One of the biggest challenges for pressure instruments is dealing with elevated process temperatures. Pressure transmitters often cannot withstand process temperatures above 120°C. Similar, bourdon tube pressure gauges (non-liquid filled) can withstand a temperature of 200°C for a short period of time. Hence, these instruments need to be protected and the process temperature needs to be brought down to temperatures that are within the allowable limits of the instrument itself and comply with a safe work environment. The actual warming from process medium to the temperature at the measuring sensing element depends on many factors, such as mounting position, ambient conditions (temperature, wind and radiation), materials and many more.
Therefore, it is recommended to always bring the process temperature back to 100°C or less. There are several cooling devices available to lower the process temperature. Always in combination with a diaphragm seal and a compatible filling fluid. The series of cooling devices are following and can be assembled in combination with most diaphragm seal types:
• Direct mount nipple with a temperature reduction of approx. 50°
• Extended direct mount nipple 80mm with a temperature reduction of approx. 100°
• Extended direct mount nipple 150mm with a temperature reduction of approx. 175°
• Temperature reducer with a temperature reduction of approx. 250°
• Remote mounting with capillary with a temperature reduction of minimum 300°C.
If your process is not prone to clogging and is considered very clean, it may be possible to ensure cooling with just a needle valve or extension. However, with a small opening of only 1mm or 2mm there still exists a reasonable chance of clogging. That is why Badotherm always recommends the usage of diaphragm seals.