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Diaphragm Valves
Derwent Industries high quality and reliable thermoplastic diaphragm valves will handle dirty and abrasive fluids. Derwent Industries AVFI diaphragm valves includes a manual rang and a pneumatic or electric actuated range. AVFI diaphragm valves are available in sizes from DN 10 (10 mm) to DN 100 (100 mm) and come with spigot weld ends, EPDM diaphragms are standard. Derwent Industries AVFI thermostatic diaphragm valves are available in different plastic body material such as U-PVC, C-PVC, PVDF, PP and seat materials such as EPDM, Viton, PTFE and FPM, designed to suit many chemical application. Refer to appropriate data sheet for full details on Derwent Industries diaphragm valves.
FAQ
How does a diaphragm valve work?
A diaphragm valve controls or shuts off flow using a flexible elastomeric diaphragm that is pressed down against a weir or valve seat by a compressor mechanism.
Opening: Turning the handwheel or activating the actuator raises the compressor, lifting the flexible diaphragm off the seat to allow full, unobstructed flow with minimal pressure loss.
Closing: Rotating the non-rising handwheel lowers the compressor, pressing the diaphragm firmly against the valve body to create a bubble-tight, leak-free seal.
Sealing Advantage: The diaphragm completely isolates the internal fluid media from the valve drive mechanisms (spindle, sleeve, bonnet), preventing contamination, corrosion, and fluid buildup inside the working parts.
What are the main types of diaphragm valves offered by Derwent Industries?
Derwent Industries supplies a modular range of high-quality thermoplastic FIP diaphragm valves across various actuation types and body/seat material combinations:
Manual Diaphragm Valves (VM Type): Operated via a non-rising handwheel fitted with a metal spindle, metal sleeve, and POM compression bearing for up to 40% reduced operating torque.
Actuated Diaphragm Valves: Equipped with electric or pneumatic actuators for automated process control and remote system operation.
Thermoplastic Body Options: Constructed from durable, chemical-resistant polymers including U-PVC, C-PVC, PVDF, and PP.
Diaphragm & Seat Materials: Fitted with EPDM as standard, with options for Viton, PTFE, and FPM to suit aggressive chemical media.
What are the primary applications and common uses for diaphragm valves?
Thermoplastic diaphragm valves are designed specifically for challenging fluid handling environments where traditional metal valves might corrode or clog:
Chemical Processing & Handling: Transporting aggressive acids, alkalis, and corrosive chemicals without body or stem degradation.
- Dirty, Slurry & Abrasive Fluids: Handling fluids containing suspended solids, slurries, or crystallizing media, as the smooth valve design prevents deposit accumulation and clogging.
- Water & Wastewater Treatment: Potable water regulation, chemical dosing, and wastewater management where low mechanical stress and reduced water hammer are critical.
- High-Purity & Fine Process Lines: Applications requiring zero fluid contamination, easy internal cleaning, and minimal dead space.
What are the Key Performance Advantages of Diaphragm valves?
- Reduced Water Hammer & Torque: Handwheel operation and smooth diaphragm sealing enable gradual flow regulation, minimizing line shock and cutting closing torque by up to 40%.
- High Flow Efficiency (High Kv Value): Compact and sturdy construction optimized for minimal pressure loss and streamlined fluid dynamics.
- Modular Engineering: Uses 5 diaphragm and bonnet sizes across 9 different body dimensions, simplifying maintenance and spare parts inventory.
- Corrosion & Contamination Protection: Complete isolation of mechanical drive components from the process fluid prevents fluid contamination and crystallizing media damage.
Diaphragm Valves Main Types & Feature Comparison
| Gate Valve Type | Key Features | Primary Applications |
|---|---|---|
| Resilient Seated (RSGV) | Features an elastomer-encapsulated wedge that seals tightly against the inner valve body. Offers zero leakage and smooth, obstruction-free flow passage. | Potable water distribution, sewerage mains, and general fluid isolation complying with AS 2638.2. |
| Metal Seated (MSGV) | Employs precision-machined metal ring seats for high resistance to wear, elevated temperatures, and abrasive media. | Raw water intake, industrial processing, and high-wear piping systems. |
| UL / FM Approved Fire Valves | Certified to international fire protection standards, providing fail-safe shut-off capability under emergency conditions. | Dedicated fire ring mains, hydrant lines, and commercial sprinkler systems. |
| Rising Spindle / Stem (RSGV RS) | The stem rises vertically as the valve opens, providing a clear visual indication of whether the valve is open or closed. | Above-ground plant piping, pump stations, and treatment facilities where visual position check is essential. |