Why do pressure gauges have liquid in them?

Why do pressure gauges have liquid in them?

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Pressure gauges often use liquid-filled casings for specific applications and benefits. Here are some reasons why pressure gauges may be filled with liquid:

  1. Damping Vibration and Pulsation: Liquid-filled gauges help dampen the effects of vibration and pulsation in the pressure system. The liquid absorbs these fluctuations, preventing rapid needle movements and providing a more stable and accurate reading.

  2. Enhanced Durability: The liquid filling can protect the internal components of the gauge, such as the Bourdon tube or diaphragm, from damage due to harsh environments or shock. This can extend the lifespan of the gauge and improve its reliability.

  3. Temperature Compensation: The liquid inside the gauge can also help compensate for temperature variations. It ensures that the gauge remains accurate even when the temperature of the measured medium or the environment changes.

  4. Lubrication: The liquid acts as a lubricant for the moving parts within the gauge, reducing friction and wear. This can contribute to the long-term reliability and performance of the gauge.

  5. Corrosion Resistance: Some liquid-filled gauges use glycerin or other solutions that provide a protective barrier against corrosion, which can be especially beneficial in corrosive or aggressive environments.

  6. Sealing and Leak Prevention: The liquid filling helps seal the internal components, reducing the risk of leaks and ingress of contaminants. This is important for maintaining the accuracy and integrity of the gauge.

  7. Readability: The liquid can improve the readability of the gauge by reducing glare and minimizing parallax errors. This is particularly useful in situations where accurate readings are crucial.

Common liquids used in pressure gauges include glycerin, silicone oil, or other suitable fluids. It's important to choose a liquid that is compatible with the gauge's construction materials and the specific conditions of use.

While liquid-filled gauges offer these advantages, there are also dry gauges that do not contain liquid. The choice between liquid-filled and dry gauges depends on the application requirements and environmental conditions.