What do butterflies, gates, cones, balls, and sleeves have
in common?
They are all types of
valves used to control the flow of water through pipelines. Instead of our usual Photo Friday, we thought
we’d take the time to honor this under- appreciated, but extremely important,
feature in our water system. For the
record, a valve is a mechanical device that blocks a pipe either partially or
completely to change the amount of fluid that passes through it. And we at the SFPUC couldn’t operate much in the Hetch Hetchy Regional Water System without them.
Here at the Calaveras Dam Replacement Project, we are
installing all sorts of valves to
control the flow of water from Calaveras Reservoir for different purposes. Each
valve is specially designed to control water in a specific way without damage
to the surrounding pipeline. So, let’s geek out about valves!
Butterfly. A butterfly valve is a disk that sits in the
middle of a pipe and swivels sideways (to admit fluid) or upright (to block the
flow completely). It can also open partially to carefully calibrate the amount
of water flowing through the pipe.
We are using a 48-inch diameter butterfly valve to control
the flow of water to a temporary supply line for the Sunol Water Treatment
Plant.
The Sleeve. The Bailey valve sleeve valve reduces water
pressure and controls flow by diverting the water through multiple holes located
within the sleeve and discharging to the atmosphere or a body of water. The valve controls
flow by sliding one pipe called the gate over another pipe called the sleeve.
One of the Bailey sleeve valves installed in the building
that will provide a steady stream of water to Calaveras Creek.
The Ball. In a ball valve, a hollowed-out sphere (the ball)
sits tightly inside a pipe, completely blocking the fluid flow. When you turn
the handle, it makes the ball swivel through ninety degrees, allowing the fluid
to flow through the middle of it.
These
serve a similar purpose as the butterfly valve to calibrate the amount of flow.
The Cone. The body of the fixed cone valve is a tube with a
cone in the end welded with some grooves.
Another tube acts as the closure member. This slides over the body groves
in a linear movement to regulate until making contact against the seat of the
cone when the valve is fully closed.
This valve is not unlike your bathroom faucet,
only in our case, a whole lot larger.
The fixed cone valve is used to discharge water at high
pressure from reservoirs or full pipes into the atmosphere. The flow towards the exit of the valve is not
converging so that the discharge is in the shape of a hollow jet.
The fixed cone valve at Calaveras Dam in operation January
2017.
The Gate. Gate valves open and close pipes by lowering metal
gates across them. Most valves of this kind are designed to be either fully
open or fully closed. Meaning, unlike the butterfly or ball valves, gate valves
tend not to provide controlled flows of water, but either turn the flow
completely on or completely off.
Two of the gate valves installed in the water supply
discharge line from Calaveras Reservoir.
See you around the Valley!
