9 Regulator Categories

There are four categories of pressure regulators as defined in the CSA B149.1 Natural Gas and Propane Installation Code:

• Service regulators
• Appliance regulators
• Line pressure regulators
• High pressure regulators

Service regulators

Service regulators are installed on a service line to reduce the gas pressure to the desired building pressure. The Natural gas meter sets are provided with a service regulator (Figure 14), which is installed by the gas utility rather than the gasfitter.

Service regulator

Figure 14 Natural gas meter set

For propane systems, service regulators are installed by the gas technician/fitter between the storage container and the building. Propane service regulators are also called second stage regulators or twin stage regulators (Figure 15).

Figure 15 Propane service regulators

The maximum delivery pressures within various types of buildings are listed in section 5.1 of the CSA B149.1 gas code. For example the maximum allowed pressure in a single-family dwelling is 2 psig.

Appliance regulators

Appliance regulators are located on the valve train of the appliance to reduce the inlet pressure of the appliance to the appropriate manifold pressure required for proper burner performance (Figure 16). The main purpose of the appliance regulator is to maintain a relatively constant gas outlet pressure to the burner(s) to assure constant, even flame at the main burners.

Appliance regulator

Figure 16 Appliance regulator in valve train

Most natural gas appliances require a manifold pressure of 3” to 4” WC, while propane appliances typically require 10” to 11” WC. Residential and commercial appliances will typically have an appliance regulator with a maximum inlet pressure of 0.5 psig (14” WC).

For appliances with inputs less than 400 MBH the appliance regulator is often included as part of a combination gas valve (Figure 17). These combination valves often employ servo operated regulators that can have the manifold pressures stepped or modulated down to as low as 0.5” WC. Combination gas valves will be looked at in greater detail in B1 LT4.

Regulator

Figure 17 Appliance regulator as part of a combination gas valve

Line pressure regulators

The service regulator will often deliver a building line pressure that exceeds the maximum allowable pressure specified for the gas appliance. In these cases, line pressure regulators are installed between the building’s service regulator, or LP-gas 2 psig (13.8 kPa) service regulator, and the gas appliance. For example, a 2 psig service will need to be reduce to a maximum of 0.5 psig (14” WC) as that is the maximum inlet pressure to most appliance regulators (Figure 18).

Figure 18 Line Pressure Regulator

Line pressure regulators are classified in accordance with their intended application and are designated either Class I or Class II.

• Class I regulators have a maximum outlet pressure setting of ½ psig as they are used primarily with residential and light commercial appliances that have ½ psig maximum rated inlet pressures. They can be certified for a rated inlet pressure of 2, 5, or 10 psig.
• Class II regulators have a maximum outlet pressure setting of 2 psig as they are used primarily with industrial appliances that have 2 psig maximum rated inlet pressures. They can be certified for a rated inlet pressure of 5 or 10 psig.

Line pressure regulators used for installations with a supply pressure exceeding 2 psig require a tested and approved overpressure protection device (OPD), to prevent the outlet pressure from exceeding the rated pressure of the system components.

High pressure regulators

A high pressure regulator is similar to a line pressure regulator except it is used for applications where the inlet gas pressure is greater than 10 psig (70 kPA) and an outlet pressure is greater than 2 psig (14 kPA). An example could be if the gas service was routed directly into the mechanical room of a hotel at the maximum allowable pressure of 20 psig to serve the boiler loads, and then continued from the mechanical room into the hotel to serve other loads. This would require an additional regulator to reduce the gas pressure to a maximum of 5 psig before it left the mechanical room. The other equipment throughout the hotel would still require one of more line pressure regulators to reduce the pressure to ½ psig for the appliances.