GATE VALVE
A sluice valve, also known as a gate valve, opens by raising a barrier out of
the way of the fluid. When completely opened, gate valves take up
relatively little space along the pipe axis and barely limit fluid flow.
In a pipeline, a gate valve is often used to totally shut off fluid flow or to give
full flow in the fully open position. As a result, it may be utilized in either the
fully closed or completely open position. A gate valve has a valve body,
seat, and disc, as well as a spindle, gland, and wheel for operation. The
seat and the gate work together to stop the passage of fluid.
When a gate valve is fully open, the disk is totally withdrawn from the flow
stream. When the valve is open, this property provides essentially minimal
flow resistance. As a result, a pressure drop across an open gate valve is
minimal. When the valve is fully closed, there is a 360° disk-to-seal ring
contact surface, ensuring effective sealing. When a disk is properly mated
to the seal ring, there is very little or no leakage across the disk when the
gate valve is closed.
TYPES OF GATE VALVE
Wedge Gates: A solid wedge valve may be fitted in virtually any location
and is suited for practically any fluid. It can also be used to turbulent flow.
When employed in high-temperature applications, solid wedges are prone
to thermal locking.
In addition to the primary force provided by fluid pressure, the tightening of
the stem creates a significant wedging force on the seats, which aids in
sealing. Due to reduced "rubbing" on the seats, the wedge-shaped gate
does not stick to the seat in the event of a large fluid differential pressure. It
also has a longer service life.
Parallel Expanding Gates: The mechanical expansion of the gate
provides sealing in expanding gate valves, which feature two slab gates
fitted together. The media can flow through both of the slab gate's cavities
when they are elevated. The outward mechanical expansion required for a
suitable seal is enabled by the upward push on one slab and the halting of
the second slab by a step in the valve body.
Slab Gates: Slab gates, also known as through-conduit gate valves, are
one-piece gates with a bore size hole in the middle. The bore is aligned
with the two seat rings in the open condition. This alignment results in a
smooth, turbulence-free flow. This one-of-a-kind design provides for little
system pressure loss, making it ideal for transporting crude oil and natural
gas liquids.
Knife Gates: Knife gate valves are used to control the flow of heavy fluids
and dry bulk materials. The gate is usually made of a single piece of metal
that is pointed. Because they pass the seat rings every moment they open
or close, these valves are self-cleaning.
GATE VALVE HAS BEEN CLASSIFIED INTO 3
WAYS
Solid wedge: This is one of the most frequent and oldest valves. It is
appropriate for any fluid and may be fitted in any position. In a turbulent
flow, it can also be employed.
The disadvantage is that it might choke because of thermal expansion
inside the pipe, making it more vulnerable to leaking. Due to the expansion
of the metal, the thermal locking wedge became trapped between the
seats.
Flexible wedge: This sort of disc is constructed in such a manner that it
becomes flexible and can withstand heat pressure by cutting incisions in
the disc's periphery.
The cuts come in a variety of sizes, shapes, and depths. It gains some
strength as a result of this. This method also improves seat alignment,
resulting in a tighter seal. The most significant drawback of flexible Gates is
that line flood tents gather in the disc.
Split wedge: It is made up of two discs that are parallel to each other and
are joined by a mechanical mechanism.
The disk can be of any type, including shift and parallel discs. Even after
the fluid has been heated, thermal blending cannot be achieved.
Gate Valve types Depending Type of Stem
Rising Stem Gate Valve: The OS & Y kind of gate valve is another name
for it (Outside steam and York). The stem rises when the valve is opened
and falls when it is closed, indicating the position of the gate valve. The
stem threads never come into touch with the flow media and are therefore
immune to corrosion and erosion.
Non-Rising Stem Gate Valve:The stem of a non-rising stem gate valve,
also known as an insider screw valve, is threaded into the gate. There is no
rising and lowering of the stem since the hand wheel and stem move
simultaneously. The flow medium comes into touch with the stem.
BONNETS
Bonnets: The interior elements of a gate valve are protected by a bonnet.
It is screwed or fastened into place on the valve body, forming a leak-proof
seal. As a result, it may be removed for repairs or maintenance. Gate
valves can have screw-in, union, fastened, or pressure seal bonnets,
depending on the application.
Screw-in Bonnets: Screw-in bonnets are the most straightforward to
make. They're commonly found in tiny valves and create a long-lasting
leak-proof seal.
Union Bonnets: A union nut holds union bonnets in place. The union nut
screws into the threads of the valve body and rests on the lower edge of
the bonnet. This design prevents the leak-proof seal produced by the nut
from deteriorating due to repeated bonnet removal. As a result, union
bonnets are frequently used in applications that need routine inspection or
repair.
BACKWATER VALVE
A backwater valve is a mechanism fitted on a sewer or waste pipe that
stops sewage or waste water from flowing back into the structure. The
valve is a physical barrier that enables sewage to flow in one direction
while preventing backflow from plumbing fixtures such as toilet floors,
shower sinks, bathtubs, and drains.
TYPES OF BACKWATER VALVE
Horizontal Backwater Valve: To avoid backflow, a backwater valve with
an internal check member and a manual gate valve is meant to be put in a
horizontal drain line.
Terminal backwater Valve: A backwater valve with a check member to
prevent backflow that is put at the discharge end of a horizontal drain line.
Combination Floor Drain: A backflow-preventer floor drain with an
internal check member.
Vertical or 90-Deg Backwater Valves: Backwater valve for vertical
pipework, such as downstream of a P-trap or storage tank.
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