P99 LOW PRESSURE BOILERS
EXAM REVISION SUMMARY
A Firetube Boiler
A boiler in which heat and gases of combustion pass
through tubes surrounded by water.
A Watertube Boiler
A boiler in which water passes through tubes surrounded
by gases of combustion.
Baffles
Used in boilers to direct the gases of combustion over the
boiler heating surface.
Sensible Heat
the heat we can feel and measure with a thermometer
Heat Exchanger
used to transfer heat from one substance to another
without allowing the materials to mix.
Air Mixes with fuel and burns in the:
Combustion Chamber
Combustion that occurs when fuel is burned using
only the theoretical amount of air:
Perfect Combustion
Provides the air necessary for combustion
The Draft System
A Cast Iron Boiler
Does NOT use tubes.
To increase efficiency of a cast iron boiler:
the heating surface is increased
The Four systems necessary to operate a boiler are:
,Feedwater, Fuel, Draft, Condensate
The pressure caused by the weight of air surrounding
the earth:
Atmospheric Pressure
Cast iron boilers have sections that can be assembled
on site to produce the boiler capacity required.
The amount of energy needed to raise the temperature
of 1 pound of water 1 degree F.
One BTU
A component directly attached to the boiler that is
required for the operation of the boiler:
Boiler Fitting
The nonflammable material used to insulate the outer
surface of the boiler from heat is the:
Refractory
The most important valve on a boiler
Safety Valve
The MAWP on a low pressure boiler is:
15 PSI
Total Force on a safety valve is equal to
Area times Pressure
The ASME Code states that the boilers with over 500
square feet of heating surface must have:
two or more safety valves
The range of the pressure gauge should be:
1.5 to 2 times the MAWP of the boiler
The Steam pressure gauge on a boiler is calibrated to
read:
Pounds per square inch
Steam is prevented from entering the Bourdon tube of
the pressure gauge by a:
, Siphon
A gauge that can read either vacuum or pressure
Compound Pressure Gauge
vacuum is pressure BELOW atmospheric pressure
Safety valves are designed to pop open and stay open
until there is a:
2 to 4 PSI drop in pressure
Blowback is the Drop In Pressure in the boiler after
the safety valve is opened.
Impurities that build up on the surface of the water in
the boiler prevent:
steam from breaking through the surface of the water
The operating range of a boiler is controlled by:
pressure control
The modulating pressure control:
regulates the firing rate between high and low fire of the
burner.
The level of water in the gauge glass:
indicates the water level in the boiler
Provides access inside the water side of the boiler for
inspaection, sight, or cleaning:
Handhole
According to ASME, a try lever test on safety valves
should be performed every:
30 days that the boiler is in operation
The capacity of the safety valve is measure by the
amount of steam that can be discharged per HOUR.
When a safety valve opens and closes rapidly:
Chattering
After the total force of the steam has lifted the safety
valve off its seat, steam enters the:
EXAM REVISION SUMMARY
A Firetube Boiler
A boiler in which heat and gases of combustion pass
through tubes surrounded by water.
A Watertube Boiler
A boiler in which water passes through tubes surrounded
by gases of combustion.
Baffles
Used in boilers to direct the gases of combustion over the
boiler heating surface.
Sensible Heat
the heat we can feel and measure with a thermometer
Heat Exchanger
used to transfer heat from one substance to another
without allowing the materials to mix.
Air Mixes with fuel and burns in the:
Combustion Chamber
Combustion that occurs when fuel is burned using
only the theoretical amount of air:
Perfect Combustion
Provides the air necessary for combustion
The Draft System
A Cast Iron Boiler
Does NOT use tubes.
To increase efficiency of a cast iron boiler:
the heating surface is increased
The Four systems necessary to operate a boiler are:
,Feedwater, Fuel, Draft, Condensate
The pressure caused by the weight of air surrounding
the earth:
Atmospheric Pressure
Cast iron boilers have sections that can be assembled
on site to produce the boiler capacity required.
The amount of energy needed to raise the temperature
of 1 pound of water 1 degree F.
One BTU
A component directly attached to the boiler that is
required for the operation of the boiler:
Boiler Fitting
The nonflammable material used to insulate the outer
surface of the boiler from heat is the:
Refractory
The most important valve on a boiler
Safety Valve
The MAWP on a low pressure boiler is:
15 PSI
Total Force on a safety valve is equal to
Area times Pressure
The ASME Code states that the boilers with over 500
square feet of heating surface must have:
two or more safety valves
The range of the pressure gauge should be:
1.5 to 2 times the MAWP of the boiler
The Steam pressure gauge on a boiler is calibrated to
read:
Pounds per square inch
Steam is prevented from entering the Bourdon tube of
the pressure gauge by a:
, Siphon
A gauge that can read either vacuum or pressure
Compound Pressure Gauge
vacuum is pressure BELOW atmospheric pressure
Safety valves are designed to pop open and stay open
until there is a:
2 to 4 PSI drop in pressure
Blowback is the Drop In Pressure in the boiler after
the safety valve is opened.
Impurities that build up on the surface of the water in
the boiler prevent:
steam from breaking through the surface of the water
The operating range of a boiler is controlled by:
pressure control
The modulating pressure control:
regulates the firing rate between high and low fire of the
burner.
The level of water in the gauge glass:
indicates the water level in the boiler
Provides access inside the water side of the boiler for
inspaection, sight, or cleaning:
Handhole
According to ASME, a try lever test on safety valves
should be performed every:
30 days that the boiler is in operation
The capacity of the safety valve is measure by the
amount of steam that can be discharged per HOUR.
When a safety valve opens and closes rapidly:
Chattering
After the total force of the steam has lifted the safety
valve off its seat, steam enters the:
