Diaphragm Seal Systems in Pressure Measurement and Types

Pressure transmitter with Diaphragm Seal

What is a diaphragm seal?

A diaphragm seal is a sealing device used to prevent fluid leakage, usually composed of a diaphragm, bolts, gaskets and other components. Its main function is to isolate two different media to prevent them from mixing or leaking.

The working principle of a diaphragm seal is to use the elasticity of the diaphragm to achieve sealing. When the medium pressure acts on the diaphragm, the diaphragm is deformed by force. Thus, the two media are isolated and prevented from crossing each other.

Diaphragm seal systems are usually installed with pressure gauges, pressure switches, and pressure transmitters.

These seals are very important because they help isolate the pressure sensor from the contents that may be toxic, reactive or irritating chemicals. In this article, we will discuss the details of diaphragm seals and their various types.

Structural composition of diaphragm seals

Generally speaking, diaphragm seals include diaphragms, middle bolts, middle gaskets, plug plates, anchor bolts, anchor gaskets, etc.

Among them, the diaphragm is the key component of the isolation medium, and is usually made of rubber, fluoroplastics, polytetrafluoroethylene and other materials. To ensure its corrosion resistance, high temperature resistance and pressure resistance.

Types of Diaphragm Seals System

Diaphragm seals are usually made of 316 stainless steel, Teflon, Hastelloy, Inconel, etc. The requirements of diaphragm seals vary for each industrial application. They can be customized according to your requirements. Here are some common types of diaphragm seals:

These seals are mounted on transmitters, meters or switches, depending on the application. They are connected via threaded connections or flexible capillaries. Threaded diaphragm seals are compact in design and can be installed in smaller areas.

Most manufacturers offer a lot of options to the user. Such as replaceable lower parts, cleaning rings or various materials for wetted parts. The diaphragm can be welded internally or made completely of stainless steel.

These seals are placed internally using various types of connectors. They come in various sizes and promote laminar flow of the fluid.

In-line seals are placed in a way that prevents bacterial growth or other buildup that may occur on the diaphragm over a period of time. They also help eliminate errors that may occur while operating the diaphragm.

These seals are used where a great deal of hygiene is required, such as in food processing units or medical research laboratories.

These diaphragm seals must comply with FDA requirements and Clean-in-Place (CIP) methods. They help eliminate any risk of bacterial growth or contamination.

These seals are mounted directly on instruments, transmitters, pipes, etc. Depending on the application and process fluid, the diaphragm is available in a variety of materials.

Since it can be mounted directly, application compatibility is an important factor when choosing this type of seal.

Benefits of using diaphragm seals on pressure measurement

It is worth investing in diaphragm seals, which can effectively control costs. And ensure the safety of users. In addition to the obvious advantage of isolating the instrument from the contents. Here are some other advantages of diaphragm seals:

Helps prevent liquid clogging and crystallization;
Eliminates the risk of corrosion or any reaction of fluids with these mainly metal devices;
Enables the instrument to operate normally in a wide temperature range and in a variety of toxic liquids and semi-solids;
Helps extend the service life of closed instruments;
Available in all standard sizes and nominal diameters;
All wetted parts can be made of special materials selected by the user;
Rugged and durable, fully welded design;

Diaphragm seal pressure transmitters are suitable for the following working conditions:

The high temperature medium needs to be isolated from the transmitter.
The measured medium has a corrosive effect on the sensitive elements of the transmitter.
Suspended liquid or high viscosity medium.
The measured medium solidifies or crystallizes due to changes in ambient or process temperature.
Replacing the measured medium requires strict purification of the measuring head.
The measuring head must be kept clean and hygienic.
Sealed pressure vessel level measurement.