Penstocks
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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.
Frame
The 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.
Door
The 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 assembly
All 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 Frame
Guides 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 Nut
Each 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 Spindle
The 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 Guides
Stem 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 operation
For 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.
