Description
The Capsule Diaphragm Gauge is a precision low-pressure mechanical pressure gauge specifically designed for measuring dry, non-corrosive gases, air, vacuum, and low differential pressures. Unlike Bourdon tube pressure gauges that are intended for medium and high-pressure applications, this instrument uses a corrugated metallic capsule formed by joining two thin diaphragms around their circumference. The capsule expands and contracts with very small pressure changes, providing the sensitivity required for accurate measurement in low-pressure systems where conventional pressure gauges cannot achieve sufficient resolution.
Key Features
- Sensing Element: Corrugated metallic capsule (brass or SS 316) for ultra-low pressure sensitivity
- Pressure Range: 0–2.5 mbar to 0–600 mbar (0.025 to 6 kPa)
- Negative ranges (vacuum) and differential pressure models available
- Dial Size: 100 mm, 160 mm for high legibility
- Accuracy: ±1.6% FSD (EN 837-2 Class 2.5 available)
- Wetted Parts: Brass (standard), SS 316 (for aggressive/moist gases)
- Process Connection: ¼” BSP / NPT bottom or back entry
- Temperature Compensation: Bi-metallic strip for ambient temperature correction
- Suitable for dry non-corrosive gas and air measurement only
- Rotary movement with precision-machined brass gearing
- Large clearly marked scale divisions for field readability
- Zero adjust screw accessible without gauge removal
- Custom scale ranges and dual-scale options available on order
Applications
- Natural gas (PNG) distribution and city gas pressure monitoring
- Gas burner and combustion air pressure control in furnaces and kilns
- HVAC duct static pressure measurement and system balancing
- Clean room differential pressure monitoring (positive/negative pressure)
- Biogas and digester gas pressure measurement
- Filter differential pressure monitoring in air handling units
- Gas chromatography and laboratory low-pressure systems
- Draught measurement in chimneys, flues, and stack systems
- Medical gas manifold pressure indication
- Laminar flow hoods and pharmaceutical isolators
Datasheet
FAQs
1. What is a Capsule Diaphragm Gauge?
A Capsule Diaphragm Gauge is a low-pressure mechanical pressure gauge that uses a corrugated metallic capsule to accurately measure low positive pressure, vacuum, and differential pressure in dry, non-corrosive gases and air. It is commonly used where precise measurement of very low pressures is required.
2. How does a Capsule Diaphragm Gauge work?
The gauge contains two thin corrugated metallic diaphragms joined together to form a sealed capsule. As the applied pressure changes, the capsule expands or contracts. This mechanical movement is transferred through a linkage mechanism to the pointer, which indicates the corresponding pressure on the calibrated dial.
3. What pressure range does this model measure?
This model measures pressures up to 1000 mmWC (millimetres of water column). Aavad Instrument Pvt. Ltd. also offers custom low-pressure ranges to suit specific applications involving low-pressure gas, air, vacuum, and differential pressure measurement.
4. Can this Gauge measure Liquids?
No. A Capsule Diaphragm Gauge is designed exclusively for measuring dry, non-corrosive gases and air. It is not suitable for liquids, slurry, viscous media, steam, or corrosive chemicals, as these media can damage the capsule element and affect measurement accuracy.
