chapter 7

Question 1

The LWFCO on a hot water heating boiler

a. Can be a combination control
b. Must be installed so that the water does not fall below the top of the bottom nut of the gauge glass
c. May be installed at any point above the lowest permissible water level
d. Is not required in Manitoba

Answer 1

c

Question 2

To maintain the water level in a steam boiler, it is always preferable to prioritize the return of _____________ to the boiler

a. makeup water
b. condensate
c. natural gas
d. steam

Answer 2

b

Question 3

On a hot water heating boiler, makeup water to the boiler is controlled by the:

a. secondary supply valve
b. combination low water fuel cutoff
c. makeup water PRV
d. single separate low water fuel cutoff

Answer 3

c

Question 4

The low water cutoff control must be attached to

a. the boiler’s steam space and water space
b. the boiler’s condensate tank
c. Incorrect Response
the boiler’s water column
d. the boiler’s gauge glass connections

Answer 4

a

Question 5

If a steam boiler is fitted with a second source of water supply right on the boiler, the second source is controlled by the combination low water fuel cut-off

True
False

Answer 5

true

Question 6

When a boiler is fitted with a secondary source of water supply on the boiler itself, the secondary supply is usually:

a. city water
b. feedwater
c. a solenoid valve
d. condensate

Answer 6

a

Question 7

All steam boilers have a second source of water supply installed on the boiler itself

True
False

Answer 7

false

Question 8

A condensate receiver tank fitted with an internally-mounted makeup water feeder is the preferable method of feeding makeup water to the tank because:

a. the internal float is protected from water hammer
b. the internally-mounted style of float control provides larger capacity
c. internally-mounted makeup water feeder is not the preferable method of feeding makeup water to a condensate receiver tank
d. violent fluctuations in condensate return will affect the float control

Answer 8

c

Question 9

The two kinds of water supplied to a low pressure steam boiler in a small heating application

a. City water and raw water
b. Make-up water and city water
c. Condensate and steam water
d. condensate and makeup water

Answer 9

d

Question 10

The single separate low water cut off must be attached to the gauge glass connections

True
False

Answer 10

False

Question 11

Make-up water for the heating system usually comes from the:

A.Deaerator
B.Returning condensate
C.Boiler feedwater
D.City water supply
E.Boiler feedwater pump

Answer 11

d

Question 12

The float in the low water fuel cut-off will activate:

A.A globe valve
B.A solenoid valve
C.An electrical switch
D.A gate valve
E.An electrical relay

Answer 12

c

Question 13

At normal boiler steaming rates, a condensate receiver tank should contain a sufficient volume of water equivalent to the water evaporated by the boiler for a maximum period of _____ minutes.

A.30
B.15
C.60
D.20
E.45

Answer 13

a

Question 14

A second source of feedwater may be controlled by the:

A.Automatic blowdown device
B.Boiler operating control
C.Feedwater control switch
D.Low water fuel cut-off device
E.Boiler drum level control

Answer 14

d

Question 15

The float operated low water fuel cut-off works on the principle of:

A.Drum level variation
B.Temperature change
C.Steam density
D.Buoyancy
E.Differential pressure

Answer 15

d

Question 16

The low water level fuel cut-off will shut off the fuel to the heating boiler when the water level drops below:

A.25 mm (1 in.) above the bottom of the gauge glass
B.The lowest visible part of the gauge glass
C.The lowest permissible water level
D.One half of the gauge glass
E.50 mm (2 in.) above the bottom of the gauge glass

Answer 16

b

Question 17

The low water level fuel cut-off will shut off the fuel to the heating boiler when the water level drops below:

A.25 mm (1 in.) above the bottom of the gauge glass
B.The lowest visible part of the gauge glass
C.The lowest permissible water level
D.One half of the gauge glass
E.50 mm (2 in.) above the bottom of the gauge glass

Answer 17

C

Question 18

The low water fuel cut-off float is commonly used to operate both the Low water fuel cut-off switch and the:

A.High steam pressure switch
B.Low feedwater temperature alarm
C.Low fuel gas pressure switch
D.Feedwater control switch
E.Low steam pressure alarm

Answer 18

d

Question 19

In a building heating system the condensate in the condensate receiver tank comes from the:

A.Heating system
B.Boiler feedwater
C.Make-up water supply
D.Economizer
E.Deaerator

Answer 19

a

Question 20

Low water fuel cut-off devices require regular attention, the following intervals are recommended:
1. Once per shift
2. Daily
3. Weekly
4. Monthly
5. No attention is required

A.3, 4, 5
B.2, 3, 5
C.1, 2, 4
D.2, 3, 4
E.1, 2, 3

Answer 20

d

Question 21

the ________ operated low water fuel cutoff uses buoyancy to operate the switch

a. float
b. electrode
c. bi-metal
d. thermal

Answer 21

a

Question 22

the type of low water fules cut off that uses the cunductivity of the water to operate is the __________type

a. float
b. thermal
c. three wire
d. electrode probe

Answer 22

d

Question 23

a low water fuel cut off combination pump control will ____________ water level reaches a low level, but still above the lowest permissible level

a. shut down the boiler
b. start the feedwater pump
c. close the fuel valve
d. open the safety valve

Answer 23

b

Question 24

low water levels can develop in hot water boilers due to human error

true
false

Answer 24

true

Question 25

on a steam boiler, test the low water fuel cut off while the boiler is operating by

a. increasing the steam pressure
b. blowing down the boiler
c. opening the drain valve on the float chamber
d. doing a pop test

Answer 25

c

Question 26

a three wire (double pole) switch on a lwfco will shut off the fuel and sound an alarm

true
false

Answer 26

true