(a) No person may operate a low-pressure distribution system at a pressure high enough to make unsafe the operation of any connected and properly adjusted low-pressure gas burning equipment.

(b) No person may operate a low-pressure distribution system at a pressure lower than the minimum pressure at which the safe and continuing operation of any connected and properly adjusted low-pressure gas burning equipment can be assured.

(c) Each operator shall maintain a pressure throughout its low-pressure distribution systems, as measured at the consumer's end of the service line, of not less than four inches nor more than 12 inches of water column gauge.

(d) The maximum daily pressure variation shall not exceed a total range of 50 percent of the maximum gauge pressure experienced during the day at any point in the low-pressure distribution system, as measured at the consumer's end of the service line. Overpressure protection devices may be set at levels above the normal maximum operating pressure. The capacity of overpressure protection devices shall be sufficient to prevent a pressure buildup in excess of two psig (14 kPa) on the low-pressure distribution system.