Pressure Regulators And Orifices Flashcards
Function Of a regulator
Reduces and maintains a set pressure while compensating for demand changes
The Restricting Element (orifice and valve plug)
The restricting element (orifice and valve plug) is the point at which the gas entering a regulator goes through the greatest restriction
What is a leak limiting device used for?
To limit the amount of gas escaping if the diaphragm ruptures 1 cu.ft./hr for propane and 2.5 cu ft/hr for natural gas
When is a leak limiting device used
For 2psig or lower pressures in a well ventilated space only
What two devices are used to control excess pressure?
Internal and external relief valves
How is regulator freeze up identified
By a lack of gas to the burners (slow or sluggish operation). Freeze up is initially identified by a lack of gas to burner
What does a plugged vent cause
Excessively high pressure
What position does gas valve fail in
Closed
When Venting two or more pressure regulators together
The area of the single vent line shall have an area not less than twice the area of the connected bleed vents
When venting two or more over pressure relief devices together
The area of the single vent line shall have an area equal to the largest relief opening plus 50% of the total area of the other relief valve openings (5.5.2)
Name the four types of pressure regulators
Service
System
Appliance
Servo
What close the valve stem
Gas pressure
Name the three elements of a regulator
The restricting element (orifice or valve stem)
The measuring element (diaphragm)
The loading element (spring or weight)
How are ball check limiting devices installed
Regulator vent to restrict the volume of gas escaping from the regulator vent in case of diaphragm rupture
Allowable leakage in event of diaphragm rupture for CH4
2.5 cubic foot per hour
Allowable leakage in event of diaphragm rupture for C3H8
1 cubic foot per hour
Ball check limiting devices restricted to
2 PSIG
Who can install and service the service regulator for natural gas
Only the utility company, usually set at 7” w.c.
upon request it can be set at higher point
System regulator is used for
Where building gas pressure is higher than what is require by the appliance. Low pressure 14” w.c or less
Appliance regulator is used for
Is found in gas valve train or appliance manifold.
Without appliance regulator, the appliance is subject to pressure fluctuation.
Servo Regulator
The most common type of appliance regulator incorporated into a combination gas valves.
Pilot operated
Two diaphragms available
Single Diaphragm, 1 Diaphragm
Self-operating regulator
Propane, First stage regulator
Maximum pressure output 10 PSI (recommended between 5-10 PSI)
Input can be as high as 200PSI
Propane, Second stage regulator
Inlet: 10PSI max
Outlet: 11” w.c
