Liquid-filled pressure gauges are filled with liquid, usually glycerin or silicone oil, and are designed to perform best under adverse conditions. There is oil in some pressure gauges, but some do not. Is there any difference between these? What does the “oil” in the pressure gauge do?
In actual situations, the resistance increases after the pressure gauge is filled with oil. So the pointer will be more stable, which can prevent the hands from shaking. This kind of gauge is what we often call shockproof pressure gauge. We generally use it in harsh environments (such as a noisy environment) or when the pressure fluctuations in the system are large (such as a plunger pump). The oil makes the pressure gauge reading accurate and prolongs its service life.
What kind of oil is in a pressure gauge? Among them, the “oil” is mainly glycerin and silicone oil. The effects of the two oils are not the same. Glycerin mainly plays a role in shock resistance; silicone oil can also play a role in shock resistance, but silicone oil is more resistant to low temperatures than glycerin. If the outdoor temperature reaches minus 20°C, glycerin will crystallize, But silicone oil can also make the pressure gauge work normally.
Therefore, both glycerin and silicone oils can be used, but at least two points should be considered when making specific choices: 1. Thermal expansion coefficient, the smaller the coefficient, the better, this is mainly affected by temperature; 2. Application occasions In the food industry, neither of these two oils can be used. In case the diaphragm is damaged, the oil will contaminate the food. It is also not recommended to measure strong oxidants, otherwise it will cause an explosion.