Standard pressure gauges and thermometers generally cope with ambient temperatures right down to -40 �C. But what should be the top features of a mechanical measuring instrument that works perfectly well in polar climates with even lower temperatures? This can be explained using the WIKA POLARgauge� as an example. This product family has been designed specifically for measurement at extremely low ambient temperatures right down to -70 �C. The instruments are mainly utilized in crude oil and gas processing; for instance, in the local pressure and temperature monitoring of pumping stations and pipelines.
เกจวัดแรงดัน �C ? this value is frequently exceeded faster than one thinks. This is demonstrated with a turn to Russia. There, tables with standard temperature values even indicate a lot more than -60 �C for some regions. For mechanical instruments which is operated such ambient conditions, two critical points should be observed:
For pressure measurement at extremely low ambient temperatures only available with filled case: The WIKA pressure gauge model PG23LT.
1. ไดอะแฟรม filling
A measurement at extremely low ambient temperatures requires filled-filled measuring instruments. The liquids used for this protect the instrument from condensation formation within the case caused by temperature fluctuations. They thus prevent the window from frosting, so that the measured value can still be read safely.
However, nearly all silicone oils useful for this purpose commence to solidify at temperatures below -40 �C. The movement then no longer works, or may also freeze. Application-aligned tabs on the parameters (e.g. process pressure) can no longer be ensured.
Therefore, for the POLARgauge� series a particular low-temperature silicone oil has been specified. This oil remains in circumstances that enables correct measurement and measured value display, even at -70 �C.
The case of the POLARgauge� model PG23LT (r.) compared to a typical version (l.): It has no elastomers.
2. The elastomers
Elastomers are found in every mechanical pressure gauges or thermometers. They offer a secure sealing between your individual components. In detail, these are the flat gasket at the window, sufficient reason for pressure gauges additionally the blow-out device on the trunk of the case and the vent valve for pressure compensation.
However, the sealing materials found in standard designs cannot durably withstand very low ambient temperatures. They become brittle over time and lose their sealing properties. This results in the case filling escaping. This, subsequently, leads to the forming of condensation and the frosting of the window.
Therefore, in the development of the POLARgauge� series, elastomers have been eliminated in all critical points. The seal between the window and case is made of a special material. It is adapted to extremely low ambient temperatures. The vent valve has a stainless steel cap.
Overview of the WIKA POLARgauge� series
Note
You can get further information on the POLARgauge� series on the WIKA website via the next links. The product family currently comprises four instrument types: The Bourdon tube pressure gauge model PG23LT, the differential pressure gauge models 733.51, 733.31 (filled versions of the models 732.51, 732.31), the bimetal thermometer model 55 and the gas-actuated thermometer model 73. Thus, a suitable variant is available for every application. Do you want to buy differential pressure gauge models? Inside our WIKA online-shop you will find some of our standard designs. In case you have any further questions, your contact will gladly assist you to.