Technical Glossary

If you are looking for a bit more information and need a technical reference, AllPoints has that for you. Click on a letter to take you to the list of terms and technical information starting with that letter.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Glossary: A

AC (Alternating Current)
An electric current that reverses directions at regularly occurring intervals.
AMP (Ampere)

A unit of flow of electrical current.

OHM'S LAW:

OHM'S LAW OHM'S LAW OHM'S LAW For three phase A.C. circuits OHM'S LAW
Armature
The rotating part of a motor or the moving part of a contactor or relay.

Glossary: B

Bimetal
Two dissimilar types of metal fastened together, when heated they bend which can open or close a circuit.
Bleed Gas
A small flow of gas that assists a diaphragm of a bleed gas valve to operate.
Boiler Horsepower
One boiler horsepower equals 33,475 BTU/HR
Booster

An electric, gas or steam hot water booster for a commercial dishwasher that will supply 180 degrees F minimum rinse water. Formula to size an electric booster.

G.P.H. / 10 = KW based on 40 degrees F temperature rise.

BTU (British Thermal Unit)
The heat required to raise the temperature of one pound of water by one degree Fahrenheit. One BTU per minute = 17.58 watts.
Bypass
A small passageway machined in a valve to allow gas or water to bypass around a closed valve.

Glossary: C

Capacitor
An electrical device to store electrical energy, block the flow of dc current, and to act as a conductor of AC current.
Capillary
A hollow tube used to allow a liquid or gas to flow in a temperature control.
Centigrade Temperature

Metric system scale, 0 degrees being the freezing point and 100 degrees being the boiling point of water. Degrees centigrade =.555 (degrees Fahrenheit -32)

Centigrade Fahrenheit Centigrade Fahrenheit Centigrade Fahrenheit Centigrade Fahrenheit Centigrade Fahrenheit
-50 -58 50 122 150 302 250 482 350 662
-45 -49 55 131 155 311 255 491 355 671
-40 -40 60 140 160 320 260 500 360 680
-35 -31 65 149 165 329 265 509 365 689
-30 -22 70 158 170 338 270 518 370 698
-25 -13 75 167 175 347 275 527 375 707
-20 -4 80 176 180 356 280 536 380 716
-15 5 85 185 185 365 285 545 390 734
-10 14 90 194 190 374 290 554 390 734
-5 23 95 203 195 383 295 563 395 743
0 32 100 212 200 392 300 572 400 752
5 41 105 221 205 401 305 581 405 761
10 50 110 230 210 410 310 590 410 770
15 59 115 239 215 419 315 599 415 779
20 68 120 248 220 428 320 608 420 788
25 77 125 257 225 437 325 617 425 797
30 86 130 266 230 446 330 626 430 806
35 95 135 275 235 455 335 635 435 815
40 104 140 284 240 464 340 644 440 824
45 113 145 293 245 473 345 653 445 833
CFM (Cubic Feet per Minute)
Measurement of air volume by an air handling device.
Combination Gas Valve
A control valve that consists of some or all of the following: manual valve, automatic safety shutoff, main actuator valve, pressure regulator and pilot adjuster.
Contactor
An electromagnetic actuated relay used to close an electrical circuit
Continuity
A continuous path for the flow of electricity.
Current
The flow of electricity, measured in amperes.

Glossary: D

D.C.(Direct Current)
A steady flow of electrical current in one direction only.
Diastat
Part of a thermostat consisting of a sensing bulb, hollow capillary tube and a bellows. This sealed system is filled with a fluid which expands when heated to actuate electrical contacts.
Differential
The difference between the on and off temperatures of an operating thermostat.
Direct Spark Ignition
Two high voltage electrodes create a continuous spark to ignite a main burner.
Disposer

Master disposer replacement work sheet.

Master disposer replacement work sheet
D.P. (Double Pole)
A switch device that opens or closes connections in two conductors of the same circuit. D.P. (Double Pole)
D.P.D.T (Double Pole, Double Throw)
A switch that opens or closes connections alternately in two conductors of the same circuit. D.P.D.T (Double Pole, Double Throw)
D.P.S.T. (Double Pole, Single Throw)
A switch that opens or closes connections at one position in two conductors of the same circuit. D.P.S.T. (Double Pole, Single Throw)

Glossary: E

ECO
Energy Cut-Off Device

Glossary: F

Fahrenheit
Temperature scale, 32°F being the freezing point and 212 °F being the boiling point of water.

