单项选择题
A.microscopic steel shavings B.abrasive waste C.anti-oxidant compounds D.oxidation by-products
If the thermal bulb of an expansion valve is incorrectl...
单项选择题If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
A.increase the capacity of the coil B.increase the superheat at the bulb C.deliver more refrigerant to the coil D.decrease the capacity of the coil
Which of the listed pumps is NOT a positive displacemen...
单项选择题Which of the listed pumps is NOT a positive displacement pump?（）
A.Centrifugal B.Reciprocating C.Gear D.Rotary
Heavy wear in a particular area of the inner circumfere...
单项选择题Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
A.a high suction head B.rotating rings C.badly worn bearings D.a loose stuffing box gland
