FAQ’s & Manuals

FAQ’s & Manuals

Q: What causes a valve to leak?

A: There could be a number of reasons why a valve might leak. The most common is a dirty or damaged gate O-ring. The second most common reason could be that the Viton or copper bonnet gasket is also dirty or damaged. Another cause is a leak in the bellows which can be detected with a leak detector on the actuator.

Q: What happens to the gate when power is lost?

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: What happens to the gate when air pressure is lost?

A: If the valve is in the open position then it depends on the orientation of the valve. If the valve is horizontal or vertical actuator down then the gate will remain open. If the valve is vertical actuator up then the gate will pull down. If the valve is in the closed position it depends on the size of valve and whether or not a HVA solenoid was installed. If the valve was purchased without a solenoid then it is adjusted to lock-over-center which means that the internal linkage mechanism will keep it closed. If the valve was purchased with a HVA solenoid and is 6″ ID and smaller than it is also adjusted to lock-over-center. If the valve is 8″ ID and larger there is a brass check valve in the solenoid that will maintain pressure to keep it closed only if there are no leaks in the air line and air fittings.

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.

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: How often should preventative maintenance be performed on a valve?

A: Preventitive maintenance is application dependant. The harsher/dirtier the process the more frequent cleaning and maintenance is needed.

Q: What preventative maintenance needs to be done on a valve?

A: Cleaning and regreasing of the O-ring and moving parts.

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: 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: 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: 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: 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: 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.