Use a heating tape with the high-temperature silicone oil of the transmitter in low-temperature conditions
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Since winter is approaching, our company has required that heat tracing be added to the capillaries of transmitters that use high-temperature silicone oil. I would like to know what the disadvantages are of using high-temperature silicone oil in low-temperature environments (the temperature here in winter is around -10 degrees). Is it necessary to use heat tracing? What temperature should the heat tracing reach, and should a constant-temperature type of heat tracing be used?
There is a specific temperature range for filling at high temperatures; theoretically, the device can function properly within this range. Temperatures that are too low or too high will affect the measurement results. Check it out – just determine the temperature range for filling the liquid, and then select an appropriate temperature for the heating element. Additionally, Rosemount now offers an electronic remote transmission product that does not use capillaries; instead, it relies on cables for connection, which helps to avoid the effects of temperature as well as issues related to insulation and heating. Moreover, compared to the previous dual remote transmission systems, in the case of an issue with one end of the electronic remote transmission system, that part can be replaced separately, something that was not possible with the earlier systems
Low temperature, high viscosity, and slow response. Extreme, silicone oil crystallization. Use a self-regulating temperature controller; the temperature should be maintained at around 25 degrees, as indicated in the manufacturer’s specifications. High-temperature synthetic oils are mostly DOW CORNING products. @jiaguoyun
The pressure transmission performance of high-temperature silicone oils is affected in low-temperature environments. For example, during the winter months in the north when temperatures drop below zero, if high-temperature capillaries are exposed to the atmosphere, the silicone oil will condense. In the absence of proper insulation and heating measures, the silicone oil in the capillaries can be affected by low temperatures, leading to measurement errors. Therefore, it is necessary to implement adequate insulation and heating measures, while also preventing direct contact between the capillaries and the heating source~~
-10 degrees is not low either; a constant-power model will suffice, and an automatically temperature-controlled one is of course better~~
The operating temperature range for DC704 silicone oil is 0~315°C, while that for DC705 silicone oil is 20~350°C. At low temperatures, high-temperature silicone oils have high viscosity and may even solidify, resulting in a slow response time of the transmitter or its inability to function.
Thank you all for the explanations. I used to think it couldn’t be used at low temperatures because low temperatures affect the density of silicone oil; it seems I was wrong.
You can set a response time that is acceptable to you, then contact the manufacturer to determine whether it is possible to use it. As far as I know, many manufacturers use the freezing point of the filling oil as the minimum operating temperature; at such temperatures, it is simply impossible to read the pressure.
It is necessary to determine whether heating is required, and whether it can be used at -10°C; it is necessary to check specifically what the minimum operating temperature for this high-temperature silicone oil is. Under normal circumstances, the lower limit for high-temperature silicone oil is 0 degrees, but this is not absolute. If heat tracing is required, a self-regulating type is recommended as it is convenient for both installation and maintenance.