MCs from Boiler Operator Exam Book

At 0 PSIG, how many BTU are necessary to change 1 lb of water at 212 degrees Fahrenheit into 1 lb of steam?

c. 970

Radiation is

a form of heat transfer by waves

Steam at 100 psi and 400 F is

Superheated

What is sensible heat?

Heat that can be sensed or measured with a thermometer

What is required to raise the temperature of 1 lb of water from 32 to 212 ºF

180 BTU

Increasing the pressure has what effect on the boiling point of water

Temperature will be raised

Heat absorbed by water when it changes from liquid to steam at the boiling point is called

latent heat

Heat can be transferred in how many ways

three

A boiler horsepower is defined as

Evaporation of 34.5 pounds of water at 212 ºF per hour

A boiler's steam pressure gauge reads 150. What is the absolute pressure?

164.7 psia

What does 212 degrees F equal on the Celsius scale?

100

One boiler horsepower is equal to how many BTU

33,472

A BTU is

The amount of heat needed to raise the temperature of 1 pound of water 1˚F

Hydronic heat is

Hot water heat

Superheated steam is

reheated steam

2,545 Btuh represents

1 horsepower-hour

A throttling calorimeter is used to measure the quality of

Saturated steam

The amount of heat in one pound of saturated steam is approximately equal to?

1,150 Btu

A boiler operating at 100 PSI has a dry saturated steam temperature of 338 degrees F. What is the boilers water temperature?

338ºF

A dry pipe is used to

separate moisture from steam as it leaves the drum

The purpose of a stay bolt is to

Strengthen and support flat plates of a fire tube boiler

The boiler vent is located on the

highest part of the steam drum

The purpose of the hole in the end of the staybolt is to

Indicate that a staybolt is cracked or broken

A fusible plug melts at

450 F

As the firing rate increases in a boiler equipped with a convection superheater the steam temperature

increases

when boilers are connected to a common header, it is required that an ample free blowing drain be provided between the stop valves if either or both boilers have

Manholes

It is permissible to have only one bottom blow down valve on a boiler when the

MAWP does not exceed 100 psi

When the boiler pressure exceeds _____ psi it is required that extra heavy pipe be used on the blowoff system

125

Baffles are placed between the tubes of the boiler for the purpose of

directing the travel of flue gases

A boiler has a steaming capacity of 35,500 lb of steam per hour. The evaporation rate is 10 lb/ft^2 of heating surface per hour. What is the horsepower rating of this boiler?

1,000

Boiler tube sizes are specified by

outside diameter

The maximum size of boiler blowdown lines, valves, and fittings shall not exceed?

2.5 inches

The purpose of an expansion tank in a hot water heating system is to provide expansion of

Water

Heavy accumulation of soot in a boiler will result in

loss of boiler efficiency

How are the tubes secured in a fire tube boiler

Rolled and beaded over

A tube in a fire-tube boiler is surrounded by

Water

Atmospheric pressure is considered to be

14.7 psia

In a water tube boiler

flue gases surround tubes

Diagonal stays are found in

Fire tube boilers

Handholes and manholes are oval

for removal from a pressure vessel

To check the water level in the gauge glass of a steam boiler

Use the tricocks

The vent valve

removes air during warm up AND prevents a vaccuum from forming during cooldown

A high pressure boiler has its safety valve set above

15 psi

What is an advantage of fire tube boilers over water tube boilers

Low initial cost

Water walls are found

in water tube boiler furnaces

The best time to bottom blow down a boiler is at

Low load under full pressure

A telltale hold is found in a

Staybolt

A 2-inch boiler tube has a wall thickness of 3/16 inch. What is its inside diameter (ID)?

1 5/8 inches

At what temperature does steel start to lose its strength

700 ºF

A hot water heating system is about to be started. How full of water should the expansion tank gauge glass be

1/3

What is the relationship between longitudinal stress and circumferential stress

Longitudinal stress is twice circumferential stress.

A therm is equal to how many BTU

100,000 BTU

The factor of evaporation is

heat added to the boiler divided by 970.3

The purpose of bottom blow down is to

Remove sludge and sediment

Damage by spalling refers to the

refractory

Superheaters raise the temperature of

steam

The steam space is

The area above the operating water level

the heating surface of a boiler is the area

exposed to the flame and flue gases

The purpose of a superheater is to

heat steam above its saturation temperature

What is the formula for the factor of evaporation

H-b/970.3 Btu

What can cause superheater tube to overheat

Dirty tube

a boiler has a steaming capacity of 34,500 lb of steam/hr. the evaporation rate is 10 lb/ft^2 of heating surface per hour. what is the boiler heating surface?

3450

How many square feet of heating surface does a 3 inch fire tube 20 ft long with a 3/16 inch wall have

13.7

In a high temperature hot water boiler, what would cause a tube to overheat

Poor circulation (plugged tube)

A downcomer is found

In a water tube boiler

Extreme firebox temperature changes cause

Spalling

The low water cut off

shuts off the burner when the boiler is low on water

Steam coming from the bottom tricock would indicate

Low water level

What valve has the most resistance to flow

Globe

When checking the water level of a boiler

blow down the gauge glass and water column

a siphon or pigtail is used to protect a steam pressure gauge

from steam temperature

The feed water regulator is located

At the normal operating water level

An automatic feedwater regulator

ensures the proper water level in the boiler

To test the low water cutoff

the burner must be firing

The purpose of testing a safety valve by hand is to

make sure the valve can lift

The automatic control that protects a boiler from being dry fired is the

low water cutoff

To check the water level in the gauge glass of a steam boiler

blow down the gauge glass and water column

On a steam boiler, testing the operation of the safety valve by hand with the boiler under pressure should be done

monthly

What valve has the least resistance to flow

Gate

The gauge glass shows full while the middle tricock shows steam. When blow down, the gauge glass refills. What is the probable cause?

The top gauge glass connection of blocked

The purpose of a bowl at the bottom of the water column is to

serve as a sediment chamber

When checking the safety valve with hand-lifting gear, the pressure should be no lower than _____ % of the safety valve pressure

75

If valves are located between the boiler and water column, they must be?

locked or sealed open

When a hydrostatic test is put on a boiler, each safety valve should be

Held to its seat by means of a testing clamp

After installing a new gauge glass,the proper procedure for returning the glass to service is

Open the drain and crack the top valve (allow the steam to warm the glass so the hot water doesn't shock the material and break it)

The steam pressure gauge is graduated in

pounds per square inch

One of the purposes of the water column is to

dampen the oscillation of the water in the gauge glass

The gauge glass should be blown down

daily

The flame failure control is tested by

securing the fuel supply to the burner

Which control operates due to changes in temperatures

Aquastat

The pressure sensitive device attached to the fan housing of a fully automatic burner starts operating when there is

Fan failure

If the pressuretrol starts the burner and ignition failed to take place, the control that protects the boiler is the

flame failure cutoff

Pressure sensitive device attached to the fan housing that operates when there is fan failure is called the

Vaporstat

Draft is measured in

inches of water column

What is a pyrometer used to measure

Temperature

The main stop valve is located on the

steam line

OS&Y stands for

Outside screw and yoke

An interlock control is a

Device that prevents attempts to fire unless safe

Trial for ignition refers to the

flame scanner detecting the pilot flame

More than one safety valve is required on boilers that have over

500 ft^2 of heating surface