Vacuum check valves are used to hold downstream vacuum whenever the vacuum source is removed or lost. Internally, a normally closed valve allows vacuum flow in the pump direction, but seals off whenever vacuum flow stops to prevent reverse flow. Whenever a vacuum check valve is used in a system, some provision must be made to release the trapped vacuum as required by system parameters. The RC18 and RC18-040 release check valves are designed for this purpose.
One application for VC check valves is for Energy Saver circuits having a vacuum storage tank to accumulate and store vacuum for highvolume, short duration, flow rate requirements. More commonly, a VC check valve with RC release check would be used with a single suction cup so a non-porous, high value, work piece wouldn’t be immediately dropped if the system vacuum source were lost. Depending on the condition of all vacuum system components, the trapped vacuum will eventually leak down. To increase the time delay interval, a volume chamber can be added to the auxiliary port. If the volume chamber is equal to twice the cup internal volume, the time delay interval will be approximately tripled, and so forth. VC18 should be used with 50mm and smaller suction cups while VC12 should be used with 75mm and larger suction cups with ½” fittings. |
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