Diaphragm Seals Basics with Freudenberg-NOK Sealing Technologies
Diaphragm seals are an often-overlooked sealing solution that’s hidden well within your system. While you might not put much thought into these seals daily, they play an essential role in protecting the measuring instruments and gages within the system, all while allowing for proper measurement.
What are Diaphragm seals?
A diaphragm seal serves as a flexible membrane that is used to separate the measuring instrument from the media they are measuring. The main job of a diaphragm seal is to create a barrier between the fluid and the instrument itself such as a pressure gauge, or transmitter. The barrier allows for the protection of the instrument, and accurate measurement of the pressure all while preventing any fluid or contaminants from entering or exiting the system. Since the instruments or sensors are located on the other side of the seal from the fluid, diaphragms are almost always very flexible so the instruments can successfully measure the pressure. These seals are often made of some sort of flexible rubber but in some cases can be made of thin metals. Diagram seals are in direct contact with the process fluids on one side.
How do Diaphragm seals work?
Often a diaphragm seal is tightly affixed to the measuring instrument directly or by using a capillary tube. With the seal manufactured from an elastomer or metal, the diaphragm serves as a barrier, ensuring the process medium remains at a safe distance from the inner workings of the gauge. On the other side of the seal from the measuring instrument lies the system fluid. The flexibility of the seal allows for the measuring instrument to be able to accurately read the fluctuations in the process fluid to allow you to monitor your equipment and make any adjustments necessary with confidence.
Where are Diaphragm seals used?
Diaphragm seals are utilized in various industrial applications where accurate pressure measurement is essential, but the process conditions are challenging. Some common applications include:
- Chemical & petrochemical processing
- Oil & gas
- Pharmaceuticals
- Food & beverage
- Water & wastewater treatment processing
- Power generation
- HVAC & refrigeration
Freudenberg brand diaphragm seal solutions available from Gallagher Fluid Seals
With many decades of highly innovative designs and material development, our partners at FST have developed a robust portfolio of diaphragms in a variety of standard or specialized materials, all with a reliable supply chain and many certifications.
Flat Diaphragm
These are typically a flat circular shape made from an elastomer, with both sides having the same effective area to which pressure can be applied. This design is good for pumps or other applications that require regulation or control, but overall are limited in function with a shorter stroke length.
Convoluted Diaphragm
This design is similar to a flat diaphragm with the main difference it has been molded into the same shape as it will take in the application allowing it to possibly have a few indentions instead of being fully flat. This design provides a great deal of sensitivity allowing for incredibly accurate measurement.
Dished Diaphragm
Dished diaphragms are an elastomeric seal with the walls sloping inward with the ability to adjust the maximum height. Pressure can be applied from either direction for a dished diaphragm. This design is best used for actuators, regulation equipment, or measuring valves. The main downside of this design lies with difficulty withstanding high pressures due to the slope of the sidewalls.
Rolling Diaphragm
This design is similar to the dished diaphragms with a much sharper angle with a dipper dish. This design has some major advantages as it can be used for both low and high-pressure applications, can be used with any lubrication, and allows for a much smoother stroke.
Composite Diaphragm
These are used in situations where very aggressive or toxic chemicals are present. This diaphragm consists of 4 layers including a foil made from PTFE, a fabric reinforcement, an elastomeric coating, and a supporting plate.
TPU Diaphragm
TPU Diaphragms are designed with elastomers that have a high tensile strength and elasticity allowing them to ability to move more freely with a reduced chance of tears occurring. They are also capable of adding a PTFE film which allows them to be used with highly aggressive media.
DFT® Diaphragm
This is a specialized diaphragm developed by Freudenberg-NOK to solve the problem of limited possibilities for complex designs with traditional fabric diaphragms. This innovative method of producing fabric-reinforced diaphragms, by dispersing fibers within the rubber compound. Fibers dispersed within the rubber allow molding, in one press lift of complex shapes which have strength equally in all directions and planes, with improved flexibility and durability.
A more in-depth look at DFT® Diaphragms can be found in one of our previous blogs DFT Gas Meter & Regulator Diaphragms Can Be Designed Precisely (gallagherseals.com)
At Gallagher Fluid Seals, we offer you a tremendous amount of expertise with this often-overlooked category of seals. Diaphragm seals are a critical component within your system. Thanks to valuable partnerships with partners like Freudenberg-NOK, we can provide you with tremendous global resources to ensure you get the best solution to fit your unique needs. Contact your sealing experts at Gallagher today to find the right solution for you.
