I recently made a change that substantially reduced the noise generated by my Ulka vibe pump. It was a real surprise to me so I thought I'd share the experience so others can do the same.

I had used a float valve in the reservoir in my VBM DD. Recently, I had a couple of times that there were leaks from the reservoir so I wanted to make a change. I bought the direct-connect kit from Chris Coffee that includes a solenoid. I installed it according to instructions and suspended the solenoid using Ulka pump rubber mounts.

The pump used to be quite noisy when turned on until the point where it hit max OPV pressure. Now, the sound made by the pump is about the same volume when it's ramping up pressure as when it is pumping at OPV pressure.

I think it's because there is always steady input pressure on the vibe pump. It really made a huge difference.

Curtis,
You are correct. The vibe pump nose is in direct proportion to the pressure on the outlet end of the pump. The reason for this is the travel, or stroke, of the piston. When the pressure is low the stroke of the pump is longer. As pressure builds the stroke decreases. The stroke decreases because the outlet pressure is stopping the piston sooner than with decreased pressure (this assumes there is constant power coming from the coil, there are some slight changes but are negligible). When you apply line pressure, the outlet of the pump at a minimum is at line pressure.

BillC