The difference between a diaphragm pressure gauge and an ordinary pressure gauge

Differences in structural design

The core of the ordinary pressure gauge is the Bourdon tube measuring system, when the medium directly enters the curved metal pipe, the pressure deforms the tube body and drives the pointer to rotate. This open design is like an unprotected sensor that is directly exposed to the medium.

The diaphragm pressure gauge builds a double defense system: the elastic diaphragm acts as the first line of defense, isolating the corrosive medium in the sealed chamber; The filling fluid (silicone oil or fluorine oil) acts as a pressure transfer medium and transmits the deformation to the Bourdon tube system via a capillary. This isolation design is like putting a chemical mask on the pressure gauge, allowing it to work accurately in highly toxic and highly corrosive scenarios.

The ability of the medium to adapt

Ordinary pressure gauges are only suitable for measuring clean, low-viscosity neutral media (e.g. air, water, lubricating oil, etc.). Its performance deteriorates dramatically when encountered:

1. Crystallization medium (such as caustic soda solution): the crystalline material blocks the spring tube

2. High viscosity fluids (e.g. bitumen): The damping effect causes the pointer to get stuck

3. Media containing solid particles (such as slurry): wear measuring mechanism

Diaphragm pressure gauge can adapt to the following media:

1. Anti-corrosion type: Hastelloy diaphragm is used to deal with strong acids and alkalis

2. Hygienic type: electrolytic polishing surface treatment meets pharmaceutical GMP standards

3. High temperature type: graphite filler can withstand 400°C medium temperature

Comparison of dimensions to measure performance

The advantage of a common pressure gauge is its fast response, and its direct-contact design allows for almost zero delay in pressure transmission, which is excellent in compressed air systems where real-time monitoring is required. However, the range is usually limited to -0.1~100MPa, and the overload capacity is weak.

Diaphragm pressure gauges achieve a breakthrough in range with an isolation system:

1. Micro pressure measurement: 0.1kPa level pressure can be detected (such as clean room differential pressure monitoring)

2. Ultra-high pressure measurement: special structure design up to 1000MPa

3. Negative pressure measurement: better stability in vacuum environment

Intelligent transformation path

1. Ordinary pressure gauges mostly use external sensors to achieve digitization, but they are subject to structural limitations

2. Diaphragm pressure gauge can integrate temperature/pressure composite sensor with the advantage of isolation chamber