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:

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

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
FOR RESISTANCE IN 3-PHASE CIRCUIT (ACROSS ANY TWO TERMINALS0

Ohm's Law Calculation Examples

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

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

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