Saunders® EX Endurance Diaphragm



Saunders® EX Endurance Diaphragm features two-piece leaf-type construction. The diaphragm consists of a wetted modified PTFE face with a non-wetted fabric reinforced Silicone backing cushion.

The Silicone backing offers exceptional resistance to high temperatures compared to EPDM. EPDM rubbers suffer damage with prolonged exposure to temperature such as encountered during heat sterilization. This damage results in loss of resiliency and resistance to compression set and reduces the ability of the EPDM backing to properly energize the wetted PTFE diaphragm face.

The EX Silicone backing can handle these same elevated temperatures with no deterioration of physical properties.

The Saunders® Endurance Diaphragm is also ideal for applications that require service at unusually high temperatures. The EX Diaphragm has been tested on continuous steam at 175°C (347°F).






Features and Benefits 


Key features of the Saunders® EX Endurance Diaphragm include:


  • Outstanding high temperature performance and resistance to long term exposure at elevated temperatures
  • Ideal for steam distribution and supply, sterile barrier, and block-and-bleed applications
  • Improved seal-to-atmosphere performance and reduced requirements for re-torqueing of fasteners after thermo cycling



Back to Top


Pressure and Temperature



  • Maximum constant 175°C (347°F)
  • Maximum intermittent 175°C (347°F)
  • Minimum temperature - 20°C (-4°F)



Back to Top




  • FDA-compliant to 21CFR part 177
  • USP Class VI <87>, <88> (third party tested)
  • ASME BPE part SG
  • Certified ADCF (Animal Derived Component Free)
  • Fully lot traceable to EN 10204 3.1

Use only genuine Saunders® spare parts to ensure optimum performance, reliability, and regulatory conformance.



Back to Top


Frequently Asked Questions (FAQ)


What is the EX Endurance Diaphragm?

The EX Endurance Diaphragm is a two-piece leaf-type diaphragm with a silicone backing and a modified PTFE facing.

Why is the EX called the “Endurance Diaphragm”?

The EX Endurance Diaphragm has been developed for high temperature applications and, especially, applications which expose the diaphragm to high temperatures for long periods of time. The EX will endure these high temperatures without damage.

Why use a silicone backing?

Silicone has excellent thermal properties and it can withstand very high temperatures without deterioration. Also, it can handle high temperatures for very long periods of time without damage. Silicone holds up well at low temperatures. Plus, Silicone has best-in-class resistance to compression set – much better than EPDM or other rubbers.

Why is resistance to compression set important?

Compression set is the loss of recovery that elastomers suffer from being compressed (“squeezed”). This property is critical for backings that must provide resiliency that PTFE facings lack. After compression, elastomers spring back to their original form, less any compression set. Under heat and time this ability diminishes. Silicone not only has an overall better recovery – or resistance to compression set – it also has best-in-class thermal and antiaging properties.

Are there other benefits to improved resistance to compression set?

Yes, the requirement to retighten fasteners after thermo cycling is diminished. While this practice is still recommended 24 hours after first heat cycle, further demands are reduced.

Why not use silicone as a body diaphragm instead of a backing cushion?

Silicone has great thermal and compression set properties but is not immune to attack by hot water and especially steam. Steam attacks the Si-O-Si backbone and results in de-polymerization of the material.

Does the steam damage the silicone?

No, silicone backing is protected from the line media by the PTFE face.

What is the temperature range for the EX diaphragm?

The EX Diaphragm has been tested to 175⁰C (347°F). The EX also offers excellent low temperature performance and is rated to -20⁰C (-4°F). Consult factory for applications above and below these temperatures.

What are typical applications for the EX Diaphragm?

The EX is ideal for steam supply and distribution, steam blocks/sterile barrier assemblies, and any other applications that subject the diaphragm to high temperature for extended periods of time. Also, any applications that require a wide range of thermo-cycling – for example, valves that see cold product after heat sanitization.

Does the EX Diaphragm comply with industry standards?

Yes, the EX is FDA-compliant, third party tested to USP Class VI, <87>, <88>, it is certified ADCF (Animal Derived Component Free), meets requirements of ASME BPE part SG, and is fully lot traceable.



Back to Top


Marking and Identification


Marking system includes, date of production, cure date, diaphragm grade, size, and Saunders® ID to provide full traceability.

The EX Endurance Diaphragm features Saunders® bayonet type compressor attachment for optimum performance and ease of assembly DN15-100 (½"-4") and screw fix DN8 (¼").



Back to Top


Design Features


Modified PTFE Wetted Face

  • Optimum ratio of crystalline and amorphous microstructure
  • Reduced creep and fl ow at elevated temperatures means less deformation
  • Ideal for high steam applications

Silicone Backing Cushion

  • Dicumyl peroxide cured
  • Outstanding thermal properties
  • Best-in-class resistance to compression set
  • Fabric reinforced to optimize fl ex performance



Back to Top





The ideal solution for applications that have extended exposure to high temperatures such as during steam sanitization. This includes:

  • Steam block
  • Sterile barrier
  • Steam distribution and supply
  • Process lines subjected to long duration steam cleaning



Back to Top




  • DN8-200 (¼"- 8")



Back to Top


Literature Documents


Specifications and Literature
Saunders® HC4 EX Endurance Diaphragm - Datasheet (EN LT)
Saunders® HC4 EX Endurance Diaphragm - FAQ (EN LT)
Saunders® HC4 EX-Langzeitmembran - Datenblatt (DE A4)
Saunders® HC4 EX- Langzeitmembran - Fragen & Antworten (FAQs DE A4)
saunders hc4 special diaphragm ex endurance

Copyright © 2017 Crane Co. All Rights Reserved.