Question about capillary pressure switch
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Will the silicone oil in the capillary expand? We have a capillary pressure switch here. It keeps giving false alarms these days. It is normal to remove it and check it. I would like to ask everyone, will the silicone oil expand when heated? This is a high-alert pressure switch.
It depends on your usage conditions, what kind of product, and the parameters of a certain foreign brand.: warm pack: 0.15% of indication range per °C change in ambient temperature capillary: 0.03% of indication range per °C change in ambient temperature
I just made a mistake, the above are the parameters of the capillary thermometer, look at this: Operating temperature range Medium: Tmax = +60 °C Ambient: Tmin = -20 °C Tmax = +60 °C Temperature performance Indication error when the temperature of the measuring element deviates from 20 °C: rising temp. approx. ±0.4 %/10K falling temp. approx. ±0.4 %/10K percentage of full scale value is closely related to temperature
Silicone oil will expand when heated, but not too much and will not have such a big impact
The ambient temperature has an impact on the capillary tube, especially when there is a heat source nearby, the impact will be greater.
The key depends on which product it is. Generally, the cause of false alarms is loose contacts. Mechanical vibration can cause false alarms. The old poster uses a capillary diaphragm pressure switch. What is the actual operating temperature? If it's below 200° or 250°, it's generally fine unless the set point value is very small. In addition, the length of the capillary tube also depends on the length. If it is too long, false alarms may easily occur in the presence of mechanical vibration. In addition, if it is a vertical pipeline, when the pump suddenly stops, the pressure on the switch is sometimes higher than the maximum pressure of the pump. (Detailed analysis of specific situations)
The thermal expansion of silicone oil is very small and will not affect it. It may be caused by pulse pressure.