Transfer Pumps: Monthly Maintenance Tips

transfer pumpIt’s time to perform monthly maintenance on your plural component spray equipment. This month, we will concentrate on transfer pumps.

Here’s what to look for:

  1. Remove the air cylinder from the air motor and thoroughly clean it, as well as the air valve inside. Inspect the o-rings on the air valve for cuts, cracks or deformation that could prevent a good seal. Replace as needed.
  1. Inspect the inside of the air cylinder for scratches, wear or dents, and replace as needed. Inspect the top spring and the bottom spring for deformation or wear, and replace as needed. Note: Running out of material can cause the pump to ‘runaway’ and the springs will end up wearing down, causing them to lose their original dimension. When this happens, the air valve will not shift properly at the bottom or top of the stroke, depending on which spring is damaged. This is the major cause of transfer pumps going to the top of the stroke and not shifting or staying at the bottom of the stroke and just exhausting air. We recommend keeping a repair kit and a replacement top spring and bottom spring on hand to reduce downtime.
  1. Next, clean the old grease and any dried materials from the air motor rod and the displacement rod. Inspect both rods for any dings, scratches or wear that might prevent them from sealing properly against an oring. Replace as needed.
  1. Lubricate the air valve o-rings and cylinder with a light coat of white lithium grease and re-assemble. Remove the foot valve from the lower pump, and clean the ball and the seat. Inspect the ball and the seat for any dings, scratches or wear that might prevent them from sealing properly against one another. Replace as needed. Lubricate the foot valve threads with white lithium grease and reassemble.

After maintenance, it’s time to test the transfer pump for proper operation. The first step is to prime the transfer pump with material. When priming, you want to use the least amount of air pressure possible to make the transfer pump stroke, and the fluid must be able to leave the transfer pump outlet.

To accomplish this, begin by ensuring there is no supply air to the transfer pump and the fluid can freely exit the pump outlet either back to the drum through a return line, or through the wye strainer at the proportioner inlet by removing the wye strainer nut and screen and placing a container below it to catch the fluid. Once the return line is open or the container is in place under the wye strainer, slowly turn the air pressure up just until the pump begins to stroke. Let the pump run slowly for 20 cycles (20 up strokes and 20 down strokes).

To finish the test, close the ball valve near the wye strainer and turn the air pressure regulator up to 100 psi. Next, slowly crack the ball valve at the wye strainer until the pump starts to move upward, then close the ball valve. The pump should stop moving or “check” on the up stroke. Next, slowly crack the ball valve until the pump travels downward, then close the ball valve. The pump should stop moving or “check” on the down stroke. If the air motor shifts readily at the top and bottom of the cycle and the pump “checks” on both the up stroke and the down stroke, the transfer pump is good and is ready for production. If the air motor doesn’t change direction at the top or bottom of the cycle, the air motor needs attention. If the pump doesn’t check on the up stroke, the piston ball/seat or the piston packings are leaking fluid past them, they need to be replaced. If the pump doesn’t check on the down stroke, the foot valve ball/seat are leaking fluid past them and need to be replaced.

If you need help performing this maintenance call Intech’s team of professionals for help. We also offer a wide range of spray foam supplies and equipment. Contact us today!