255.197 Control of the pressure of gas delivered from high pressure distribution systems.

(a)If the maximum actual operating pressure of the distribution system is 60 psig (414 kPa) or less and a service regulator having the following characteristics is used, no other pressure limiting device is required.#

(1)The regulator is capable of reducing distribution line pressure to pressures recommended for household appliances.#

(2)It has a single port valve with proper orifice for the maximum gas pressure at the regulator inlet.#

(3)The valve seat is made of resilient material designed to withstand abrasion by the gas, impurities in gas, cutting by the valve, and also to resist permanent deformation when it is pressed against the valve port.#

(4)The pipe connections to the regulator do not exceed two inches (51 millimeters) in diameter.#

(5)The regulator, under normal operating conditions, is able to regulate the downstream pressure within the necessary limits of accuracy and to limit the build-up of pressure under no- flow conditions to prevent a pressure that would cause the unsafe operation of any connected and properly adjusted gas utilization equipment.#

(6)The regulator is self-contained with no external static or control lines.#

(7)The regulator is of a type including a relief valve which is vented to the atmosphere with the relief valve set to open so that the pressure of the gas going to the customer does not exceed the maximum safe pressure as established by this Part.#

(b)If the maximum actual operating pressure of the distribution system is 60 psig (414 kPa) or less, and a service regulator is used that does not have all of the characteristics listed in subdivision (a) of this section or if the gas contains materials that seriously interfere with the operation of service regulators, there must be suitable protective devices to prevent unsafe overpressuring of the customer's appliances if the service regulator fails.#

(c)If the maximum actual operating pressure of the distribution system exceeds 60 psig (414 kPa), unless higher pressure is needed by the customer or it is impractical or unsafe to regulate the pressure outside, one of the following methods must be used to regulate and limit the pressure of gas delivered to the customer.#

(1)A service regulator having the characteristics listed in subdivision (a) of this section, and another regulator located upstream from the service regulator. The upstream regulator may not be set to maintain a pressure higher than 60 psig (414 kPa). A device must be installed between the upstream regulator and the service regulator to limit the pressure on the inlet of the service regulator to 60 psig (414 kPa) or less in case the upstream regulator fails to function properly. This device may be either a relief valve or an automatic shut-off that closes if the pressure on the inlet of the service regulator exceeds the set pressure (60 psig [414 kPa] or less), and remains closed until manually reset.#

(2)A service regulator and a monitoring regulator set to limit, to a maximum safe value, the pressure of the gas delivered to the customer.#

(3)A service regulator with a relief valve set to open so that the pressure of gas going to the customer does not exceed a maximum safe value. The relief valve may either be built into the service regulator or it may be a separate unit installed downstream from the service regulator. Either of these combinations may be used alone only in those cases where the inlet pressure on the service regulator does not exceed the manufacturer's safe working pressure rating of the service regulator, and may not be used where the inlet pressure on the service regulator exceeds 125 psig (862 kPa). For higher inlet pressure, the methods in paragraph (1) or (2) of this subdivision must be used.#

(4)A service regulator and an automatic shut-off device that closes upon a rise in pressure downstream from the regulator and remains closed until manually reset.#

(5)Any service line operating at 125 psig (862 kPa) or more serving customers requiring regulation of the line pressure is to be equipped with either an excess flow valve or must have the first stage regulator located at least 50 feet (15.2 meters) from the building or, if 50 feet (15.2 meters) cannot be attained without entering the roadway, located at the property line.#