Propane Gas Regulator Information
This information is for informative purposes only. All LP Gas installations must be performed only by qualified installers in accordance with all applicable codes and industry standards.
The regulator truly is the heart of an LP-Gas installation. It must compensate for variations in tank pressure from as low as 8 psig to 220 psig – and still deliver a steady flow of LP-Gas at 11” w.c. to consuming appliances. The regulator must deliver this pressure despite a variable load from intermittent use of the appliances. The use of a two-stage system offers the ultimate in pin-point regulation. Two-stage regulation can result in a more profitable LP-Gas operation for the dealer resulting from less maintenance and fewer installation call-backs.
Single Stage vs. Twin-Stage Regulation
NFPA 58 (1998) states that single stage regulators shall not be installed in fixed piping systems. This requirement includes systems for appliances on RVs, motor homes, manufactured housing, and food service vehicles. In these cases a twin-stage regulator must be used. The requirements do not apply to small outdoor cooking appliances, such as gas grills, provided the input rating is 100,000 BTU/hr or less.
Two Stage Regulation
Two-Stage regulation has these advantages: Uniform Appliance Pressures
The installation of a two-stage system–one high pressure regulator at the container to compensate for varied inlet pressures, and one low pressure regulator at the building to supply a constant delivery pressure to the appliances–helps ensure maximum efficiency and trouble-free operation year round. Two-stage systems keep pressure variations within 1” w.c. at the appliances.
Reduced Freeze-ups/Service Calls
Regulator freeze-up occurs when moisture in the gas condenses and freezes on cold surfaces of the regulator nozzle. The nozzle becomes chilled when high pressure gas expands across it into the regulator body. Two-stage systems can greatly reduce the possibility of freezeups and resulting service calls as the expansion of gas from tank pressure to 11” w.c. is divided into two steps, with less chilling effect at each regulator. In addition, after the gas exits the first-stage regulator and enters the first-stage transmission line, it picks up heat from the line, further reducing the possibility of second-stage freeze-up.
Economy of Installation
In a twin-stage system, transmission line piping between the container and the appliances must be large enough to accommodate the required volume of gas at 11”w.c.. In contrast, the line between the first and second-stage regulators in two-stage systems can be much smaller as it delivers gas at 10 psig to the second stage regulator. Often the savings in piping cost will pay for the second regulator. In localities where winter temperatures are extremely low, attention should be given to the setting of the first stage regulator to avoid the possibility of propane vapors recondensing into liquid in the line downstream of the first-stage regulator. For instance, if temperatures reach as low as -20ºF, the first-stage regulator should not be set higher than 10 psig. If temperatures reach as low as -35ºF, the setting of the first-stage regulator should not be higher than 5 psig. As an additional benefit, older single-stage systems can be easily converted to two-stage systems using existing supply lines when they prove inadequate to meet added loads.
Allowance for Future Appliances
A high degree of flexibility is offered in new installations of two stage systems. Appliances can be added later to the present load– provided the high pressure regulator can handle the increase– by the addition of a second low pressure regulator. Since appliances can be regulated independently, demands from other parts of the installation will not affect their individual performances.