Regulator Assignment 1 + 2 Flashcards
What are the two main purposes of gas pressure regulators?
- Reduce and maintain pressure downstream
- Regulate and adjust pressure
What are the four categories of gas pressure regulators?
- Service
- Line
- Appliance
- Two-stage
What is “lock-up pressure” and how do you check it?
Pressure above set-point that shuts regulator down
Close the valve and measure downstream pressure
Where is the hydrostatic relief valve used?
Liquid propane system for when propane is tapped between two shut off valves
What must be the size of the vent piping from a relief device?
Same size as the vent opening
What are the three elements of a direct operated regulator?
loading, measuring, restricting
When flow rate increases through a regulator, what happens to the downstream pressure?
IT decreases.
What is the maximum allowable propane pressure in a building?
20-25psig
What controls the downstream pressure in a regulator?
Loading element/spring
What is the difference between a zero-governor and an air/gas ratio regulator?
Zero gov keeps downstream pressure at 0 and only allows flow through negative pressure signal & air/gas keeps ratio constant even during air pressure changes
What type of regulator arrangement is required in all permanent propane installations?
Two-stage
Will gas Flo be interrupted by changing a propane cylinder if an automatic changeover regulator is used on the installation?
No. Auto-changeovers allow no interruption
What 5 factors need to be considered before selecting a regulator?
- inlet pressure
- outlet pressure
- pipe size
- gas type
- btuh
Under what conditions can a leak limiter be used?
Ventilated space only
Maximum allowable leakage rate for leak limiter installed on a natural gas regulator?
2.5ft3
Maximum allowable leakage rate for leak limiter installed on a propane regulator?
1ft3
Should the arrow on a regulator body point upstream?
NO
What is the minimum clearance allowed between the vent termination of natural gas regulator and a building opening?
36”
What is the maximum allowable pressure downstream of a pressure controlling device?
Max allowable inlet pressure of appliance furthest downstream
What are the most commonly used overprotection devices?
Relief valves
Does a relief valve decrease a regulators capacity?
No
What measures the system pressure when using a direct operated relief valve?
diaphragm senses upstream pressure via a sensing line
What types of overpressure protection incorporates a restricting element?
All relief types
if the type of system and the pressure ranges safely handled by the system are known, how should a relief valve be chosen? (3)
- continuity - can flow be interrupted
- safe discharge - where will gas go
- detectability of failure - how does it
Does an overpressure shut-off (OPSO) automatically reset?
NO, manual
What would happen if a regulator vent became blocked with the regulator in the open position?
It can not close
Which type of monitor, wide-open or working, is less likely to have operating problems? Why?
Working, because it is being exercised
What are the min and max allowed set pressures for a line relief device installed on a 2psi piping system?
We do not need a relief
