuouslyC．liquid refrigerant returning to the compressorD．the compressor short cycling on the high pressure cutout

[单选题]Oil oxidation as a result of excessively high lube oil temperature, is harmful to a diesel engine BecauseA．oil foaming will always occurB．large quantities of oil are consumedC．lube oil viscosity is always decreasedD．corrosive by-products are usually

[单选题]To successfully reduce an excessively high diesel engine exhaust gas temperature, you should （）.A . reduce the engine driven fuel pump outlet pressureB . retard the fuel injector timing to reduce powerC . increase the fuel rack settingD . reduce the

[单选题]If a refrigeration compressor is short cycling on high head pressure, you shouldA．purge the condenser if the waterside is dirtyB．check for proper water flow through the condenserC．increase the high pressure cutout settingD．reduce the cooling water fl

[单选题]If a refrigeration compressor is short cycling on high head pressure, you should _______.A．purge the condenser if the waterside is dirtyB．check for proper water flow through the condenserC．increase the high pressure cutout settingD．reduce the cooling

[单选题]Low compressor head pressure in a refrigeration system can be caused by ___.A．insufficient condenser cooling waterB．excessive condenser cooling waterC．air in the refrigeration systemD．excessive refrigerant in the system