Pressure Regulators and Orifices Flashcards
In a regulator what are the restricting, the measuring and the loading elements?
Orifice is the restricting element
Diaphragm is the measuring element
Spring is the loading element
What effect does turning the adjustment screw have on a regulator?
Clockwise = pressure increase
Counter clockwise = pressure decrease
What is the maximum amount of gas vented through a leak limiting device on a 2 psi or less application?
1 cubic foot per hour for propane
2.5 cubic feet per hour for natural gas
What is the function of a vent suppressor?
Keeps diaphragm from slamming open and shut
Maintains steady pressure
Most controls on residential appliances are rated for a maximum operating pressure of?
0.5 psig (14” w.c.)
What is the most common type of appliance regulator that is incorporated into appliance regulators?
Servo regulator
It is incorporated into combination gas valves
What is the maximum first stage regulator setting for propane?
10 psi
Once the first stage propane regulator is set for 10 psi, the gas enters the second stage regulator where it is reduced to what pressure?
11” wc
A dual stage propane regulator reduces pressure to what?
11” wc
A regulator must be installed with a manual shut off located where?
Upstream of the regulator
In what position should regulators be installed?
Horizontally with the vents on the vertical plane
What type of copper is permitted to be used underground?
- Type K
- Type L or G may be used if they are externally coated with a polyethylene or pvc resin
If indoor installation of a propane regulator is required, where must it be located?
Within 3 feet of where the gas line enters the building
What are the benefits of a 2 stage regulator system on propane?
- recommend for smaller gas lines
- gives appliances a more constant delivery pressure
- provides flexibility for future expansion
- less chance of freeze up at the regulator
What is the maximum allowed gas pressure in a single family dwelling?
2 psig
What are acceptable materials used for venting a regulator to the outdoors?
Steel pipe or tubing
Copper tubing
Aluminium tubing
How do you size a vent line on a regulator?
At least equal to the connection on the regulator, but minium 1/4”
A diaphragm gas valve or combination gas valve with inlet pressures less than ___ psig used for _____ gas only, may have the vent line terminate where?
0.5, natural gas
The vent line may terminate at a constant burning pilot (standing pilot)
How do you size the length of a regulator vent line?
Increase one pipe size for every 50 feet of vent line length. The increase in size is made at the connection on the outlet of the device
Can the vents from 2 or more relief devices be connected into a common vent?
Yes
All outdoor vent terminals must have what?
Termination fitting installed that will prevent water, insects or other foreign material from entering the vent pipe
Where must a propane appliance regulator with a leak limiter be installed?
In a well ventilated area such as outside
What is one problem that can occur from an undersized regulator?
Too low outlet pressure
What is one problem that may occur when a regulator is over sized?
Noisy during operation
Where does external freeze up occur on a regulator?
In the atmospheric chamber above the diaphragm or over the regulator vent
What can you do to reduce external regulator freeze up?
Install the regulator in such a manner that moisture entering the atmospheric chamber through the vent opening is at a minimum
Regulators installed outdoors must have the vent pointing where?
Down
As gas pressure decreases what happens to the temperature of the gas?
It drops as well
Pressure drop = temp drop
A regulator with a lot of frost on the exterior head and body is a good indication of what?
Undersized regulator
What must every aerated burner have?
An orifice
What are the 2 basic functions of an orifice?
Regulates gas volume
Controls velocity
What are the most commonly used orifices?
Plug orifices
What color are natural gas pilot orifices?
What color are propane pilot orifices?
Silver metal color
Dark brown or black
What is considered to be high pressure gas?
Over 14” w.c.
When may a dual stage regulator be used on a propane system?
For temporary applications only
Pressure controls without relief devices should be vented how?
Seperatly
How far must a regulator vent termination be from a moisture exhaust duct (dryer vent)?
3’ (1m)
For inlet pressure on a regulator of up to 5 psi, the discharge set point on the line relief shall be what?
No less than 2 times and no more than 3 times the operating pressure (outlet pressure) of the regulator
For inlet pressure on a regulator of greater than 5 psi, the discharge set point on the line relief shall be what?
No less than one and a half times and no more than 2 times the operating pressure (outlet pressure) of the regulator
What are the calorific values of propane and natural gas?
Natural gas = 1000 Btu/cubic ft.
Propane = 2500 Btu/cubic ft.
What orific size would you need if you used a number 37 drill bit?
35 orifice (2 sizes smaller)
How is an orifice drilled?
In the direction of gas flow
What is the equation for clocking the meter?
(Size of proving dial / number of seconds)
Multiply by 3600
Multiply by 1000 for Natural Gas
Multiply by 2500 for Propane
