Building Services Engineering and Refrigeration Engineering

Pressure measurement in refrigeration engineering

Bourdon tube pressure gauges for pressure measurement in large-scale refrigeration plants (AppBe_K_022)

for manufacturers of large-scale refrigeration plants
Fields of application Pressure measurement in refrigeration engineering Armaturenbau Manotherm
A refrigeration plant is for refrigeration. This means that via a process, heat is withdrawn at a point that is to be refrigerated, and emitted to the atmosphere at another point. This is a complex circuit, as all components of the refrigeration plant have to be synchronised. The reliability of such a plant must be ensured, as possibly emerging refrigerant would pollute the environment. Therefore, pressure measuring instruments also have to meet high demands.

The problem:

The pressure test in a refrigeration plant is to ensure that the system withstands the operational pressure loads. It is important that the system is leak-tight and that no refrigerant can escape. On the one hand, leaks cause a drop in the refrigerating capacity of the plant and on the other hand, they can cause environmental pollution, as refrigerants contain fluorine or chlorine.

In order to prevent such "dangers", the instruments have to withstand the strong vibrations of the plant. Furthermore, the pulsation of the medium must be reduced.

Our solution:

Our instruments are filled with glycerin. That way, strong vibrations can be reduced. Refrigeration pumps cause pulsations (of the medium) in the tubing and thus dynamic loads at the pressure gauges. A restrictor screw with a small orifice in the inlet port of the pressure gauge "calms" the pulsations and consequently the pointer movement. The durability of the pressure gauges is thus significantly prolonged.

For this application, one pressure gauge for the low-pressure side (blue case) and one pressure gauge for the high-pressure side (red case) is used.

Our instruments in detail:

For the right temperature: Bourdon tube pressure gauge RChgG 80 – 1
Bourdon tube pressure gauge RChgG 80 – 1 Low-pressure side: case blue -1-16 bar Armaturenbau Manotherm
Low-pressure side: case blue
  • Pressure range*: -1 / +16 bar
  • With temperature scale acc. to refrigerant (e.g.: R 134 A, R 404 A, R 407 C, R 507, R 744)
  • Process connection: 7/16"-20 UNF bottom
  • Restrictor screw Ms with orifice 0.3 mm
  • Mounting of the instrument: 2 blind rivet nuts M4, 10 mm deep, 60 mm distance in back of case

* other pressure ranges upon request

Bourdon tube pressure gauge RChgG 80 – 1 High-pressure side: case red Armaturenbau Manotherm
High-pressure side: case red
  • Pressure range*: -1 / +28 bar
  • Else as low-pressure