Steam and Hot Water Boiler Controls 080307c

Question 1

What is the maximum allowable pressure for a low pressure steam boiler?

Answer 1

15 psig

Question 2

What is the function of the differential pressure switch (DOPS)?

Answer 2

Cuts off the fuel supply when the steam pressure reaches an operating set point

The DOPS is a pressure sensing switch

Question 3

What is the function of the high limit pressure switch in a steam boiler?

Answer 3

Cuts off fuel supply to prevent steam pressure from exceeding the maximum allowable pressure (15 psig)

Question 4

The loop of a pigtail should be set at ___° to the face of any pressure controls with mercury switches in them

Answer 4

90

Question 5

A flow switch is required on what kind of boiler?

Answer 5

Low mass over 400MBH

Question 6

A low water cut off is required on what kind of boiler?

Answer 6

High mass over 400MBH

Question 7

Many different types of sensing elements can be found on aquastats, but most common one is what?

Answer 7

Liquid bulb with capillary tube

Question 8

An alternate method of installation of a sensing bulb is what?

Answer 8

Immersion well (thermal well)

Question 9

A high limit switch is what kind of switch?

Answer 9

Single pole single throw break on temp rise

Question 10

What is the function of a safety limit control on a hot water boiler?

Answer 10

Prevent water temperature from exceeding the maximum allowable temperature (250°F)

Question 11

What is the maximum allowable temperature in a hot water boiler?

Answer 11

121°C (250°F)

Question 12

Once a limit control has closed the gas valve, the control will not allow the boiler to fire until what happens?

Answer 12

The control has been reset manually

Question 13

What is considered the final form of boiler protection?

Answer 13

Safety relief valve

Question 14

What is the function of the safety relief valve on a steam boiler system?

Answer 14

It safeguards the boiler from over pressuring

Question 15

What 2 pressure controls must a steam boiler have?

Answer 15

Differential operating pressure switch (DOPS)

High limit pressure switch

Question 16

What 2 controls must a hot water boiler have?

Answer 16

Operating temperature switch

High limit temperature control switch

Question 17

Boiler maintenance may be as little as how often?

Answer 17

Yearly

Question 18

If a float chamber type control seems stuck in the up position after us has been drained, what may be the solution?

Answer 18

Tap on it

Question 19

High oxygen content in a boiler system may cause what?

Answer 19

Will corrode steel components in the system and may result in boiler failure

Question 20

How much slope should be on a horizontal vent connector?

Answer 20

Not less than 1/4” per foot

Question 21

What is the sequence of operations for a an electrical ladder diagram?

Answer 21

Power - Switch - Load

Question 22

Where is a reduced principal backflow preventer placed on a boiler system?

Answer 22

On the boiler feed water line immediately upstream of the boiler feed water valve

Question 23

Operating controls have what kind of differential?

Answer 23

Adjustable

Question 24

Safety controls have what kind of differential?

Answer 24

Fixed

Question 25

What is the reason for installing crosses in the piping harness controls?

Answer 25

Cleaning

Question 26

Steam and hot water boilers require what kind of safety relief?

Answer 26

Pressure (not temp on either)

Question 27

What is required on high mass boilers over 400,000 BTU?

Answer 27

Low water but off