Valves Flashcards
What kind of valve is this?
Plug Valve
What kind of valve is this?
Plug Valve
What kind of valve is this?
Vacuum breaker valve
A valve stem design is supposed to be “OS&Y.” What does that stand for?
Outside Stem and Yoke.
This indicates that the valve stem is a threaded part that raises and lowers the valve’s gate when the handle is turned. The stem is visible outside the valve body, while the handle remains stationary.
Line 1 represents which common control valve flow characteristic?
Quick opening
Line 2 represents which common control valve flow characteristic?
Linear
Line 3 represents which common control valve flow characteristic?
Equal percentage
Flow coefficient
What would be a good valve choice for a slurry or viscous fluid that needs to be diverted to multiple flow paths?
Plug valve
A valve’s _____________ reveals its capacity to allow fluid to flow through it, essentially indicating how much fluid can pass through the valve at a given pressure drop; a higher _____________ means a greater flow rate can be achieved with the same pressure drop, signifying a more efficient valve for fluid flow.
Flow coefficient
What kind of valve is this?
Relief Valve or Backpressure Regulator
What is this a picture of?
Anti-scald valve
What is this a picture of?
Sleeve valve
What is this a picture of?
Sleeve valve
What is the risk of using a butterfly valve in a long, high flow pipeline?
If the valve disc fails or comes loose and is pushed closed by the flow, there could be a powerful water hammer that causes damage to the valve and piping.
For a very long and large diameter pipeline, what are the best valve types to use?
Plug valves or sleeve valves are best. These valves cannot slam closed if they failure, which would result in a massive and damaging water hammer.
What type of valve is the blue valve in the picture?
Backflow preventer
For a backpressure regulator (BPR), as the valve stem opens, its Cv will _________________, and as it closes, it will ________________.
increase; decrease
What is the unit of a valve’s Cv?
gpm
What performance characteristics does a valve’s Cv relate?
A valve’s Cv can be used to relate its flow rate with a pressure drop across the valve.
One way this can be used is for sizing a back-pressure regulator. You can find the range of needed pressure drops across the valve, assuming a constant upstream pressure drop. From this, you can calculate a Cv range, which you can provide to vendors to get quotes.
How is valve turndown ratio calculated?
It is calculated by dividing the maximum flow rate of the by its minimum controllable flow rate. For example, a valve with a 10:1 turndown ratio can reduce flow to 10% of its maximum capacity while still maintaining accurate control.
The valve ___________ is the ratio of a valve’s maximum usable flow to its minimum controllable flow, indicating the range over which the valve can effectively control flow.
turndown ratio
A(n) _______________ is a small valve that controls the operation of a larger, main valve, typically used to control high pressure or flow by using a smaller, easier-to-operate signal.
pilot valve
