Diaphragm Material Selection
For more than 60 years, MPS Melt Pressure Sensors have been used in various applications around the world.
For over 60 years, melt pressure sensors have been used in various applications around the world. MPS, the original patent holder for the melt pressure sensor used in extrusion, continues its investments worldwide to meet the ever-changing demands of the plastic market.
The choice of diaphragm material used in the MPS melt pressure sensor depends on the application in which the melt pressure sensor will be used. We have to ask the question first, does the melt pressure sensor come in contact with a pure material or a mixture of materials? Next, we will consider the properties of these materials based on the classification of each polymer component.
The classification of polymers are thermoplastics, elastomers, thermoplastic elastomers and thermosets. Various polymer families within these classifications are Polyolefins, Polyesters, Urethanes and Amides.
It includes methods such as thermoplastic and elastomer processing, extrusion, injection molding and compression molding. All of them use pressure sensors to provide pressure measurement and control in these processes.
MPS pressure sensors are designed to provide years of reliable service provided that the right qualities are suited to withstand these environments.
Is the material Sticky? Corrosive? What are Process Temperatures?
For example: If the application uses polypropylene, MPS will suggest our standard diaphragm option on the selected pressure sensor.
Our standard diaphragm is Dymax ® coated stainless steel (15-5PH), which stands well against the flow of abrasive materials and is reliable in most extrusion environments.
If the process application requires material to adhere to our standard diaphragm, such as an elastomer (TPE), we can suggest a titanium nitrite coating (TiN) to prevent this adhesion or limit the material's ability to deform the diaphragm.
Other applications may use materials such as polymers with corrosive properties, fluoropolymers (PTFE or FEP) that our standard diaphragm will not last for a long time due to oxidation. MPS may suggest using a different diaphragm material such as Inconel or Hastelloy.
Materials and coatings that can be used in diaphragm selection:
15-5 PH Dymax ® coated stainless steel - Provides durability with wear resistance as standard in most sensor models.
Hastelloy - It is not recommended to use for a long time at high temperatures, it provides corrosion resistance.
Inconel 718 - provides abrasion and corrosion resistance, recommended for use at 750 degrees F or higher.
Dymax ® - Durable, proprietary surface coating, abrasion resistance.
Borofuse- The best abrasion resistance coating available, only available in Inconel
Titanium Nitride - Wear and adhesion resistance can be used in most diaphragm materials.
Titanium Aluminum Nitride - Improved wear and adhesion resistance, standard on MPS sensors (inconel diaphragm material)
Note * Consult MPS for alternative materials and coatings not listed *
MPS is committed to producing pressure sensor solutions that will provide reliable and long-lasting service for the plastics industry.
We welcome the opportunity to improve our products and encourage your feedback!