Earlier this summer, KSB announced that it was launching a special version of a butterfly valve specifically geared to the needs of fire-fighting service. This as a complement to its existing range of butterfly valves.
The new BOAX-B FM valves, painted in red, are fitted with a specially designed gearbox. Suitable for an operating pressure of up to 16 bar, the valves are available from DN 40 to DN300.
The abbreviation FM stands for Factory Mutual, an international set of requirements for fire protection applications in industry and building services (see box).
As KSB explain, fire-fighting systems pose a challenge for valves as the piping can be subjected to full pressure for a year or two without the valve being actuated. The one-sided load presses the liner of butterfly valves in the downstream direction. This may result in leakage if the elastomer quality is inadequate.
KSB’s design and the liner quality used ensure that the liner does not move, also under pressure, thus providing permanent and lasting tightness.
The spherically machined valve disc and the liner, which is moulded accordingly, make for a perfectly tight shut-off at the stem passages.
This design principle prevents the stem from coming into contact with the fluid. The elastomer liners also provide sealing at the flanged line connections, eliminating the need for additional gaskets.
Yellow flag for visibility
To enable power transmission between the blowout-proof stem and the valve disc, KSB’s engineers opted for a positive connection.
The valve is actuated by a manual gearbox which is also painted in red. A yellow flag of 100 x 100 mm, which is also visible from a distance, indicates if the butterfly valve is open or closed.
A chain fastened to the gearbox prevents unauthorised actuation of the handwheel, and a locating device ensures that the manual gearbox is mounted in the correct position.
As an option, the gearbox can be fitted with two internal limit switches.
The new BOAX-B FM valves satisfy the safety requirements of Annex 1 of the European Pressure Equipment Directive 97/23/EC. The flange connections comply with the EN, ISO and ASME standards.