Flash Steam - the re-evaporation of condensate back to steam. It occurs when
condensate flows into a reduced pressure area where the condensate’s temperature
is above boiling point for that reduced pressure. For example: if hot condensate is
discharged by a trap into a low pressure return, a certain percentage of that condensate
will be immediately transformed into steam.
Foaming - a condition that occurs when oil, organic materials and other substances
contaminate the boiler water causing froth to build up on the surface water in a boiler.
This leads to wetter steam, lower efficiency and the water level bouncing in the gauge
glass.
Float and Thermostatic Traps - Stop steam flow and discharge condensate and
air accumulations into returns. These traps should be located far enough away from
condensate pump receivers so flash steam does not affect the pump’s operation.
Gate Valves - close off the flow of water from a condensate pump. In a steam
system they are normally open and are closed to isolate pumps for repair.
Gauge Glass - (aka water glass or sight glass) – a device that gives a visual
indication of the water level in a boiler. .
Gauge Pressure - is the pressure, measured in pounds per square inch gauge
(PSIG), inside the boiler as shown on a properly operating pressure gauge.
Hartford Loop - a system of piping that prevents the water from draining out of a
boiler if a leak develops in the return piping.
Heat Emitters (aka Heating Units) - convectors, cast iron radiators, wall-fin
radiation units, and similar heating devices.
Latent Heat - heat that is absorbed by the body or a thermodynamic system, during
a constant process.
Loop Riser – the vertical portion of the wet return that brings water into the
equalizer, 2" below the water line.
Low Pressure Steam - 15 PSIG or less.
Main Vent Valve (AKA Quick Vent) - a device that lets air escape quickly from
the supply main so steam can circulate and reach heating units for fast warmup. It
should be located at least 15" closer to the boiler than the last fitting of the supply
main.
54 National Oilheat Research Alliance