The pressure pulsation damper characteristics.

  • High damping in the active frequency area, which is above 100Hz.
  • Compact sized with suitible ports for easy installation.
  • No moving parts which can be induced by wear and fatigue.
  • The damper is tested with hydraulic oil as medium
  • The damper should be installed as close as possible to pump, max 0.5m.

The history of the pulsation damper

In 1979 Hydraulik Consult AB delivered several hydraulic power units to Volvo Sweden Göteborg. At startup there was no problem with the pump noise itself since there was installed in isolated rooms within the factory. However vibrations in the very large amout of piping gave rise to a disturbing sound in the entire factory. a solution had to be found.

After a few prototyped the current TPD design was delevoped and a new product program was developed and sold to various other applications with problems of structure airborne noise from hydraulic systems.

To apply a silencer one had to determine the frequency of the fundamental tone from the pump. The pressure pulsation damper is most effective above 100Hz so therefore not only the fundamental tone will be reduced but also all the harmonics.

The size of the silencer depends on the flow rate, the working pressure and the pressure drop one will accept. usually around 2-4 bar.

Performance

Allseas

The performance by the pulsation damper is dependent of the system that it is installed in. but usually the airborne sound from the hydraulic system can be reduced with 10-25db. This is based on laboratory data and from numerous field applications.

Allseas ”solitaire”, a pipelay vessel able to lay pipes at a speed of 4-7km per day.

In solitaires pump room 5 pump sets have been installed, each pump set is operating with a pressure of 150bar and a capacity of 900 L/min.

during the tests and during operation, the silencer proved to work well. Quote Mr. Jaap Wijsman (Technical Inspector Allseas)

”We are pleased with the installation of the silencers so far. the hydraulic noise has been reduced significantly”

Hydraulic Press

APT hydraulic press

installation of hydraulic silencers at a hydraulic press.

pressure pulsations was reduced at the following main frequency and harmonics of the system.

The settling damping is the effect of installing the damper in the system ie. amplitude with silencer at each frequency corresponding to amplitude at each frequency without damper.

Frequency [Hz] Settling damping
225

450

675

900

1125

1350

25dB

35dB

10dB

25dB

25dB

25dB

Linköpings University

Test made with a Rexroth A10V 71 cc ( 80L/min ) in fluid scandinavia nr. 2 – 2000.

Comparisoin made between one-chamber and two-champer silencer and gas-accumulator type pulsation dampers.

The results shown is that the accumulator damper and the one-chamber damper tends to have higher pulsations after the damper than the two chamber type.

for both one and two chamber silencers the output pump pulsations is less than +-1 bar.