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Diaphragm Valves

A diaphragm valve, designed for isolation and throttling tasks, features an elastomeric diaphragm controlled by a plug for flow regulation. When the diaphragm contacts the valve body’s seat, it completely isolates the flow. 

Introduction

Diaphragm Valves by John Valves

A diaphragm valves are used for both isolation and throttling. It is manufactured with a diaphragm that is pressed by a plug above the diaphragm into the flow to throttle or isolate the flow of the media. Complete isolation occurs when the diaphragm comes in contact with the seat inside the valve body.

Available in “straight-through” or “weir” styles. In a weir-style diaphragm valve, the internal body surface is shaped so the media flows over a ridge or saddle. This type is better suited for throttling applications due to its quick opening characteristic. As the straight-through valve name suggests, it has a straight-through flow path. However, it is not a full port, as the diaphragm protrudes into the flow at the top of the valve. 

These give better flow characteristics than “weir” style valves, making them better suited for slurries, sludges, etc. They are not as accurate when throttling or suitable for higher temperature fluids due to the design of the diaphragm, which has to be more flexible to seal on the bottom of the valve body.

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Diaphragm Valve Products

Gate Valve 3004

JOHN FIG 3004

Flanged Straight Through
Item Details
Body Material
Cast Iron
Body Coating
-
Trim
Butyl
Pressure Range
PN16
Size Range
DN50-DN300
Flange Connection
AS2129 Table D & E / ANSI
End Connection
-
Options
Epoxy Coating / EPDM / Natural Rubber
Gate Valve 3002

JOHN FIG 3002

Threaded Weir Type Diaphragm
Item Details
Body Material
Cast Iron
Body Coating
-
Trim
Butyl
Pressure Range
PN16
Size Range
DN50-DN300
Flange Connection
AS2129 Table D & E / ANSI
End Connection
BSPF
Options
Epoxy Coating / EPDM / Natural Rubber
804 Ball Valve

JOHN FIG 3001

Threaded Weir Type Diaphragm
Item Details
Body Material
Cast Iron
Body Coating
-
Trim
Butyl
Pressure Range
PN16
Size Range
DN15-DN50
Flange Connection
AS2129 Table D,E&F / ANSI
End Connection
BSPF
Options
Epoxy Coating / EPDM / Natural Rubber

Diaphragm Valve Technical Sheets

Our commitment to industry to supply quality diaphragm valves, we have made these technical sheets available. If you need further information please make a technical enquiry.

power industry

Excellence in the Design & Engineering

Our diaphragm valves are expertly engineered for precise flow control and isolation, ensuring efficient and reliable operation in various systems. Their durable construction is designed to handle demanding conditions, maintaining top-notch performance and flow regulation.

The uniqueness of our diaphragm valves lies in their adaptability and effectiveness. They are ideal for various applications, from intricate industrial processes to essential domestic systems. Our collection includes “straight-through” and “weir” styles, each meticulously designed for specific scenarios, whether handling slurries or precise throttling.

At the heart of these valves is their contribution to system accuracy and safety, meeting rigorous industry standards. This quality stems from our unwavering commitment to research and development, guided by a customer-focused approach that constantly aims to improve our products.

Advantages of Diaphragm Valves

  • Precise Flow Control
    They allow for accurate throttling and regulation of fluid flow, making them ideal for applications requiring precise control.
  • Leak-Proof Design
    The tight seal formed by the diaphragm against the valve body ensures leak-proof operation, which is critical in many industrial processes.
  • Versatility
    Suitable for various media, including abrasive and corrosive fluids, gases, and slurries. Their adaptability extends to multiple industries.
  • Low Maintenance
    The simple design and limited number of moving parts reduce the likelihood of mechanical failure and lower maintenance requirements.
  • Hygienic Operation
    With no cavities or dead zones where particles can accumulate, diaphragm valves are ideal for sanitary applications, such as pharmaceutical and food industries.
  • Bi-Directional Flow Capability
    They can handle fluid flow in both directions, adding to their versatility in system design.
  • Safe for High-Purity Applications
    They are suitable for high-purity applications due to minimal contamination risk.
  • Minimal Wear and Tear
    The operating mechanism of diaphragm valves, typically less strenuous than in other valve types, leads to reduced wear and a longer service life.
  • Ease of Operation
    Their straightforward design, often with simple actuation mechanisms, makes them easy to operate, even in complex systems.
Power industry worker maintaining valves

Industry Uses

The diverse use of diaphragm valves across these industries underscores their importance in ensuring safe, efficient, and reliable flow control in a multitude of applications. Their ability to adapt to different environmental conditions and fluid properties makes them indispensable in modern industrial and commercial operations.

Industries that commonly utilise check valves include:

Power Generation

For controlling gases and fluids in power plants. In cooling systems and waste management processes.

Chemical Processing​

Handling corrosive and abrasive chemicals. Used in processes involving acids, alkalis, and solvents. Safe for transferring hazardous materials due to leak-proof design.

Water and Wastewater Treatment​

In filtration, desalination, and reverse osmosis systems. Managing sludges and slurries in sewage treatment. Controlling the flow in water purification processes.

Food and Beverage Manufacturing​

Essential for maintaining hygienic conditions and preventing contamination. For dosing and controlling ingredients and additives.

Pharmaceuticals

For sterile and clean processes. In systems requiring precise control of flow and minimal contamination.

Biotechnology

In fermentation and cultivation processes. For controlling sterile gases and liquids.

Mining & Minerals

Managing abrasive and corrosive slurry flows. In processes for extracting and processing ores and minerals.

HVAC Systems​

For controlling air and liquid flow in heating, ventilation, and air conditioning systems.

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Frequently Asked Valve Questions

If would like to know more, please get in touch and we’ll be happy to answer your questions.

A diaphragm valve is a type of valve that uses a flexible diaphragm to control the flow of fluid. The diaphragm, which is typically made of an elastomeric material, is pressed against a seat in the valve body to stop the flow or lifted away to allow the flow.

Diaphragm valves operate by the movement of a flexible diaphragm up and down. When the diaphragm is lowered onto the valve seat, the flow is blocked. When the diaphragm is lifted, fluid can flow through the valve. This mechanism allows for precise control of fluid flow.

Diaphragm valves offer several advantages, including a leak-proof seal, minimal contamination risk, suitability for handling abrasive or corrosive fluids, and ease of maintenance. They also provide precise flow control, making them ideal for applications in pharmaceutical, food and beverage, chemical processing, and water treatment industries.

Diaphragm valves are generally not recommended for high-pressure applications. They are best suited for moderate pressure conditions since high pressure can cause the diaphragm to deform or fail.

Yes, diaphragm valves are well-suited for handling slurries and abrasive media. Their design minimises the number of crevices where particles can accumulate, reducing the risk of valve damage and blockage.

The choice of diaphragm material depends on the type of fluid being handled. For corrosive chemicals, PTFE or rubber-lined diaphragms are preferred. For food and pharmaceutical applications, food-grade, non-toxic materials are used.

Yes, diaphragm valves are relatively easy to maintain. Their simple design and lack of internal moving parts (other than the diaphragm itself) make them easy to clean and repair.