Basic Boiler Terminology

Front 1

A pressure gauge commonly used on hot water heating boilers. The scale is graduated in meters or feet to indicate the height of a column of water corresponding to the given pressure.

Back 1

Altitude Gauge

Front 2

A boiler that is only operated when a qualified operator is present to watch over and control the various boiler functions.

Back 2

Attended Boiler.

Front 3

A wall, barrier, or panel used to change the direction of flow of a liquid or a gas.

Back 3

Baffle

Front 4

Valves located on a line leading from the lowest part of the water side of a boiler.

Back 4

Blowoff/Blowdown Valve

Front 5

A ruptured tube or a crack which allows high-pressure steam or water to escape to the point of the boiler requiring shutdown is considered this.

Back 5

Boiler Failure

Front 6

A valve that has a hinged disk that is allowed to swing freely back and forth when pushed. If fluid passes in the flow direction, the disk is pushed open and the flow is not hindered. If the flow tries to reverse, the disk is pressed against the valve seat and the flow is not allowed to reverse.

Back 6

Check Valve

Front 7

The area of a boiler where air and fuel combine in a chain reaction to cause sustained burning.

Back 7

Combustion Chamber

Front 8

The hot gaseous products from the fire.

Back 8

Combustion Gases or Flue Gases

Front 9

When steam from a boiler is used for heating, processing, or power generation, heat energy is given up to the process and the steam ____1____. The water formed from this is called ____2_____.

Back 9

1. Condenses.

2. Condensate.

Front 10

The boiler shell together with the heads form this which contains the fluid being heated. This term is used more often for water tube boilers.

Back 10

Drum

Front 11

A boiler with the combustion chamber outside the boiler drum.

Back 11

Externally-Fired Boiler

Front 12

The water that is fed into a steam boiler to replace water which has been converted to steam and drawn off from the boiler.

Back 12

Feedwater

Front 13

A boiler consisting of a drum containing straight tubes through which the hot combustion gases from the fire travel. Water in the drum surrounds the tubes and the heat from the hot gases passes through the tube walls to the water.

Back 13

Firetube Boiler

Front 14

Any valve, gauge, regulating or controlling device, flange, or other attachment on the boiler.

Back 14

Fitting

Front 15

A device used to observe the flame in a boiler. If the flame is extinguished for any reason, it will send a signal to close the fuel supply valve and prevent explosion.

Back 15

Flame Scanner

Front 16

A fan which blows air for combustion into the furnace via the wind box.

Back 16

Forced Draft Fan

Front 17

A tube used to indicate the water level in a steam boiler.

Back 17

Gauge Glass

Front 18

This means the boiler can operate without continual control by an operator.

Back 18

Generally Supervised Boiler

Front 19

A small, hand-sized inspection, cleaning and maintenance port leading from the outside of the boiler into the pressure area of the boiler. It is covered during operation.

Back 19

Handhole

Front 20

A larger pipe which supplies to or collects from a series of smaller pipes or tubes. Also known as a manifold.

Back 20

Header

Front 21

The steel plates which close off the ends of the boiler drum. They are also referred to as end plates.

Back 21

Heads

Front 22

Consists of all parts of the boiler through which heat from the burning fuel is transferred to the water side of the boiler. It includes all parts of the boiler plates and tubes which have water or steam on one side and are swept by fire or hot combustion gases on the other side.

Back 22

Heating Surface

Front 23

A boiler that operates at pressures above 103 kPa.

Back 23

High Pressure Steam Boiler or Power Boiler

Front 24

A firetube boiler usually supported in a brick combustion chamber. The hot gases from combustion sweep along the underside of the shell then return through the fire tubes to the chimney connection.

Back 24

Horizontal Return Tubular Boiler (HRT)

Front 25

A closed vessel completely filled with water to which heat is added to raise the temperature of the water. No steam is generated.

Back 25

Hot Water Boiler

Front 26

A fan used to draw combustion gases out of the boiler and blow them up the chimney.

