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Part # GCTRM Rev 3 (12/10/09)
Page 50
Gas Pressure Regulators
Purpose Of A Gas Pressure Regulator
Gas pressure regulators have two main purposes, to
reduce supply main pressure to safe operating pressures of
connected appliances and to maintain constant downstream
pressure, regardless of changes in the gas flow or upstream
pressure variations.
Supply gas pressure is usually higher than the safe operating
pressures of connected appliances.
If an appliance receives too much fuel, it will over fire. If it
receives too little fuel, it will under fire. It will produce too
much or too little heat. Combustion characteristics could
change resulting in carbon monoxide generation. The
appliance may not work properly or efficiently.
Main Categories Of Regulators
Service Regulator
is used in natural gas systems to
reduce service line pressure to building line pressure at
the gas meter. In propane, they are used to reduce the
service line pressure to building line pressure and placed
between the storage container and the building.
System Regulator
is used to reduce building line
pressure when pressure required by a system of
appliances or equipment is less than the pressure in the
pipe where it enters the building.
Appliance Regulator
is used to reduce building line
pressure to the pressure required by the appliance. It is
often built into a combination control.
Downstream refers to the flow of gas after it has passed the
regulator. Upstream refers to the flow of gas before it passes
through the regulator.
A manual shut-off valve must be installed upstream of the
regulator so that the regulator may be isolated for servicing.
System regulators may require an internal relief device or a
line relief device to allow excess gas to be vented outdoors.
Some vents contain a leak-limiting device to restrict flow
so that gas accumulation does not reach dangerous levels.
These are not required to vent outdoors.
The pressure setting on a line relief device should not be
higher than the lowest rated item downstream of the relief
device. Most natural and all propane relief devices must be
vented outdoors.
Hydrostatic Relief Device
A hydrostatic relief device is used in propane systems. They
are to be installed between two valves in a propane system.
If liquid propane is trapped between two closed valves in
piping or hose, it will begin to expand as its temperature
increases. The hydrostatic relief device relieves this pressure
and prevents the pipe from bursting.
Venting Of Regulators
Vent lines must be protected from damage including water
entry and inset damage. Vent line size must be at least the
nominal pipe size of the vent outlet of the pressure regulator
but not less than 0.25”.
Individual vent lines may be connected to a single vent line
provided this single vent line is twice the area of the total
area of the connected bleed vent lines. Vent lines must be
increased by one pipe size diameter for every 50 ft. The
increase must be made at the regulator vent outlet.
In natural gas, when using a diaphragm or combination
control valve, relieved gas may be vented to the low-inlet
pressure appliance combustion chamber. It must have a
continuous pilot.
Terminology
Set Point
is the desired outlet pressure of the regulator. As
flow rate increases, the downstream pressure decreases.
Lock up
is the pressure above the set point that is used to
shut the regulator off tight. To make a tight seal, the regulator
must increase the downstream pressure to force the disk into
the knife-edge. This is called lock up pressure.
Droop and offset
describe the downstream pressure drop
set point. At this point, the valve is opened and there is an
increase flow of gas. Droop is a percentage of the set point
pressure. The accuracy of a regulator is determined by the
amount of flow it can pass for a given amount of droop. The
closer a regulator is to the set point, the more accurate it is.
The Loading Element
is used to counterbalance the
downstream pressure. It is usually a spring.
The Measuring Element
is usually a diaphragm. It is used
to measure the changes in the downstream pressure. It is
attached by a stem to the restricting element so that they
both move together.
Summary of Contents for G Series
Page 2: ...Part GCTRM Rev 3 12 10 09 Page 2...
Page 4: ...Part GCTRM Rev 3 12 10 09 Page 4...
Page 5: ...Part GCTRM Rev 3 12 10 09 Page 5 Section 1 Model Number Identification...
Page 17: ...Part GCTRM Rev 3 12 10 09 Page 17 Section 2 Serial Number Identification...
Page 20: ...Part GCTRM Rev 3 12 10 09 Page 20...
Page 21: ...Part GCTRM Rev 3 12 10 09 Page 21 Section 3 Certification Markings...
Page 24: ...Part GCTRM Rev 3 12 10 09 Page 24...
Page 25: ...Part GCTRM Rev 3 12 10 09 Page 25 Section 4 Properties And Characteristics of Fuel Gases...
Page 27: ...Part GCTRM Rev 3 12 10 09 Page 27 Section 5 Operation Of Controls...
Page 31: ...Part GCTRM Rev 3 12 10 09 Page 31 Section 6 Gas Valves And Adjustments...
Page 36: ...Part GCTRM Rev 3 12 10 09 Page 36...
Page 48: ...Part GCTRM Rev 3 12 10 09 Page 48...
Page 49: ...Part GCTRM Rev 3 12 10 09 Page 49 Section 8 Gas Pressure Regulators...
Page 52: ...Part GCTRM Rev 3 12 10 09 Page 52...
Page 53: ...Part GCTRM Rev 3 12 10 09 Page 53 Section 9 Thermocouples And How They Work...
Page 55: ...Part GCTRM Rev 3 12 10 09 Page 55 Section 10 Trouble Shooting The Oven Pilot Safety System...
Page 65: ...Part GCTRM Rev 3 12 10 09 Page 65 Section 13 Gas Technician s Glossary...
Page 70: ...Part GCTRM Rev 3 12 10 09 Page 70...
Page 71: ...Part GCTRM Rev 3 12 10 09 Page 71 Section 14 Range Wiring Diagrams...
Page 75: ...Part GCTRM Rev 3 12 10 09 Page 75 3056100 US Range C836C Cuisine Series...
Page 76: ...Part GCTRM Rev 3 12 10 09 Page 76 229064 US Range 836C Cuisine Series...
Page 77: ...Part GCTRM Rev 3 12 10 09 Page 77 2706601 US Range Px S Series Left Single RC Oven...
Page 78: ...Part GCTRM Rev 3 12 10 09 Page 78 2706602 US Range Px S Series Right Single RC Oven...
Page 79: ...Part GCTRM Rev 3 12 10 09 Page 79 2706603 US Range Px S Series 2 RC Ovens...
Page 80: ...Part GCTRM Rev 3 12 10 09 Page 80 4514771 US Range Px SX Series Left Single RC Oven...
Page 81: ...Part GCTRM Rev 3 12 10 09 Page 81 4514772 US Range Px SX Series Right Single RC Oven...
Page 82: ...Part GCTRM Rev 3 12 10 09 Page 82 4514774 US Range Px SX SeriesTwo RC Ovens...
Page 83: ...Part GCTRM Rev 3 12 10 09 Page 83 2529700 ME MSTE 40RC Electric Spark...
Page 84: ...Part GCTRM Rev 3 12 10 09 Page 84 2529701 M MS 40RC...
Page 85: ...Part GCTRM Rev 3 12 10 09 Page 85 2529600 M MS 40 Electric Spark...
Page 86: ...Part GCTRM Rev 3 12 10 09 Page 86 2444200 Sentry Electric Spark...
Page 87: ...Part GCTRM Rev 3 12 10 09 Page 87 2444300 STE286RC STE284RC Left ST283RCE...
Page 97: ...Part GCTRM Rev 3 12 10 09 Page 97 Section 15 Service Bulletins...
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