A(n) ___ is an air pressure-activated switch that closes after proving sufficient pressure of combustion air from the forced draft fan.

Without condensate in a surge tank, the low water alarm on the tank should sound.

A low limit control is a pressure control that senses steam pressure and automatically shuts down a burner if the operating control fails.

The ASME Boiler and Pressure Vessel Code requires at least one water column on all boilers.

___ can result in bags and blisters.

Hot water boilers use ___ instead of the bottom blowdown valves used with steam boilers.

The scales used on diaphragm gauges vary from hundredths of an inch to several inches of ___, depending on the pressure being measured.

___ is the exposure to highly alkaline elements, causing boiler metal corrosion at stress zones.

A mercury-tube pressure control is a pressure control that regulates a burner control circuit by the flow of mercury in a mercury tube.

A mercury-tube pressure control is a pressure control that regulates a burner control circuit by the flow of mercury in a mercury tube.