单项选择题
The purpose of the safety relief valves installed on an auxiliary boiler is to （）.
A.relieve excess fuel oil pressure during the “off” fire cycle B.admit water to the dry pipe C.throttle the forced draft fan output for proper combustion D.reduce excess steam pressure in the boiler
单项选择题 The pH value of water in a diesel engine closed cooling water system should be maintained between （）.
单项选择题 Indirect cooling of fuel injector nozzle holders for diesel engines is accomplished primarily by （）.
单项选择题 In a diesel engine cooling water system, a pH of 60 indicates a/an （）.
