SRB Combination Reducing - Relief Regulators serve a dual function. They relieve upstream pressure while at the same time controlling downstream pressure. The controlled pressure downstream is equal to the upstream pressure minus the spring setting. Springs are color-coded in cataloged pressure ranges. Inlet pressures to 25 psig operating; maximum surge to 50 psig without damage. FEATURESAvailable in sizes 3/4'' through 3'' NPT.Drip tight shut-off below start to open pointBalanced valve designSynthetic reinforced diaphragms - for air, all fuel & inert gasesInlet pressures to 25 psig operating, maximum surge to 50 psig without damageRugged proven designStandard SRB series operating temperatures to 150°F CAPACITY TABLE Relief Regulator Catalog Number Pipe Size NPT Capacities in SCFH of Various Specific Gravity Gases @ 14" W.C. Pressure Drop 0.4 0.6 1.0 1.5 2.0 SRB 6 3/4" 1,230 1,000 780 630 550 SRB 8 1" 2,400 2,000 1,500 1,200 1,100 SRB 12 1-1/2" 4,900 4,000 3,100 2,500 2,200 SRB 20 2-1/2" 12,300 10,000 7,800 6,300 5,500 SRB 24 3" 21,000 17,000 13,000 11,000 9,200 SPRING RANGES Spring Number Spring Color Spring Adjustment Range Start to Stroke Setting Minimum Maximum 4 Red 1" W.C. 8" W.C. 16 Orange 7" W.C. 30" W.C. 48 White 12 osi 48 osi Spring #48 not available on #SRB-20 and SRB-24