دیافراگم سیل – Diaphragm Seal

What is a Diaphragm Seal? 

Chemical seals, or diaphragm seals, are used for fluids with high viscosity and corrosiveness.

These devices are used to prevent direct contact between the measured fluid and the measuring instrument.

These sensors, typically made of metal or specific types of flexible polymers, are constructed as either a flat or corrugated diaphragm.

One of the main advantages of diaphragm seals is their ability to protect other pressure-measuring instruments from harsh conditions, such as high temperatures and corrosive fluids, as well as their excellent sealing capability.

In other words, these types of sensors require significantly less additional sealing equipment.

For this reason, many pressure-measuring instruments use a diaphragm as the pressure sensor.

These devices use either the displacement of the diaphragm seal or the strain of its surface to perform measurements.

For example, capacitive, inductive, resistive, and piezoelectric transducers utilize the displacement created by the diaphragm.

They are used to measure pressure changes, while strain gauge transducers utilize the surface strain of the diaphragm.

Diaphragm Pressure Gauges

These sensors, typically made of metal or specific types of flexible polymers, are constructed as either a flat or corrugated diaphragm.

These types of devices are primarily used for measuring differential pressure.

In a differential pressure (DP) cell, the mechanical deformation of the diaphragm causes a small displacement as well as surface strain of the diaphragm.

These two properties—displacement and surface strain—can be used independently to measure the applied differential pressure.

In fact, the amount of strain and displacement generated has a specific relationship with the applied differential pressure.

Therefore, by knowing one of the two pressures, the unknown pressure can be determined.

Diaphragm Pressure Sensor

One of the main advantages of diaphragm seals is their ability to protect other pressure-measuring instruments from harsh conditions, such as high temperatures and corrosive fluids, as well as their excellent sealing capability.

In other words, these types of sensors require significantly less additional sealing equipment.

For this reason, many pressure-measuring instruments use a diaphragm seal as the pressure sensor.

These devices use either the displacement of the diaphragm or the surface strain of the diaphragm for measurement.

For example, capacitive, inductive, resistive, and piezoelectric transducers utilize the displacement created by the diaphragm.

They are used to measure pressure changes, while strain gauge transducers utilize the surface strain of the diaphragm.

Diaphragm Pressure Transmitter

 Since many non-metallic diaphragms are sensitive to corrosive substances and impact, two diaphragms are used in such cases.

The first diaphragm, which is in contact with the fluid, is usually made of stainless steel.

The deformation of the first diaphragm under the influence of the fluid pressure causes the displacement of an intermediate fluid, which is incompressible and non-corrosive.

Silicone oil, which also absorbs shocks and vibrations, is typically used as the transmitting fluid.

This fluid transmits the pressure to the second diaphragm, which is typically non-metallic.

Diaphragm Seal

Since diaphragms must be installed under specific conditions, such as being mounted between two flanges, replacing and calibrating them can be challenging.

For this reason, in many cases, a capsule containing two connected metal diaphragms is used.

This capsule is connected to the measured fluid through a tube.

When the process fluid enters the capsule, it applies pressure to the capsule walls, causing deformation of the diaphragm walls.

Capsules can also be arranged sequentially in line, thereby increasing the resulting displacement.

 Compared to Bourdon sensors, diaphragm sensors, having a larger support surface, are less sensitive to environmental vibrations.

These sensors are also widely used for measuring the pressure of viscous fluids.

It is worth noting that a major drawback of diaphragms is zero-point adjustment.

دیافراگم سیل، اشکرافت دیافراگم سیل چیست، دیافراگم سیل رویگر ،ساخت دیافراگم سیل، قیمت دیراگم سیل ،کاربرد دیافراگم سیل