Seguro resilient seated Gate Valve
The Seguro valve represents a well proven concept in gate valve design; it is unique in that the sealing of the gate valve is effected by a soft rubber seal, firmly secured by a special wedge. The wedge is guided by grooves, cast into the valve body. Because the Seguro has no seat rings in the body, a smooth full bore is achieved. This, plus the self flushing design of the valve body, eliminates possible build-up of sediments or other foreign matter in the valve body. The result is a minimum of maintenance and 100% tight closure.
The packing gland has been replaced with a double o-ring seal embedded in nylon. Valves with rising stem use U-packings in a brass bushing. This design assures positive seal at the stem and minimizes maintenance.
The above features, combined with simple but sound engineering practices, assure an ideal shut-off valve for almost all installations and media. Thus resulting in 100% closure, high reliability in service and long life with a minimum of maintenance, makes the Seguro a logical choice for economical and trouble free service. An extensive manufacturing program has made the Seguro valve an ideal choice for your particular application.
Manufacturing standards: American, British, German
Pressure classes: 125, 250 (cast iron and ductile iron)
Body and bonnet: Cast iron and ductile iron
Trim: Seals: Nitrile butadien rubber (NBR) or EPDM
Stem: Stainless steel
Nut: Brass or cast iron
Bonnet bolting Hot galvanised or stainless steel
Operating methods: Hand wheel, bevel or spur gear, electric, pneumatic or hydraulic cylinder
Seguro gate valves are cast, machined, assembled and tested following the best workshop principle and rigid controls. All moving parts are thoroughly lubricated with molybdenium sulphide grease, each valve is coated inside and outside with a special corrosion resisting plastic (polyacrylate/isocyanate) or to the customers specifications. Finally each and every valve is tested to conform to the standards outlined on the specification sheets.
Rising stem valves with outside stem and yoke (OS &Y) On these valves the stem passage are designed as follows:
A brass bushing, which serves as a guide for the stem, is pressed into lower end of the yoke. This bushing is machined to contain the stem packing.
The stem seal is a self-tightening U-cup seal, and is secured by a stainless steel locking ring. The yoke is bolted to the bonnet on all sizes.
The stem thread used is trapezoid.
If the valve is with hand wheel, this in mounted on a brass nut at the top of the yoke. This nut is kept in place by two ring-nuts, one over the hand wheel and one inside the yoke opening.
In case of an actuator or a reduction gear is used; the thread is cut in the insert bushing of the actuator. The yoke will then be equipped with a standard flange (ISO 5210) at the top.
The standard material is brass, but the nut is also available in bronze or cast iron for improved corrosion resistance. The stem nut is loosely fitted into the pressure piece to prevent radial load of the stem. In the valves with OS&Y, a screw in the stem nut prevents the stem from rotating.
The wedge (or gate) consists of half shells (bolted together with stainless steel bolts), a pressure piece and the rubber seal. When assembled, the two halves and the pressure piece form a groove in witch the rubber seal is retained and protected. Projections are cast on the bottom of the wedge, these acts as a stop and prevent overloading of the rubber seal. The valve cannot be over seated. A drain hole is provided in the bottom of the seal to prevent stagnation of water.
The wedge is shown as it is about to be seated. Note that the seal touches the bottom of the port area as well as the vertical walls of the valve body, there are no projections. The valve is now fully seated and closed tight. Note that the seal is firmly pressed against the bottom of the valve passage, and the pressure piece has forced the seal radial outward, effectively sealing the vertical walls of the valve.