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It’s a diaphragm valve but not as we know it

Bürkert’s Robolux diaphragm valve addresses wastage and dead volume with an innovative 3-way design that eliminates dead legs and any need for heavy valve block assemblies. Process Industry Forum spoke to Ian Webster, Field Segment Manager for Hygienic Processing at Bürkert, to find out how Robolux has changed the diaphragm valve as we know it.

Robolux provides a three-way diaphragm valve

A diaphragm valve is the only truly hygienic valve. There are other valves that are listed as being hygienic, which are used in breweries and dairies, but in the ultra-pure biotechnology and pharmaceutical industries they exclusively use diaphragm operated control valves.

This is because diaphragm valves are easy to drain; they’re two-way, so have two connections; there are no crevices inside; they provide a smooth flow through them; and you can polish the insides, so they’re very sterile.

The problem with a standard pneumatic diaphragm valve is that it’s just a single seat valve with an inlet, an outlet and an actuator on it. The diaphragm opens and closes to let flow through the valve. With a lot of valves used in industry, you can have a two-way valve and a three-way valve, so you have a third port inside the valve and the actuator closes one port and opens another.

You can’t do that with a traditional diaphragm valve because it’s only a two-way valve. Bürkert introduced the Robolux valve, which employs two pistons in one actuator to create a three-way type diaphragm valve.

Compact and lightweight 4-valve seat blocks

A conventional diaphragm control valve has a weir across the middle that seals the flow from one side to the other. The Robolux valve has two weirs and a gap in between the two, which is like a third port. The actuator allows you to open one weir, so the flow comes in and then goes out through the middle outlet.

You can close that weir and then open the other weir and get flow from the other way and that goes out of the outlets. Conversely, if you have flow coming up from the middle, you can divert it one way or the other. It then becomes a divert or mixing valve. There is no other pneumatic diaphragm control valve that can do that.

The beauty of the Robolux is that we’ve developed a way in which you can put an actuator on either side of the valve. If you take this valve with two weirs on one side and then machine the same on the other side you then have four valves in one small block with two actuators on it. A 4-valve seat block using a conventional pneumatic diaphragm valve is quite a big lump of stainless steel. We can get the same functionality with a much smaller lump of stainless steel.

Bürkert

Robolux delivers 50% less dead volume

If you have a diaphragm control valve in a certain orientation and you open it, it will drain itself. When you start to combine these in a block, so that you have multiple seats, you can never get it to drain – there’s always an internal dead volume.

That can be a problem, certainly for some parts of the Pharmaceutical industry, where the product they’re manufacturing is very high value. That little volume of the product could be worth several thousand pounds. What we’ve done with the Robolux valve is make that block a lot smaller. Also, because we’ve got this double weir valve, the internal dead volume inside the valve is reduced by 50% or more.

The Robolux valve reduces that internal waste and so reduces the cost of lost product. It also makes it possible to make the valve block more complicated and get more valves into it because each valve in itself is a 3-way valve rather than just a 2-way valve. With Robolux, you can get more diaphragm valves in the same space of valve seats than a conventional one.

For more information visit Bürkert.

Company Profile

Bürkert Fluid Control Systems

Bürkert Fluid Control Systems is a world-leading manufacturer of control and measuring systems for fluids and gases.

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