FAQs Archive - HVA - Vacuum Valves

Q: Q: What length of bolts should be used in the flanges?

A: Bolts longer than the thickness of both mating flanges will damage the body panels and destroy the seal surface area for the gate O-ring. For best results, always use bolts that are at least 1/4-inch (6.4 mm) shorter than the thickness of both mating flanges.

Q: Q: What orientation can a valve be mounted?

A: HVA gate valves can be mounted in any orientation. The standard orientation is horizontal. If the valve is 8″ ID and larger and will be mounted vertically with the actuator up or down then the speed controls need to be adjusted so the cycles times match those seen under Q: What are the opening and closing speeds of various sized gate valves?

Q: Q: What may cause a valve gate to get stuck?

A: There are three main reasons why a gate may get stuck. First, is that the wheels and bearings in the gate/carriage assembly have seized. Second, the flanges have been over tightened and are compressing the body causing the gate to seize. Finally, too long of bolts used in the flanges can dent the inside of the body.

Q: Q: How much air pressure is needed to operate a pneumatic gate valve?

A: Depending on the size the pressure ranges from 20 to 80 PSI. Air pressure should never exceed 80 PSI.

Q: Q: What are the opening and closing speeds of various sized gate valves?

A: Cycle times are as follows: 1.5″ thru 3″ ID = 1.5 to 2 sec to open, 1.5 to 2 sec to close 4″ thru 8″ ID = 2.5 to 3 sec to open, 2.5 to 3 sec to close 10″ thru 12″ = 4.5 to 5 sec to open, 4.5 to 5 sec to close 14″ thru 21″ = 7 to 10 sec to open, 7 to 10 sec to close.

Q: Q: Where is the model and serial number found on a gate valve?

A: It is either found on the serial tag which is located on the actuator or the serial number itself can be found etched on the body flange near the bonnet plate.

Q: Q: How does a gate valve stay closed?

A: If the valve was provided with a solenoid from HVA then it is adjusted to close. If the valve was not provided with the solenoid then it depends on the system and the way it was plumbed by the OEM.

Q: Q: What causes the gate on a manual valve to open or close on its own?

A: The tension in the manual bearing block assembly has loosened and needs to be tightened.

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