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Difference between revisions of "Manual Valves"
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[[Category:Valves]]{{Knoppen}} | [[Category:Valves]]{{Knoppen}} | ||
[[File:Manual valves.png|thumb|right|Manual Valves]] | |||
[[File:Manual valves1.jpg|thumb|right|Manual Valves]] | |||
'''Manual Valve''' is a refill valve allows manual control of inlet port. The outlet valve allows manual control of the outlet port. Each package consists of the valve, fittings, and tubing to connect valve to the cylinder cap ports. | |||
==Types== | |||
Many different types of manual valves are used in industrial applications worldwide. The following are most typical of these valves used in steam systems, such as [[Ball Valves]], [[Butterfly Valves]], [[Globe Valves]], [[Gate Valves]], and [[Diaphragm Valves]]. | Many different types of manual valves are used in industrial applications worldwide. The following are most typical of these valves used in steam systems, such as [[Ball Valves]], [[Butterfly Valves]], [[Globe Valves]], [[Gate Valves]], and [[Diaphragm Valves]]. | ||
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The globe valve is suitable for use on a wide variety of applications, from flow rate control to open or close operation. | The globe valve is suitable for use on a wide variety of applications, from flow rate control to open or close operation. | ||
In this type of valve, flow rate control is determined not by the size of the opening in the valve seat, but rather by the lift of the valve plug . One feature of globe valves is that even if used in the partially open position, there is less risk of damage to the valve seat or valve plug by the fluid than with other types of manual valves. Among the various configurations available, needle type globe valves are particularly well suited for flow rate control. | In this type of valve, flow rate control is determined not by the size of the opening in the valve seat, but rather by the lift of the valve plug . One feature of globe valves is that even if used in the partially open position, there is less risk of damage to the valve seat or valve plug by the fluid than with other types of manual valves. Among the various configurations available, needle type globe valves are particularly well suited for flow rate control. | ||
Other points to consider about globe valves is that the pressure drop accross the valve is greater than that of many other types of valves because the passageway is S-shaped. Valve operation time is also longer because the valve stem must be turned several times in order to open and close the valve, and this may eventually cause leakage of the gland seal. Furthermore, care must be taken not to turn the valve shaft too far because there is a possibility it could damage the seating surface. | Other points to consider about globe valves is that the pressure drop accross the valve is greater than that of many other types of valves because the passageway is S-shaped. Valve operation time is also longer because the valve stem must be turned several times in order to open and close the valve, and this may eventually cause leakage of the gland seal. Furthermore, care must be taken not to turn the valve shaft too far because there is a possibility it could damage the seating surface. | ||
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Like ball valves, gate valves are not usually used to regulate flow. One of the reasons for this is because the valving element can be damaged when in the partially open position. Similarly, they also limit the pressure drop across the valve when fully open. However, setting the valve to the fully open or closed position requires the handle to be turned many times, which generally makes these valves have the longest operating times among those valve types mentioned here. | Like ball valves, gate valves are not usually used to regulate flow. One of the reasons for this is because the valving element can be damaged when in the partially open position. Similarly, they also limit the pressure drop across the valve when fully open. However, setting the valve to the fully open or closed position requires the handle to be turned many times, which generally makes these valves have the longest operating times among those valve types mentioned here. | ||
===Diaphragm Valves=== | |||
Diaphragm valves use a pinching method to stop the valve flow using a flexible diaphragm. They are available in two types: weir and straight-way. The most commonly seen of the two is the weir-type. This is because the straight-way type requires additional stretching of the diaphragm, which can shorten the diaphragm's life-span. | |||
One of the major advantages of using diaphragm valves is that the valve components can be isolated from the process fluid. Similarly, this construction helps prevent leakage of the fluid without the use of a gland seal as seen in other types of valves. One the other hand, the diaphragm becomes worn more easily and regular maintenance is necessary if the valve is used on a regular basis. These types of valves are generally not suited for very high temperature fluids and are mainly used on liquid systems. | |||
One of the major advantages of using diaphragm valves is that the valve components can be isolated from the process fluid. Similarly, this construction helps prevent leakage of the fluid without the use of a gland seal | |||