Vacuum & Capsule Gauges

Vacuum and capsule gauges use a thin, corrugated capsule sensing element — typically formed from two welded metal diaphragms — that flexes in response to changes in pressure. Unlike Bourdon tube gauges designed for higher pressures, the capsule element is optimised for vacuum and low positive pressure ranges, delivering exceptional sensitivity and accuracy across the measurement span. As pressure changes, the capsule expands or contracts, transmitting mechanical movement through a precision linkage to the pointer on the dial face.

These gauges are widely used across HVAC systems, refrigeration circuits, and general process applications where accurate monitoring of vacuum or low positive pressure is critical. In HVAC and refrigeration, they are commonly installed on suction lines, vacuum pump outlets, and low-pressure vessels to verify system integrity and detect leaks. In process environments, they support quality control and safety monitoring wherever precise low-pressure readings are required.

Case materials are available in stainless steel or ABS plastic to suit different environmental and budgetary requirements. Stainless steel cases offer superior corrosion resistance and mechanical durability, making them the preferred choice for demanding industrial or outdoor installations. ABS cases provide a cost-effective alternative for lighter-duty or indoor applications. A glycerin-filled option is available for both case types, dampening pointer oscillation caused by vibration or pulsating pressure, which extends service life and improves readability in dynamic operating conditions.

Dial sizes range from 40 mm to 160 mm, allowing selection based on readability requirements and available panel or pipe space. All models feature a dual-scale dial displaying both vacuum (negative pressure) and low positive pressure readings simultaneously, eliminating the need for separate instruments when monitoring across the zero-pressure boundary. Scales are clearly graduated and easy to read at a glance, supporting safe and efficient system operation.

Installation is straightforward via standard bottom or back process connections. For glycerin-filled units, ensure the gauge is mounted in the correct orientation to prevent fluid migration. Periodic inspection of the dial face, pointer, and case seal is recommended to maintain measurement integrity. In dry-fill gauges used in high-vibration environments, consider retrofitting with glycerin or a snubber to protect the capsule element and extend calibration intervals.