Release Check Valves: RC18 & RC 18-040

RC18 RELEASE CHECK VALVE

RC18 employs a normally closed valve to seal against pump vacuum without leaking. When a compressed air supply is applied, the release valve shifts open at only 5 psi (0.3 bar) so that a full-flow burst of air can quickly dissipate (blow-off) system vacuum. Once shifted, the valve doesn’t try to close, but remains open until the compressed air source is removed then it automatically resets to a closed position. RC18 should be used for high-flow vacuum release applications such as those involving vacuum reservoirs or larger mono-stage or multi-stage vacuum pumps.

Competitive products are simply check valves having a 30-40 psi (2-3 bar) cracking pressure. The high cracking pressure is necessary to insure a tight seal against vacuum developed by the pump, but when a compressed air supply is applied to open the valve for blow-off, the internal spring immediately tries to close the valve as soon as flow begins. This has the effect of subtracting the valve cracking pressure from the blow-off air pressure, so these systems normally have to operate above 50 psi (3.3 bar), which wastes compressed air.

RC18-040 RELEASE CHECK VALVE

RC18 operates the same as RC18 but includes a .040” (1mm) balancing orifice to meter the air flow when multiple release checks are supplied air from the same blow-off control valve. Without a balancing orifice in each release check, air would follow the path of least resistance, so some release valves could be starved for air while others would have a flow many times greater than necessary.