27.The furnace of a oil fired boiler should be ____ before the operating burner is№
举一反三
- Before an auxiliary boiler is shutdown for an extended period of time， the water in the boiler should have a pH value of （）.
- Before operating the machine, we should carefully study the operator’s manual of a CNC machine tool.
- Before starting a diesel engine that has an engine driven lube oil pump， the engineer should （）.
- Radiation heat transfer of smoke tube boiler mainly occurs in , convection heat transfer mainly occurs in . A: Furnace and smoke pipe B: Smoke pipe and furnace C: Needle tube, smoke box D: Smoke box and smoke pipe
- The oil leaving the oil pump passes through the oil filter before it is circulated through the engine.