A double acting pneumatic wafer butterfly valve is a butterfly valve that is designed to clamp between two flanges without the need for the bolts to go through threaded holes on the body of the butterfly valve. It has a direct mounted anodised aluminium rack and pinion actuator fixed to the valve which conducts its 90 degree turn (open/close). The valve body sits like a 'wafer' between the flanges and therefore fit multiple flange standards unlike lugged which will be designed to fit only one standard. In this case we are talking about ductile iron (similar to cast iron but better advantages in terms of strength, elongation & life) center line wafer butterfly valves. The center line refers to the location of the disc and shaft in relation to the body (there are other kinds of butterfly valves such as double & triple offset) where it is precisely in the middle. These valves can have different seat materials but the most common would be EPDM but others such as FKM, NBR or PTFE are also used. The actuator has a namur interface and position indicator.

A butterfly valve works by the shaft rotating 90 degrees which will take the position of the disc in the flow from open to close (or vice versa). When it is closed a seal will be formed between the disc and the seat effectively stopping the flow of the media. When it is opened again the disc comes away from the seat and when it is fully open sits side (smallest surface area facing) on to the direction of the upstream flow. This 90 degree turn is conducted by a double acting rack & pinion actuator which is connected to a shaft which in turn is mated to the disc by a spline. When the actuator is operated by a 5/2 valve (all double acting actuators need a 5/2 valve to operate, the most common we see is a 5/2 direct interfacing namur solenoid valve) the shaft will be rotated effectively turning the disc, switching it to its other state (either open or close). Extras such as limit switch boxes and positioners can also be mounted directly to the actuator.

Like any valve this depends upon the usage case of your butterfly valve, its environment, media and how many times it is cycled. For instance if it is on a clean wet media, in a clean environment and not cycled regularly the life will be decades. If it is on a corrosive media and in a dry application with a high cycle rate the life will be much shorter. We conduct regular lab testing and 6,000 cycles is a reasonable life cycle depending upon the application. One advantage of this design is that the seat is replaceable and available as a repair kit. The actuators life will depend upon how clean and dry the supply air is (the air that makes the actuator operate) however we regularly test these to over 800,000 cycles. Install a basic air filter if you are not sure about the quality of your air, we have pneumatic actuators that have been in operation for decades. The most common failure we see is due to dirty wet air being sent to the actuator.

These wafer butterfly valves are designed to clamp between two flanges. The bolts will pass through from one flange to the other to give the clamping force on the valve and keep it in position. The seat of the valve also forms the gasket on the flanges so there is no need for a secondary gasket. The bolts should be tightened in a diagonal shape to avoid over tightening in one area. For a full list of instructions please visit our butterfly valve installation & maintenance guide. The double acting actuator can accommodate a namur solenoid valve which is a very popular configuration (the 5/2 control valve bolts directly onto the actuator with an o-ring face seal on the back of the valve) or just a stand alone 5/2 valve. If you are using a stand alone 5/2 valve the air lines will need to be run from here into the ports on the actuator (remember the longer the run the slower the operation unless you use quick exhaust valves near the actuator).

These are very common in the water industry especially because most of our models hold a Watermark and Standards mark approval. They are also used for general purpose applications as long as the media, temperature and pressure are compatible. One main advantage of butterfly valves is they are relatively cheap compared to their size if you are comparing to another valve type (eg. ball valve). Being double acting they are not used in fail safe applications where you need the valve to fail to a particular positon (open or close) if you lose air, this would best be served by a spring return unit.

This depends upon where you are based and the freight method chosen. If the express freight option is selected it is usually next day delivery to metropolitan areas in Australia for under 5kg. If free freight has been selected it will go by road freight which can be anywhere from 1 to 10 days depending upon your location. It usually averages 3 days.

All of our products come standard with a 12 month warranty. The good news is we have very strict quality controls and all valves leave our warehouse tested (full material and testing certificates to API 598 are available) and inspected so there are rarely any issues. Also once your valve is in and operating it will most likely continue to do so for a very long time.