The CL31 Series is designed to provide extremely accurate regulation of intermediate volumes of gas (to 4000 SCFH) at elevated pressures (1 to 20 PSIG). The CL31R features a relief-type pilot regulator to provide token relief and to prevent excess loading pressure from entering the main regulator should the pilot regulator fail. The CL31N features a non-relief pilot regulator and can be used for outlet pressures over the entire range without changing the pilot adjustment spring.