What is the difference between liquid filled and air filled pressure gauges?

The primary difference between liquid-filled and air-filled pressure gauges lies in the filling medium used to dampen and protect the internal components of the gauge. This choice of filling medium can influence the gauge’s performance, accuracy, and suitability for specific applications.

Liquid-Filled Pressure Gauges

Liquid-filled pressure gauges are filled with a specialized liquid, often a glycerin-based solution, that is sealed within the gauge casing. The liquid serves several purposes:

Dampening

The liquid helps dampen vibrations and oscillations caused by pressure fluctuations or mechanical vibrations. This reduces the pointer’s movement, making it easier to read the pressure accurately.

Lubrication

The liquid provides lubrication to the internal components, contributing to the gauge’s longevity and smooth operation.

Temperature Compensation

The liquid can help compensate for temperature variations, ensuring that the gauge remains accurate in different temperature conditions.

Protection

The liquid-filled design helps protect the internal components of the gauge from external elements like dirt, moisture, and corrosive agents.

Liquid-filled pressure gauges are commonly used in industrial applications where there are significant vibrations or pulsations, as well as in outdoor environments or applications involving corrosive substances.

Air-Filled Pressure Gauges

Air-filled pressure gauges, as the name suggests, are filled with air or a non-corrosive gas. They lack the damping and lubrication advantages of liquid-filled gauges but have their own benefits:

Cost and Simplicity

Air-filled gauges are generally simpler and less expensive to manufacture because they lack the liquid and associated components.

Cleanliness

Air-filled gauges do not have the risk of leakage associated with liquid-filled gauges. This can be important in certain clean environments.

Specific Applications

Air-filled gauges might be preferred in applications where the presence of liquid could pose a contamination risk, such as in some food processing or pharmaceutical industries.

Ultimately, the choice between a liquid-filled and an air-filled pressure gauge depends on the specific needs of the application. Liquid-filled gauges are often favored in industrial settings with heavy vibrations, while air-filled gauges are used when simplicity and cleanliness are priorities.