Finishing and Fluid Handling FAQ

Finishing and Fluid Handling FAQ

Answers To Your Questions About Finishing And Fluid Handling

As the specialists in finishing and fluid handling, OTP has the answers you seek related to your equipment, systems and fluid handling challenges. Below are responses to the questions we most often hear. If you need additional information, simply contact our knowledgeable staff today.

Q: Why is there a wet cup at the top of my piston pump?

A: Add throat seal lubricant to the wet cup to lubricate the packing and reduce the amount of air and moisture introduced into the pump. The piston pump manufacturer will offer a throat seal lubricant recommended for this use.

Q: I just repacked my piston pump and it is leaking from the top of the pump where the shaft goes in. How do I fix this and keep it from happening again?

A: Tighten the packing nut down to be sure the new packing has been properly compressed. However, be careful not to over tighten, which could restrict the movement of the piston pump shaft. If the packing nut is already all the way in, you may have excessive shaft wear or the packing may not have been properly installed.

To prevent premature packing and shaft wear, always maintain a level of throat seal lubricant in the wet cup.

Q: My 2 ball pump is leaking out the packing. Do I need to rebuild it?

A: Some 2 ball pumps have adjustable packing. These can be adjusted by relieving all fluid pressure from the system and tightening the packing nut or solvent cup (refer to your owner’s manual).

Q: Why does an HVLP spray gun produce less VOC?

A: The amount of solvent—volatile organic compounds (VOC)—is the reason for the lower levels of VOC’s, not the type of gun. The HVLP gun is capable of spraying high viscosity fluids, which contain lower levels of VOC’s. The EPA defines HVLP spray as having a maximum atomization air pressure inside the fluid cap of 10psi, which further reduces the amount of VOC released to atmosphere.

Q: My piston pump or diaphragm pump has too much “dropoff” when it changes direction. What should I do?

A: Install a downstream pressure regulator to control to the pressure you desire. Alternately, you can install a suppressor to the system to reduce the pressure fluctuations as the pump shifts.

Q: How do I determine what equipment to use to pump an adhesive?

A: A number of variables determine the amount of fluid pressure and type of equipment needed to dispense a viscous fluid. Viscosity, flow rate, hose length and hose diameter are the most critical variables in determining pump pressure. If you have a specific application, we recommend you consult an Application Engineer.

Q: What causes my diaphragm pump to stall?

A: An air operated diaphragm pump has a mechanism in the air motor that shifts back and forth and directs the supplied compressed air from one side of the fluid section to the other to initiate the pumping action. If the air directing mechanism gets stuck in the center or stops shifting for any reason, the pump will stall. A stalled diaphragm pump will have an equal amount of compressed air being directed to each side of the fluid section. To un-stall the pump, the shifting mechanism has to be moved off of the center of range of travel. To reduce the possibility of diaphragm pump stall, install an FRL in the compressed air supply line, and size the pump such that it cycles at least 20 times a minute.

Q: My 2 ball pump is leaking out the packing. Do I need to rebuild it?

A: Some 2 ball pumps have adjustable packing. These can be adjusted by relieving all fluid pressure from the system and tightening the packing nut or solvent cup (refer to your owner’s manual).