Back 26

Induced Draft Fan

Front 27

A boiler that has the combustion chamber located within the shell of the boiler, or the furnace is surrounded by water tubes.

Back 27

Internally-Fired Boiler

Front 28

Controls that have their set point adjusted higher than the boiler operating controls set point. If the normal operating controls fail to limit the rise in temp or pressure, these controls will shut off the fuel supply to the boiler.

Back 28

Limit Controls

Front 29

The lowest water level at which the boiler can be safely operated without damaging or overheating any part of the boiler.

Back 29

Lowest Permissible Water Level

Front 30

A boiler that operates at a pressure not above 103 kPa.

Back 30

Low-Pressure Steam Boiler

Front 31

A safety device which cuts off the fuel supply to the burner if the boiler water level drops below a safe level.

Back 31

Low-Water Fuel Cutoff

Front 32

An opening or hatch through which a person may enter into the shell/drum of a boiler.

Back 32

Manhole

Front 33

The controls that operate the combustion equipment on a boiler. Changes in steam demand from the boiler require a corresponding change in the firing rate of the boiler.

Back 33

Operating Controls

Front 34

A boiler supplied by the manufacturer completely equipped and mounted on it's own base.

Back 34

Packaged Boiler

Front 35

The protective layer of material that is applied to various parts of the boiler to withstand high temperatures and abrasion.

Back 35

Refractory.

Front 36

A safety device that acts like a safety valve to protect against excessive pressure buildup in a system. However, this disk shatters when it's max. pressure is reached and must be replaced each time it activates.

Back 36

Rupture Disk

Front 37

This fitting prevents the pressure within a steam boiler from exceeding safe limits. It will pop open when the pressure inside the boiler reaches a set point, until it is reduced to another preset pressure and then it will close.

Back 37

Safety Valve

Front 38

The brickwork used to support a boiler and surround the combustion chamber.

Back 38

Setting

Front 39

A device used to blow accumulated soot off tubes and heating surfaces in a boiler.

Back 39

Soot Blower

Front 40

The hollow duct through which combustion gases are elevated for discharge to the atmosphere.

Back 40

Stack

Front 41

A closed container partially filled with water that is evaporated to steam under pressure by the application of heat.

Back 41

Steam Boiler

Front 42

A fitting attached to a boiler to indicate the internal pressure of the boiler.

Back 42

Steam Gauge

Front 43

The space above the water line in a boiler where the boiling water and steam can separate from each other.

Back 43

Steam Space

Front 44

The main valve on the steam line leaving the boiler.

Back 44

Steam Stop Valve

Front 45

A protective device used to prevent steam from entering the internal works of a steam gauge.

Back 45

Syphon

Front 46

Small valves installed directly on the water column that allow the operator an alternative method of checking the water level in the gauge glass.

Back 46

Try Cocks

Front 47

The duct used to convey the spent combustion gases from the boiler to the stack or chimney. Also known as the flue vent and breeching.

Back 47

Uptake

Front 48

A smaller sized fire tube boiler with vertical fire tubes.

Back 48

Vertical Tubular Boiler

Front 49

A chamber attached at top and bottom to a steam boiler. A gauge glass is normally attached to this to give a visual indication of the water level.

Back 49

Water Column

Front 50

The actual level of water in a boiler. It is the point at which water and steam separate.

Back 50

Water Line

Front 51

The portion of the boiler normally filled with water.

Back 51

Water Space

Front 52

A water-filled section that extends from the shell that surrounds the firebox of some types of boilers. Most locomotive boilers are equipped with these.

Back 52

Waterlegs

Front 53

A boiler consisting of drums and headers that circulate water through tubes which are heated by fire and the products of combustion. The heat from the fire is transmitted through the tubes to the water.

Back 53

Watertube Boiler

Front 54

The box surrounding the burner damper on a boiler. The fan blows combustion air into this box and the damper regulates and directs the air into the burners.

Back 54

Windbox