The mercury tube in a pressure control must be inspected at least ___ for mercury vaporization.

A thermodynamic steam trap opens and closes by a single ___ that rises to allow the discharge of air and cool condensate.

The two types of draft produced in a boiler are mechanical and forced.

A steam trap that fails to open causes a heating unit to become ___.

The range of pressure on a vacuum switch is usually ___.

Air or gases flow from a location of low pressure to a location of high pressure.

Air or gases flow from a location of low pressure to a location of high pressure.

Sensible heat is heat that ___.

___ combustion is combustion that occurs when fuel is burned using only the theoretical amount of air.

The ___ are environmental standards for ambient pollutant emissions from new sources of emissions.