The type of gauge most commonly used to measure pressure is the （）.

单项选择题When refrigerant leaves the receiver, it flows next on to the （）.

A.evaporator coils
B.liquid strainer
C.compressor
D.condenser

单项选择题A compound gauge is typically installed on the （）.

A.suction side of a bilge pump
B.exhaust manifold of an auxiliary diesel
C.discharge line from an air compressor
D.chemical feed tank of an evaporator

单项选择题Which of the listed statements is correct concerning the starting of centrifugal pumps?（）

A.They should always be started with the discharge valve closed
B.They should always be started with the discharge valve opened
C.A priming pump is always required to flood the impeller suction
D.They should always be started with the sealing line valves closed

单项选择题Excessive oil foaming in the crankcase of a refrigeration compressor at start up can cause（）.

A.compressor damage from improper lubrication
B.refrigerant absorption by the lubricant
C.increased viscosity in the lubricant
D.carbon deposit on the compressor suction valves

单项选择题Which of the valves listed is NOT considered to be a hydraulic system directional control valve?（）

A.Spring-centered valve
B.Unloading valve
C.Three-position valve
D.Two-position valve