Penstocks

Penstocks are commonly used isolation devices with practically zero maintenance. It has either a cast iron or fabricated body with soft material exchangeable sealing arrangement. Penstocks are both manual and power operated.The gates are of self containing type design.The main components are:Frame wall bolted for sizes up to 1300 mm, ~ concrete grouted for larger sizes or flanged for pipe connections. Door roller guided for easy operation.Guides with adjustable wedges, assuring a maximum of tightness.Seals Non-ferrous metal /abrasion resistant rubber.Stem rising or non-rising design.Drive of manual or electrical operation. MACMET gates are of high corrosion resistance which makes them suitable for water collecting systems, waste water treatment plants and various other applications. FrameThe frame is manufactured from cast-iron/stainless steel/galvanized steel. The flat backed design of the penstock gate makes it suitable for installation against a wall, by bolting and in recesses. DoorThe door is manufactured from cast-iron/stainless steel/galvanized steel. It is of robust construction suitably strengthened with ribs or trapezoidal ribbing dependent upon the specific use. The sealing strips are secured to the frame in such a way that liquid seepage between the sealing faces is eliminated. The door is designed for the specified maximum head.Roller assemblyAll gates are designed with a wedging system. To reduce water forces for gate sizes above 600 mm, the door is guided by rollers. During the opening of the gate, a slope in the guide rail moves away the door from the sealing surface. The adjustable stepped wedging system ensures that when in closed position, the door is pressed against the sealing surface providing a watertight seal.Penstocks are designed to be as tight as possible. Installation factors beyond the control of the manufacturer can seriously affect leakage. Leakage depends on door size and water pressure on the front or back (unseating head) of the door.Guide FrameGuides are made of the same material as the frame and the door. The guides are bolted to the machined surfaces of the frame. They are designed for the specified maximum head. The length of the guides makes it possible to guide the rollers for a full opening of the door. The guides are capable of taking the entire thrust produced by the wedging action, even if the door is forced by unseating head pressure.Thrust NutEach door is provided with a thrust-nut pocket. This pocket is bolted to the door and manufactured from the same material as the door. The thrust-nut pocket is designed to prevent any turning of the nut during operation and is capable of withstanding the operating forces. The thrust nut is made of brass or bronze.Stem and SpindleThe gate is operated via a solid stem with a threaded spindle. Operating stems are of a size to safely withstand, without buckling or permanent distortion, stresses induced by normal operating forces. Stems are fabricated from solid stainless steel bars. Where stems are provided in more than one piece, the different sections are joined by solid couplings of the same material.Stem GuidesStem guides are provided where necessary to hold the stem and spindle in alignment. Stem guides are of cast iron, with bronze bushings and mounted on cast iron brackets. The guides are adjustable with regards to the brackets to provide proper concentric alignment with the stem. The stem guide brackets are rigidly fastened by grouting into wall pockets or by bolts after alignment.Drives for operationFor smaller sizes tee-key operating drives are possible. Floor stands of appropriate design for handwheel or with electric / pneumatic gear box are used for gate sizes above 600 mm.