Degrees Fahrenheit = (1.8 x °Centigrade) + 32

Centigrade Fahrenheit Centigrade Fahrenheit Centigrade Fahrenheit Centigrade Fahrenheit Centigrade Fahrenheit
-50 -58 50 122 150 302 250 482 350 662
-45 -49 55 131 155 311 255 491 355 671
-40 -40 60 140 160 320 260 500 360 680
-35 -31 65 149 165 329 265 509 365 689
-30 -22 70 158 170 338 270 518 370 698
-25 -13 75 167 175 347 275 527 375 707
-20 -4 80 176 180 356 280 536 380 716
-15 5 85 185 185 365 285 545 390 734
-10 14 90 194 190 374 290 554 390 734
-5 23 95 203 195 383 295 563 395 743
0 32 100 212 200 392 300 572 400 752
5 41 105 221 205 401 305 581 405 761
10 50 110 230 210 410 310 590 410 770
15 59 115 239 215 419 315 599 415 779
20 68 120 248 220 428 320 608 420 788
25 77 125 257 225 437 325 617 425 797
30 86 130 266 230 446 330 626 430 806
35 95 135 275 235 455 335 635 435 815
40 104 140 284 240 464 340 644 440 824
45 113 145 293 245 473 345 653 445 833
Field Coil
A coil of insulated wire wrapped around an iron core. When electric current flows through the coil, a magnetic field is produced. Used in motors in conjunction with an armature.
Gas Orifice Capacity Chart (BTU Ratings)
Please click here for chart.

Glossary: G

Glow Coil
A coil of fine wire which when heated by an electrical current glows and is used to light a pilot flame.
GPH (Gallons Per Hour)
The measurement of the flow of a volume of liquid. To convert GPH to GPM divide by 60.
GPM
Gallons Per Minute

Glossary: H

Hot Surface Ignition
A resistive element is used to heat and ignite a gas burner.
Hp (horsepower)
One horsepower = 2544 B.T.U. per HR.
One horsepower = 745.2 watts
Horsepower = KW
3 5
5 5
7.5 7
10 9.5
15 12.5
20 15.5
25 18
HZ (Hertz)
Frequency of ac power in cycles per second. Usually 60 HZ in USA and 50 HZ overseas.

Glossary: I

ID
Internal Diameter
Inches of Water Column
A measurement of gas pressure, one inch of water column equals 0.036 psi. 28 inches of water column equals 1 psi.
Infrared Burner
Heat is produced by a glowing burner surface which radiates infrared energy.
Intermittent Pilot Ignition
Pilot flame ignites only when main gas burner is to be ignited.
IPS
Iron Pipe Size

Glossary: J

Jet Burner
A burner in which gas and air mixtures combine in air above the burner ports to burn.

Glossary: K

KPA (Kilopascal)
Metric pressure measurement.
kW (Kilowatt)
One kW equals 1,000 watts.
kWh (Kilowatt Hour)
The amount of energy one kilowatt produces in one hour. One kilowatt hour = 3412 Btu Per hour.

Glossary: L

Line Voltage
The voltage level of the main power supply.
Load
Electrical power consumed by components of an electrical circuit.
LPG (Liquefied Petroleum Gas)
Referred to as propane.

Glossary: M

Manometer
Instrument for the measure of gas pressure in inches of water column.
Milliamp
1 /1000 of an ampere.
Millivolt
1 /1000 of a volt
Mini-Pilot
A thermocouple and pilot combines in one device.

Glossary: N

Natural Gas
Gas extracted from the earth.
N.C.
Normally Closed Normally Closed A switch or other device which is in the closed position when not energized or activated.
N.O.
Normally Open Normally Open A switch or other device which is in the open position when not energized or activated.

Glossary: O

OD
Outside Diameter
OHM
The resistance which will allow one ampere of current to flow when the voltage is one Volt.
Ohm's Law
Equations of relationship of voltage, current, and resistance. Ohm's Law Ohm's Law Ohm's Law

Equations of Relationships of Voltage, Current and Resistance

Common Equations Derived from OHM'S LAW:

REMEMBER:

  • I = AMPS: Measures Current
  • E = VOLTS: Measures Electrical Force
  • R = OHMS: Measures Resistance to Electric Current
  • W = WATTS: Electric Power or Heat Energy
Ohm's Law

If elements are designed for 3-PHASE DELTA connection, wattage output may be reduced to 1/3 by reconnecting to 3-PHASE WYE

FOR CURRENT IN 3-PHASE CIRCUITS

Ohm's Law Calculation Examples

Ohm's Law Ohm's Law Calculation Examples Ohm's Law
Open Circuit
An electrical circuit through which a current can not flow because of an open switch or other break in the wiring.

Glossary: P

Parallel Circuit
An electrical circuit in which more than one path is provided for the current flow.
Pilot Safety Valve
A valve of which closes when pilot flame does not exist, valve automatically stops the flow of gas to the pilot and main burners.
Pipe Sizes
Dimensions of standard pipe.
Nominal Pipe Size Threads per Inch Inside Diameter Inches Outside Diameter Inches
1/8" 27 .269 .405
1/4" 18 .364 .540
3/8" 18 .493 .675
1/2" 14 .622 .840
3/4" 14 .824 1.050
1" 11-1/2 1.049 1.315
1-1/4" 11-1/2 1.380 1.660
1-1/2" 11-1/2 1.610 1.900
2" 11-1/2 2.067 2.375
2-1/2" 8 2.469 2.875
Pressure Drop
The decrease in gas pressure as gas passes through a control or piping.
Primary Side of Transformer
The high voltage side of a step-down transformer.
PRV (Pressure Reducing Valve)
A mechanical valve that reduces the incoming pressure of air, water or steam to a Lower set pressure.
PSI
Pounds Per Square Inch
PSIG
Pounds Per Square Inch Gauge

Glossary: R

Relay
An electromagnet device used in a control circuit to provide electric current to a valve or switch. Referred to as a start relay when used for a motor.
Resistor
A device to limit the current flow in a circuit.
Rheostat
A type of resistor where the resistance can be adjusted to various levels.

