Diaphragm Material Overview
Diaphragm materials vary not only in chemical compatibility but also in mechanical performance and cost. Before diving into the comparison table, here’s a quick summary of the key characteristics that differentiate each material:
- EPDM: Excellent heat and ozone resistance. Performs well in high-cycle and suction lift applications. Not suitable for oils or hydrocarbons.
- Neoprene: Offers good abrasion resistance. Suitable for moderate chemical exposure and flexible across various operating conditions.
- Nitrile (Buna-N): Strong resistance to oils and greases. Highly durable in abrasive and petroleum-based applications.
- PTFE: Outstanding chemical and temperature resistance. Best for aggressive chemicals and sanitary use. Often paired with a backing layer for flexibility.
- Santoprene: Excellent flex life and mechanical durability. FDA-approved options available for hygienic environments. Moderate chemical resistance.
- Viton: Exceptional chemical and temperature stability. Performs well in harsh, high-heat environments. More rigid and expensive than other elastomers.
Selecting the right diaphragm involves balancing chemical compatibility with performance factors like temperature limits, flex life, abrasion resistance, and cost. Use the table below for a detailed material comparison, and consult our Chemical Compatibility Page to ensure fluid compatibility.
Comparative Table
| Material |
Suitable for |
Temp Range Min/Max (C) |
Cost |
Flex Life |
Abrasion Resistance |
Chemical Resistance |
Temperature Limitations |
| EPDM |
Acids, alkalines, water-based applications |
-40 to 138 |
Medium |
Good |
Good |
Good |
Great |
| Neoprene |
Refrigerants, mild acids and alkalines, water and light oil mixtures |
-23 to 93 |
Low |
Great |
Good |
Not recommended |
Good |
| Nitrile (Buna-N) |
Oils, greases, hydrocarbons, abrasive fluids like ceramic slurries |
-23 to 88 |
Low |
Great |
Good |
Limitations |
Good |
| PTFE (Synthesis) |
High-purity and aggressive chemicals, solvents, acids, and clean fluids in sanitary or pharmaceutical applications |
-10 to 80 |
High |
Good |
Limitations |
Great |
Limitations |
| PTFE (Two-Piece) |
Aggressive chemicals, solvents, acids, light slurries, and industrial fluids requiring chemical resistance |
-37 to 104 |
High |
Limitations |
Not recommended |
Great |
Good |
| Santoprene |
Water, mild chemicals and cleaners, food and beverage service, light slurries |
-40 to 135 |
Low |
Great |
Great |
Great |
Great |
| Viton (FKM) |
Strong acids, oils, fuels, and high-temperature applications |
-40 to 177 |
High |
Not recommended |
Limitations |
Great |
Great |
Application-Based Recommendations
- Food & Beverage: Use Santoprene® or PTFE (FDA-compliant grades). Both materials are suitable for hygienic environments, with PTFE offering superior chemical resistance and Santoprene providing excellent flexibility and durability.
- Oil & Gas: Opt for Nitrile (Buna-N) or PTFE. Nitrile is well-suited for petroleum-based fluids and offers good abrasion resistance, while PTFE is ideal for aggressive chemicals and elevated temperatures.
- Chemical Processing: Choose PTFE or EPDM. PTFE delivers broad chemical compatibility and high thermal resistance, whereas EPDM is reliable for handling a wide range of mildly aggressive chemicals, particularly in alkaline environments.
- Water & Wastewater: Select EPDM or Santoprene®. EPDM performs well with water-based applications and has good weathering resistance; Santoprene, being a thermoplastic elastomer, offers superior flex fatigue resistance for high-cycling conditions.
Performance Tips
- In high-cycling applications, Santoprene® often outperforms EPDM due to its enhanced resistance to flex fatigue and mechanical stress.
- PTFE, although chemically inert and suitable for high-temperature environments, is a stiff material with limited elasticity. It performs best when paired with a backing diaphragm, often Santoprene, to improve flexibility and extend service life.
- For abrasive slurries, particularly in the ceramics industry, Nitrile seats combined with stainless steel balls ensure fast closure and improved wear resistance.
- EPDM and Santoprene® are both suitable for suction lift applications, but Santoprene’s lower density may make it less ideal for use with very viscous fluids.
Diaphragm Maintenance & Replacement Tips
Recognising Diaphragm Wear
- Regular inspection is key to avoiding unexpected pump failures. Common signs that a diaphragm may need replacing include:
- Blistering or bubbling on the surface, often caused by chemical attack or gas permeation
- Cracking, particularly around flex points, indicating fatigue or ozone damage
- Deformation or stretching, which may lead to reduced performance and poor sealing
Preventative Diaphragm Maintenance Advice
- Use pulse dampeners: These reduce pressure spikes, helping to extend diaphragm flex life and reduce vibration-related wear.
- Schedule routine inspections: Check for wear signs every 3–6 months, especially in high-cycling or abrasive applications.
- Use backup diaphragms where recommended: Pairing stiffer materials like PTFE with a softer support (e.g. Santoprene®) can significantly improve durability.
- Match materials to fluids: Ensure chemical compatibility charts are consulted when selecting diaphragms to avoid premature failure.
Additional Reading
Chemical Compatibility Calculator
What Is a Diaphragm Pump and How Does It Work?
Learn more about FDA Certification
