Rocker isolation valves are generally smaller and more compact than diaphragm isolation valves, making them well suited for certain applications with specific space limitations.
Some of the other benefits of rocker style isolation valves are that they can be relatively inexpensive, with low internal volume and fast actuation times. However, despite their low internal volume, rocker valves have more dead volume and are less well swept than diaphragm isolation valves.
This causes them to have more carryover, which can be problematic for certain applications, as can an increased risk of cross contamination. Another factor to consider is that rocker valve designs include elastomeric seals, giving them a shorter lifespan and making them less chemically compatible than some diaphragm style valves. This type of isolation valve is most frequently used in industry for dispensing materials or to drive other larger valves. A diaphragm isolation valve—also known as a "membrane valve"—is a solenoid-operated device that uses a diaphragm that extends and retracts to seal the valve seat and isolate the flow path.
Compared to the rocker style, diaphragm style media isolation valves feature much longer life, are better swept and have much less dead volume—some as little as zero. Another benefit of this type of isolation valve is that the diaphragm design can be made from non-elastomer materials such as PTFE, which eliminates the need for seals, providing increased chemical compatibility.
This type of isolation valve can be constructed from inert materials, including an entirely inert fluid path. This makes diaphragm style isolation valves ideal for applications involving corrosive media.
When selecting this type of isolation valve, it is important to consider the diaphragm material and the media that will be used.
The high flexibility of these types of materials allows them to tolerate small amounts of fine particles, but common chemicals such as methyl alcohol or ammonia can damage these types of diaphragm membranes.
For chemotherapy treatments or other applications that involve corrosive media, specially designed non-elastomeric diaphragm isolation valves are available with more robust membrane materials, such as PTFE. When choosing a valve for use with corrosive media, it is important to identify that all wetted materials are inert.
For the longest lifespan and lowest risk of cross contamination, the flow path and all wetted areas of the valve should be constructed of an inert material that is compatible with the media that will be used.
A pinch valve is a device that opens and closes the flow path by pinching a removable, disposable tube. Although not formally considered isolation valves, pinch valves perform an identical function by isolating the valve mechanism from the media through the use of this disposable tubing.
Pinch valves may be operated by electricity, air pressure, or manual operation. The operation power of electrically-actuated pinch valves varies greatly according to the application and size of the valve. Most draw anywhere from 0. They are also able to deliver more force, making them a good option for applications that require the use of firmer higher durometer tubing. Another advantage is size—since pneumatically piloted units are able to provide more force, the size can be scaled down to fit into smaller, more compact spaces.
For medical applications, pinch valves typically use medical-grade silicone tubing. If chemical compatibility is an issue other materials may be used, provided they match the pinch mechanism's original durometer and O. For example, media containing chloroform, ether, and some common alcohols will dissolve silicone tubing, however Neoprene tubing can be safely substituted. Indicating valves are those valves that provide an easily distinguishing visual method to determine the open or closed status of the valve.
A rocker isolation valve is a solenoid operated tool that utilizes a rocker system that rotates to seal the seat of the valve and isolate the flow route. A pinch valve is a device that, by pinching a removable, disposable tube, opens and closes the flow route. Although not officially deemed isolation valves, by using this disposable tube, pinch valves conduct an identical role by isolating the valve system from the media.
Like all other types of isolation valves gate valves are also a isolation valve. Gate valves are multi-purpose bi-directional shutoff valves for commercial and industrial applications. Home Forum Tool Contact Us. Residential plumbing systems both water and gas 4. Nuclear reactors 5. Oil and gas wells 6. Chemical plant 7. Oil production plant. Gate, globe, ball, butterfly, play, and diaphragm valves are all types of stop or isolation valves.
These all valves used for isolation of fluid in a pipeline. Mainly two types of valves: 1. Control valves, which are defined as manipulating a flowing fluid to keep process variables as close as possible to the desired set point; and 2. Modern systems typically use quarter turn valves either handle or screwdriver operated that are unobtrusive when installed in the pipework.
When the handle or screwdriver slot is in line with the valve, the valve is open; when they are at right angles, the valve is closed. Yes,Gate valves GV are specifically used in isolation applications in various piping systems. And they can be fully opened or fully closed. Gate valves, like other isolation valves such as ball valves, plug valves, piston valves, diaphragm valves, butterfly valves, and pinch valves, are isolation valves.
A globe valve can be used either as an isolation valve or a regulating valve, depending on its trim. Globe valves are primarily designed to regulate flow in the partially open position, while gate valves are designed for the fully opened or fully closed position. Source :- Wikipedia.
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