Glossary: S

Safety Pilot Valve
See pilot safety valve.
Secondary Transformer Winding
Low voltage side of a step down transformer.
Series Circuit
An electrical circuit in which only one continuous path is provided for the flow of current, so that the current flows through all components in the circuit.
Solenoid
A wire wound coil that creates a magnetic field when energized.
Solenoid Valve
A valve operated by a solenoid coil.
Solid-state
Semiconductor type switching device with no moving parts to control an electrical circuit.
S.P. (Single Pole)
S.P. (Single Pole) A switch device that opens or closes connections in a single conductor.
S.P.D.T.
Single Pole, Double Throw Single Pole, Double Throw A switch that opens or closes connections at one position in a circuit.
S.P.S.T
Single Pole, Single ThrowVoltA switch that opens or closes connections at one position in a circuit.
Standing Pilot
Pilot flame remains lit whether main burner is off or on.
Steam Temperature/Pressure Table
Gauge Pressure P.S.I.G. Temperature Fahrenheit
0 212
2 218.5
4 224.4
6 229.8
8 234.6
10 239
15 249.7
25 266.8
30 274
40 286.7
50 297.7

Glossary: T

Therm
100,000 BTU's
Thermal Overload Protector
A device which trips an internal switch to interrupt electrical current to protect against an over current condition.
Thermocouple
A device containing two different metals which produces a small amount of DC voltage when heated. Operates a pilot safety valve.
Thermopile
A group of thermocouples contained in one unit, when heated by a pilot flame millivolts are generated to energize a pilot safety valve or power a millivolt operated control.
Thermostat
An automatic device actuated by temperature changes to control a preset operating temperature.
Transformer
A device for changing one voltage to another voltage.
Tubing Sizes
Type K and L Copper Water Tubing
Nominal Size Inches Actual Outside Diameter Inches
1/4 3/8
3/8 1/2
1/2 5/8
3/4 7/8
1 1-1/8
1-1/4 1-3/8
1-1/2 1-5/8
2 2-1/8
Two-Stage Pilot
A pilot ignition system that uses a small standing pilot flame to light a larger pilot.

Glossary: V

Vac
Volts Of Alternating Current
Vacuum
A pressure lower than atmospheric pressure.
VDC
Volts Of Direct Current
Venturi
A piece of pipe that attaches to a burner. Because it narrows down then flares out it Increases gas velocity to create a negative pressure for combustion.
Volt
One volt will produce a flow of one ampere through a one OHM resistance. OHM'S LAW VOLTS = AMPERAGE x OHMS
Voltage
The force of electric current through a circuit.

Glossary: W

Water
  • One gallon of water = 8.34 lbs.
  • One Cubic Foot of Water = 62.4lbs.
  • One Cubic Foot of Water = 7.38 gallons.
  • One gallon of water = 231 cubic inches.
  • One BTU = The quantity of heat to raise the temperature of one pound of water 1degree between 32degrees and 212degrees F
Kilowatt Heating Guide
Amount of Liquid
Temperature Rise, °F
Cubic Feet
Gallons
Kilowatts to heat in one hour
20°
60°
100°
140°
170°
.66
5
0.3
0.8
1.6
2.7
2.9

1.3

10
0.5
1.6
3.2
5.3
5.8
2.7
20
1.1
3.2
6.0
9.5
11.5
3.3
25
1.3
4.0
7.5
12.0
14.5
6.7
50
2.7
8.0
15.0
24.0
29.0
13.4
100
5.5
16.0
30.0
48.0
57.5
20.0
150
8.0
24.0
45.0
72.0
86.5
26.7
200
11.0
32.0
60.0
95.0
115.0
Gas Burner Approximate BTU/HR Heating Guide
Gallons BTU/HR
1-3 5,000
3-4 7,000
3-5 8,000
5-8 12,000
8-16 20,000
8-40 30,000
Watt
A measurement of electrical power. Rate at which one volt can push one ampere through an electrical circuit
One watt =.0569 BTU per minute
Approximate Percent Rated Watts When Reduced Voltage Is Applied:
  • 120 Volt Heater On 115 Volt = 92%
  • 120 Volt Heater On 110 Volt = 84%
  • 120 Volt Heater On 105 Volt = 77%
  • 240 Volt Heater On 220 Volt = 84%
  • 240 Volt Heater On 208 Volt = 75%
  • 240 Volt Heater On 120 Volt = 25%
  • 480 Volt Heater On 440 Volt = 84%
OHM'S LAW WATTS = AMPERAGE² x OHMS
WATTS = VOLTS x AMPERAGE
W.C.
Water Column