They come in many shapes and sizes, with names like butterfly, gate, cone, ball, and sleeve. And the SFPUC couldn’t operate its water system without them.
A valve is a mechanical device that blocks a pipe either partially or completely to change the amount of fluid that passes through it. Each valve is specially designed to control water in a specific way without damage to the surrounding pipeline. There are hundreds of them throughout our system.
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.
The SFPUC is 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.
The New Calaveras Dam utilizes one of these to release a steady stream of water into Calaveras Creek to keep the aquatic habitat healthy.
The Ball. In a ball valve, a hollowed-out sphere (the ball) sits tightly inside a pipe, completely blocking the fluid flow. When turning 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 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.
Thanks to these lowly valves, we can operate our system safely and efficiently.