American Meter: Industrial Natural Gas Regulator 1813B***CALL FOR AVAILABILITY*** Product Description Inlet Pres.: 1 125 PSI; Outlet Pres.: 3. 5 W. C. 5 PSI; Max Flow: 20,000 SCFH The 1813B is a full capacity internal relief regulator capable of reaching 20,000 SCFH at higher inlet pressures. 1800 Series low pressure models have a maximum inlet pressure of 125 psi and offer outlet pressures ranging from 3. 5" w. c. to 5 psi. The 1800 Series can be ordered as Full Relief, Partial Relief or No Relief