A capsule pressure gauge is a type of pressure gauge that utilizes a diaphragm or capsule as its sensing element. The capsule is typically a thin, flexible membrane made of metal, usually stainless steel or brass, which deforms in response to changes in pressure. This deformation is then converted into a mechanical displacement, which is indicated on a dial or display to provide a pressure reading.

Here’s how capsule pressure gauges typically work:

1. Pressure Sensing: The capsule is exposed to the pressure being measured. As the pressure changes, the capsule expands or contracts, causing it to deform.

2. Mechanical Linkage: The deformation of the capsule is mechanically linked to a pointer or other indicating mechanism.

3. Dial Display: The mechanical displacement of the capsule is translated into a pressure reading on a dial or display, calibrated in the appropriate units (such as psi, bar, kPa, etc.).

Capsule pressure gauges offer several advantages:

• Sensitive: They are highly sensitive to small changes in pressure due to the flexibility of the capsule.
• Compact Design: Capsule gauges are often compact in size, making them suitable for applications with space constraints.
• Low Pressure Measurement: They can measure low pressures accurately due to their sensitivity.
• Resistance to Vibration: Capsule gauges are less susceptible to damage from vibration compared to some other types of pressure gauges.

However, there are also limitations to consider:

• Limited Pressure Range: Capsule gauges are typically limited to measuring relatively low pressures.
• Temperature Sensitivity: Extreme temperatures can affect the accuracy of the gauge, as they can cause the material of the capsule to expand or contract.
• Susceptibility to Overpressure: Capsule gauges are more prone to damage from overpressure compared to other types of pressure gauges.

Capsule pressure gauges find applications in various industries, including HVAC systems, medical equipment, laboratory instruments, and process control where accurate measurement of low to moderate pressures is required. They are particularly well-suited for applications where sensitivity and compactness are important considerations.