fans and boilers Flashcards
Which firetube boiler is built with a firebox that is not completely surrounded by water?
firebox boiler
Which boiler consists of an arrangement of drums and headers interconnected by tubes?
watertube
How many fans are used to control the draft through a balanced draft boiler?
two: one on the inlet and one on the outlet
Which boiler would be classified as a firebox boiler?
HRT
What is the minimum clearance required in front of an access panel on a gas-fired boiler?
24” regardless of whether it is insulated or not
What does the installer have to do with the boiler and piping systems before turning them over to the owner?
Inspect and test for leak-tight service
What is the cause of the most common problems encountered after start-up of steam boilers and systems?
improper cleaning and flushing
What is likely to occur if there is a heavy concentration of dissolved or suspended particles in the boiler water?
The water may foam and could cause priming
What should be done if the water in the sight glass is not clear after cleaning and flushing?
c) Repeat the cleaning procedure.
What should be done with the results of all pertinent test results during the test, start and balance phases of a system start-up?
Record the results and have the results verified.
Where is the appliance’s gross rating taken?
boiler nozzle outlet
Where is the appliance’s net rating taken?
heat emission units
What does the term pass in boiler terminology mean?
the number of times the products of combustion travel the length of the boiler
What is the main advantage of steam over hydronic systems?
speed of transmission
What is the usual maximum circulating speed of water for a low-temperature hot water heating system?
4 ft/sec
What does load tracking refer to when discussing boilers?
the ability of a boiler to respond to changes in steam or hot water demand
Which boiler has the ability to respond to sudden demands for large volumes of steam for a short period of time?
bent tube
Which boiler has the ability to handle wide variations in load over a long period of time?
water tube
Why is clean condensate considered to be ideal for feeding back into the boiler?
Condensate is essentially distilled water, so it contains no dissolved solids
How often should a pop test be done on a safety valve used on an LP steam heating boiler?
b) annually
What is the suggested method of determining whether water is flowing through a water feeder valve?
Listen with a stethoscope.
What is the most probable cause of the water level in a gauge glass fluctuating rapidly?
foaming or priming inside the boiler
What should be done if the pressure in a boiler rises higher than 20 psi during a capacity test on the safety valve?
A new valve must be installed that has sufficient capacity to pass the test.
How often should the safety valve be tested on an LP steam heating boiler?
at least once for every 30 days the boiler is operating
What is the most important thing to ensure when mounting a new glass into a water level gauge?
There should be no direct contact between the glass and the metal of the valve,
what are the three purposes of a deaerator?
removes air from feed water uses steam and screens Pre heats feed water, better efficiency. Reservoir for feed water.
If a boiler has shut down due to a low water condition, what should be done before allowing any water to be fed back into the boiler?
Allow the boiler to cool until the crown sheet of the boiler can be touched with the bare hand.
What range of pH should be maintained in the water of an LP heating boiler?
7 to 9
What is the main cause of foaming in a steam boiler?
Heavy concentrations of dissolved or suspended particles
What are the three (3) types of air required for a space in which a boiler is to be Installed?
a) combustion air b) Ventilation air c) Dilution air
What determines the type of boiler required in a system?
End use
List the measurements used to generally net rate low-pressure boilers
a) BTU b) EDR
List the measurements used to rate high-pressure boilers.
a) Boiler horsepower b) Lb of steam per hour c) MBH
What devices are installed to control the direction of flow of flue gases through the watertube boiler?
baffles
What are the three (3) most common configurations for the watertube type of package boiler?
a) A-type b) D-type c) O-type
what is a Scotch marine boiler classified as a firetube or a firebox type of boiler?
firetube
What are the two (2) names used to describe the appliances built under the ASME codes for boilers that do not use water or steam as the heat transfer medium?
a) vaporizers b) liquid heaters
List three (3) kinds of pressure found in operating fan ducts.
a) static b) velocity c) total pressure
What is a manometer used for?
A manometer is a U-shaped tube that is connected to the fan for measuring pressures
How can you remove static electricity generated by fans?
Ground the rotating element with a ground brush and cable assembly
Name the two (2) major types of fans according to flow through the impeller.
a) radial flow centrifugal b) axial flow propeller
How can control of air through fans be accomplished?
inlet louvre, outlet dampers, varying the fan speed
What is the purpose of a cold rollover of the fan rotor?
A cold rollover is used to confirm that there are no rubbing metal parts and no cracking noises experienced after a fan is overhauled.
What is natural draft?
A draft caused naturally by heat difference or pressure different, no fans
What is forced draft?
A draft created by a fan pushing air into the firebox, creating positive pressure throughout the boiler.
What is induced draft?
A draft created by a fan in between the boiler and stack or chimney, creating a low pressure before it in the boiler.
What is the purpose of nitrate testing?
To tell you how much salt is in the water, cloud instantly forms when engaged with salt. To much salt changes the heat and can lead to scale.
What is a BTU?
British thermal unit it is a way to measure temp.The amount of energy needed to raise the temperature of 1 pound of water 1°F at STP is equal to 1 BTU/s
What does the term atomizing mean?
Breaking the fuel to small amounts to mix better with air to get a better burn.
What is the maximum circulating speed of water for a low temperature hot water heating system?
4ft/sec
What is the purpose of a de-aerator?
? removes air from feed water uses steam and screens Pre heats feed water, better efficiency.
how many more times space does steam occupy?
1600
hydrostatic testing should never be done at more than what limit?
1 1/2 times boiler limit
If too little air is supplied, heat loss will occur due to incomplete combustion, this is distinguished by what?
the thick black smoke that is coming out of the stack.
If too much air is supplied, heat loss will occur because extra heat is going up the stack with the excess air, this is distinguished by what?
the white smoke that is coming out of the stack.
Hunting or surging is most pronounced in what type of fan
axial
hunting or surging is caused by what?
it is caused by the changing of air pressures as the fan cycles from high to low pressures.
complete the sentence…. Total pressure is arrived at by
adding velocity pressure to static pressure.
1 HP motor size generates about how many CFM of compressed air flow at about 90 PSI
3-4
1inch of water produces how many psig?
.036 psig
1 psig equals how many inches of water
27.7
