Dampers are used to protect pressure gauges from pressure surges and pulsations.
The dampers operate on the principle of slow flow of the medium (filling) through a narrow orifice (cataract) or, alternatively, through a labyrinth formed by slits and holes. Their disadvantage is that, to be effective, the orifices must be very narrow, and over time they may become blocked by impurities from the process. A further disadvantage is that their effectiveness varies drastically depending on whether the medium is a gas (air) or whether the damper is flooded with liquid. A typical sign of damage caused by pulsating pressure is a broken pressure gauge pointer; this is a fatigue fracture.
A solution that eliminates both disadvantages is a combination of a diaphragm separator and a cataract, i.e. a very narrow channel (‘nozzle’). The orifice can be very narrow, as it is located in a separate part of the system and the process medium cannot reach it. The working fluid is silicone oil or another suitable high-viscosity fluid. The viscosity of silicone oil varies only slightly with temperature, so the damper maintains constant efficiency over a wide range of operating temperatures.
One option is therefore to install a Type W separator with a built-in damper upstream of the pressure gauge.
The pressure gauge can also be protected against shocks and vibrations by filling the pressure gauge housing with a damping fluid (glycerine). However, this protection is not suitable where pulsations and pressure surges are the main destructive factors. This is because the maximum damping effect occurs at the end of the pointer, where the movement is fastest.
An even more effective way of protecting against shocks and vibrations is to connect the pressure gauge via a capillary tube and position it away from the vibrating equipment, for example on a building wall. A diaphragm seal is fitted at the start of the capillary tube. This can be a flanged type (type P), but there are also a number of other designs to choose from. The advantage is that the capillary tube isolates the pressure gauge not only from vibrations and shaking, but also from pulsations and pressure surges.
Videos demonstrating a comparison of pressure gauge damping methods:
- Pressure gauge without damping
- Glycerine-filled pressure gauge
- Pressure gauge with a separator and a throttle nozzle
- Comparison of a non-damped pressure gauge and a glycerine manometer
- Comparison of a non-damped presure guage and pressure gauge damping with a separator and a throttle nozzle
- Comparison of the damping characteristics of a glycerine pressure gauge and a pressure gauge with a separator and a throttle nozzle
