Types Of Valve
Throttling Valves
| S.No | Types | Advantages | Disadvantages |
|---|---|---|---|
| 1 | Diaphragm valve | The interior of this valve is very smooth, and can be easily cleaned. | The valve leaks upon the failure of the diaphragm. |
| 2 | Butterfly valve | The rubber-lined valve is a good, cheap valve for all types of low pressure, non-critical services. This valve can also be lined with a resistant polymer for very corrosive service. | This valve Rubber lined valve has pressure limitations. |
| 3 | Needle valve | It gives good flow control; It can have very high pressure ratings. | It causes a high pressure drop & presents a greater risk of clogging due to entrained solids. |
| 4 | Pinch valve | This valve can be tightly shut off, and will even close when entrained solids are present in the flowing fluid. | The pressure rating of this valve is low. The compatibility of the hose material with the process stream is critical. |
| 5 | Globe valve | It can be used to modulate flow or to stay partially open to impose a certain pressure drop. | It passes flow in only one direction. |
| 6 | Stop check valve | Besides throttling like a globe valve, this valve also prevents reverse flow. | It’s design is more complex than that of globe and check valves. |
| 7 | Angle valve | Pressure drop is slightly less than a conventional globe valve. | It complicates the piping layout. |
| 8 | Y-pattern globe valve | It can throttle and is often used in high pressure service. | It complicates the piping design. |
On – Off Valves
| S.No | Types | Advantages | Disadvantages |
|---|---|---|---|
| 1 | Ball valve | Pressure drop is very low; it is suitable for handling erosive fluids & slurries. | Fluids that set up or polymerize could freeze the ball. |
| 2 | Plug valve | Pressure drop is fairly low; lubricated type is very good for slurry and catalyst service; plastic-sleeved plug is used for highly corrosive services. | Lubricated plug valve should be lubricated every time it is operated; plastic valves have a limited operating temperature (400F). |
| 3 | Hydrant valve | Useful in freezing climates. | ————- |
| 4 | Gate valve | Pressure drop is low; this valve weighs and costs less than other comparable size valves. | It is almost completely incapable of throttling. |
| 5 | Ram valve / Displacement valve | It is very useful for taking accurate samples of solid bearing streams. | These valves are custom designed to some exact, correct valve should be chosen for each application. |
Non – Return Valves
| S.No | Types | Advantages | Disadvantages |
|---|---|---|---|
| 1 | Split valve disc-check | It is generally the least expensive check valve in medium to large sizes Shutoff is somewhat better in this valve. |
It is not suitable for large material. |
| 2 | Lift-check valve | In small sizes, it is also one of the cheapest check valve. In large sizes, it can be used in pulsating flows |
The pressure drop is fairly high. |
| 3 | Swing-check valve | It will operate well whether installed horizontally or vertically. The body can be equipped with drain or bypass taps. |
It is large compared with & heavy other types of such valves. This valve is not suitable for pulsating flows containing entrained material. |
| 4 | Tilting-disc-check valve | The pressure drop is lower than that of the swing-check valve. |
IT is large & heavier than the swing-check valve. An over-sized valve is prone to flutter or slamming. |