Diaphragm valves are the most reliable solution for the corrosive and abrasive flow of media. The characteristics of this valve work well to provide an efficient and cost-effective application. The earliest diaphragm valves were made by the Greeks and Romans. They used them to regulate the flow and temperature of water used in hot baths. Early Greek and Roman diaphragm valves consisted of a leather diaphragm that sealed when an operator manually pressed the diaphragm into a raised section called a weir.
With all the amazing benefits it can do, Check out how diaphragm valves work and see if they are the perfect choice for your needs.
- Diaphragm valves use a flexible diaphragm connected to a compressor by a stud which is molded into the diaphragm.
- Instead of pinching the liner closed to provide shut-off, the diaphragm is pushed into contact with the bottom of the valve body to provide shut-off.
This creates an airtight seal that opens and closes when pressurized air is applied. The media flows through small holes in the diaphragm which allows it to be actuated quickly and accurately. Diaphragms can also be used on throttling applications where flow needs to be controlled more precisely. When selecting a diaphragm valve, it is important to choose the right diaphragm material for the application. Diaphragms are available in a variety of materials including rubber, PTFE, and metal. Each type of material has its own set of benefits and drawbacks that must be considered before making a selection.
- Rubber diaphragms are the most common type used in general purpose applications. They are inexpensive and have good abrasion resistance. However, they can be damaged by certain chemicals and are not recommended for use with steam or high temperature media.
- PTFE diaphragms are chemical resistant and can be used with steam or high temperature media. However, they are more expensive than rubber diaphragms and can be damaged by abrasion.
- Metal diaphragms are the most durable type of diaphragm and can withstand high temperatures and harsh chemicals. However, they are more expensive than rubber or PTFE diaphragms and can be damaged by abrasion.
Diaphragm Valve Types and How it Works
There are two main categories of diaphragm valves: one type seals over a weir and the other (sometimes called a “full bore or straight-through” valve) seals over a seat. In general, straight-through diaphragm valves are used in on-off applications and weir-type diaphragm valves are used for control or throttling applications.
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traight-through Diaphragm Valves (Full Bore): Designed with a straight flow channel, these valves minimize pressure drops within the system. They work by the diaphragm acting as a straightforward seal. When the actuator compresses the diaphragm, the flow is completely shut off. This makes them ideal for on/off applications such as isolating equipment, opening or closing pipelines, or redirecting flow.
- Advantages: Offers full-flow capacity with minimal pressure drop, making them ideal for on/off applications, viscous fluids, and systems where smooth flow is critical.
Weir-type Diaphragm Valves: These valves feature a raised ‘weir’ within the valve body. When the diaphragm is lowered by the actuator, it rests against this weir, creating a controlled restriction. This design allows for precise flow control and throttling. Weir-type valves excel in applications where modulating the flow rate is crucial, like regulating pressure, managing flow in mixing processes, or accurately dosing chemicals.
- Advantages: Superior flow modulation, suitable for slurries and abrasive fluids due to reduced contact area with the seat.
Basic Operation
- Closed State: When the valve is closed, the actuator pushes the compressor down, compressing the diaphragm against the valve seat (either a weir or the valve body base) and creating a tight seal.
- Open State: To open the valve, the actuator retracts, lifting the compressor and allowing the diaphragm to relax and move away from the seat, creating a flow passage.
- Throttling (Weir Valves): Weir-type valves can partially compress the diaphragm against the weir, proportionally restricting the flow for control and modulation.
Material selection for diaphragm valves is crucial for successful operation. Consider the specific characteristics of the fluid that will be handled, including corrosiveness, presence of abrasives, and temperature. If the fluid is acidic, alkaline, or otherwise chemically reactive, choose a diaphragm and body material compatible with that substance. For fluids containing sand, grit, or other abrasive particles, a durable diaphragm material and a wear-resistant valve body lining are essential. Additionally, ensure that the chosen materials can withstand the operating temperatures of your system. Due to their material versatility and isolating design, diaphragm valves excel in industries where fluid handling is critical, such as chemical processing, water treatment, food and beverage, and pharmaceuticals.
If you need diaphragm valves in the UK that stand to be reliable and cost-effective solutions for your next project be sure to check us out. KDV Flow Limited UK is known for its fast turnaround time and lead times when it comes to order fulfillment. It’s made possible by having large stocks of lined valves (different types and Ranges) at our warehouse in Wakefield.
