Liquid-filled pressure gauges are used in applications involving high dynamic shock and vibration loads. The filling fluid dampens the vibrations that occur, thereby reducing the load on the gauge's mechanical parts.
Use of filling fluid
Depending on the operating conditions, glycerol-water mixtures or silicone oils are the most commonly used filling fluids. Glycerin water is suitable for most applications and ambient temperatures. Especially for low pressure ranges, it makes sense to use it because of the low density of the liquid and the associated low resistance on the pressure element. When pressure gauges are exposed to extremely high (> +60 °C) or very low (< -20 °C) temperatures, silicone oils are primarily relied upon.
The housing of the pressure gauge is not fully filled because, depending on humidity and ambient temperature, the filling medium absorbs additional water and expands accordingly. To provide enough room for this expansion and to prevent leaks in the case, by default the case is only filled to 80% - 90%.
Advantages of filling liquids
The filling fluid dampens any pressure peaks, shocks and vibrations that occur and protects the mechanics of the pressure gauge. Thus, material fatigue and failure are counteracted.
Another decisive factor for the user is ensuring the readability of the main pressure. The filling fluid restricts the movement of the pointer even under severe vibration loads. Without liquid damping, the needle would not show the actual applied pressure, but would instead move back and forth according to the vibration frequencies prevalent in the application. In the case of resonance, even deflection angles of more than 180° are possible.
in conclusion
Liquid-filled pressure gauges are suitable for a variety of applications, especially processes involving shock and vibration.
