单项选择题 The refrigeration compressor in a water cooled refrigeration system is short cycling on the high pressure cutout switch， One reason for this could be the （）.

单项选择题 Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by（）.

单项选择题 Most pump manufacturers recommended that the discharge piping for centrifugal pumps be （）.