The heating issue of diaphragm pressure gauges
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Does the diaphragm pressure transmitter on the water scrubber also require heating? I see that the specification mentions high-viscosity silicone oil (operating at -10~200°C). In the outdoor conditions of the north, where temperatures can drop below -10°C, will the high-viscosity silicone oil freeze? So is it necessary to install heat tracing? If it is ordinary low-pressure steam, will there be enough pressure to push the steam to the heat spill point?
1. Ignore the silicone oil; focus on the operating temperature requirements of the transmitter. If those requirements cannot be met, insulation or heating measures must be taken. 2. Check the temperature at the diaphragm flange of the transmitter in winter, as well as the distance between the transmitter and the diaphragm flange. If heating can be achieved by the temperature of the equipment medium, insulation in winter is sufficient; otherwise, heat tracing is required.
If needed, the market has insulation boxes for such instruments.
May I ask if other media can be used besides silicone oil? For example, if the ambient temperature is -30°C, but the freezing point of the medium inside is below -30°C, does that mean heating is not necessary? (Assuming the pressure tapping flange connection is very short and has already been insulated as part of the overall exterior insulation of the equipment)
Silicone oils are a type of synthetic substance; it is possible to adjust their properties such as operating temperature, viscosity, lubricity, aging resistance, insulation, and wetting capacity according to specific requirements. So there are many models to choose from. Silicone oil is chosen for instruments mainly due to its stability, as it does not deteriorate easily under various conditions. Theoretically, it is possible to use other media for filling, but few of them can meet the requirements (for example, fluorinated oils can allow instruments to come into contact with media at temperatures above 250°C). In addition to not deteriorating, instrument filling fluids must also not vaporize, cannot be compressed, and their coefficient of thermal expansion must not be too high, among other requirements.