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Mechanical or hydraulic hoists may be used to move the gates.
7. Ring-Follower Gates.
Ring-follower gates are used as guard gates for penstocks or outlet conduits and
are not suitable for water regulation. A ring-follower gate is a slide gate with a leaf, body, bonnet, and a
hoist, usually a hydraulic cylinder, to move the leaf The ring-follower gate leaf consists of two parts: the
bulkhead part which blocks the fluid flow in the closed position and the "ring" portion which has a circular
opening matching the diameter of the penstock or conduit to provide a unobstructed water passage in the
open position. A ring-follower gate is shown in
hoist, usually a hydraulic cylinder, to move the leaf The ring-follower gate leaf consists of two parts: the
bulkhead part which blocks the fluid flow in the closed position and the "ring" portion which has a circular
opening matching the diameter of the penstock or conduit to provide a unobstructed water passage in the
open position. A ring-follower gate is shown in
8. Ring-Seal Gates.
Ring-seal gates are a type of ring-follower gate with a movable seal and a wheel- or
roller-mounted gate leaf. The gate seal is hydraulically actuated by water pressure, either from the conduit
or an external source, and may be located in the housing or the leaf. The hoist may be a mechanical or
hydraulic cylinder. Ring-seal gates are shown in
or an external source, and may be located in the housing or the leaf. The hoist may be a mechanical or
hydraulic cylinder. Ring-seal gates are shown in
9. Bulkhead Gates and Stop Logs.
Bulkhead gates and stop logs are installed under balanced, no flow
conditions, and are used to allow the unwatering of a waterway such as a outlet pipe, penstock, or turbine
draft tube. In the case of outlet pipes and penstocks, they are placed as far upstream as possible to allow
the complete unwatering of the waterway and provide access to gates or valves in the waterway. Bulkhead
gates and modern stop logs are both constructed of structural steel with rubber seals and are virtually
identical in appearance. Stop logs are differentiated from bulkhead gates in that they employ more than
two sections and, when all the sections are installed, extend above the reservoir surface. Bulkhead gates
are made up of one or two sections and only cover the entrance to the waterway. Bulkhead gates and stop
logs are usually installed with a gantry or mobile crane.
draft tube. In the case of outlet pipes and penstocks, they are placed as far upstream as possible to allow
the complete unwatering of the waterway and provide access to gates or valves in the waterway. Bulkhead
gates and modern stop logs are both constructed of structural steel with rubber seals and are virtually
identical in appearance. Stop logs are differentiated from bulkhead gates in that they employ more than
two sections and, when all the sections are installed, extend above the reservoir surface. Bulkhead gates
are made up of one or two sections and only cover the entrance to the waterway. Bulkhead gates and stop
logs are usually installed with a gantry or mobile crane.
stop log installations.
Valves.
Valves, like gates, can regulate flow or act as guard valves to penstocks and outlet conduits. This
section will describe the most common valve types in use in Reclamation facilities.
1.
Tube Valves. Tube valves are used primarily as regulating valves in outlet conduits. The tube valve is
essentially a needle valve with the downstream needle omitted to eliminate the cavitation damage
experienced with normal needle valves. A hollow cylinder or tube is actuated by a mechanical operator to
seal against a valve seat on the downstream end of the valve. Like a needle valve, the fluid way converges
at the outlet. A tube valve is shown in
experienced with normal needle valves. A hollow cylinder or tube is actuated by a mechanical operator to
seal against a valve seat on the downstream end of the valve. Like a needle valve, the fluid way converges
at the outlet. A tube valve is shown in
2. Hollow-Jet Valves.
Hollow-jet valves are used as regulating valves and are similar in construction to a
tube valve. The closure member of the hollow-jet valve is the needle which moves upstream to seal against
its valve seat. The fluid way is not converging so that the discharge is in the shape of a hollow jet. The
hollow-jet valve can be operated either hydraulically or mechanically.
its valve seat. The fluid way is not converging so that the discharge is in the shape of a hollow jet. The
hollow-jet valve can be operated either hydraulically or mechanically.
hollow-jet valves.
3.
Butterfly Valves. Butterfly valves are most commonly used as guard valves on penstocks and outlet
conduits. They are normally used for flow regulation only if the head differential across the leaf is small.
The butterfly valve consists of a cylindrical or conical shaped body with a circular leaf, mounted on a
horizontal or vertical shaft, perpendicular to the fluidway. An external actuator, usually hydraulic, rotates
the leaf 90 degrees to fully open or close the valve. A butterfly valve is shown in
The butterfly valve consists of a cylindrical or conical shaped body with a circular leaf, mounted on a
horizontal or vertical shaft, perpendicular to the fluidway. An external actuator, usually hydraulic, rotates
the leaf 90 degrees to fully open or close the valve. A butterfly valve is shown in