Gate valve is a valve that is most widely used one. If I do not know how I try to look at the water meter home. (Hope that I have used tap water), which pipes water to separate from the main pipe. Before the meter will be off valve - open one. This valve is a gate valve (the valve, we heard it was a "gate"), perhaps it may install a gate valve on the output of the meter as well. However, some of which will install the check valve (the valve between the reverse flow) into the outlet of the meter. The gate valve must be installed before removing the meter from the meter to be removed. (Whether to repair or cut off the water because they do not pay the water bill).
The structure of the valve will be part of the disk (disk or a gate, see Figure 1) that is slightly larger than the diameter of the pipe. Up - down in the direction perpendicular to the direction of flow. When the valve is in closed position. The upstream pressure of the fluid will push the disk to lean with the body of the valve on the downstream side of the sealed fluid to flow through.
Advantages of the gate valve is wide. (Measured in the direction of flow) is not much space to install a small pressure loss (pressure drop) across the valve is very low when the valves fully open. Suitable for the type - open This valve is not suitable for use in flow control because the relationship between the length of the valve opening and flow rate is not good. (That is, some of the valve to move a little so that the flow rate changes. However, some of the valve to move a lot, but the flow rate changed only slightly) and is not suitable to open narrowed or slightly (crack opening) as the hand wheel, just not one we just feel that the fluid begins to flow through it. stops rotating. (You know it occurs when the fluid was flowing through a small opening between the seat ring below the disk), because while the valve is opened slightly. Fluid flows through a very high speed. And low pressure (pressure head is changed to velocity head) will cause the disk to vibrate violently enough to cause the disk or seat of the body that cause wear. This will not be able to close the valve to close again.
Figure 1, the gate valve type (left) Rising spindle gate valve, and (right) Fixed spindle gate valve of the core or stem is responsible for part of the disk (the that across the flow) on (to open) or down (to close) valve is visible rising spindle axis appeared to protrude from the center hole on the hand wheel to rotate the valve to open. You can see the sink into the hole in the middle of the hand wheel on the valve to close by the hand wheel is located on the same level. The valve fixed spindle and the disk is moving up - and down the spiral of the stem inside the bonnet on a rotating spindle which is not that he handed out roughly when the valve is in a position to open the valve rising spindle, it has many advantages. Just look what I know now that the valve is open or closed position. By the knowledge that emerges from the middle of the hand wheel lubrication and can be easily helix
Master Lock 482 Rotating Gate Valve Lockout
In addition, the pressure between the upstream and downstream of the valve in the closed position is very different. The valve opening can be difficult. Because the upstream pressure will press the sheet firmly against the body of the valve plate to move the disk moves in a direction perpendicular to the pressure is difficult. (I took one or more people standing on the mat. Then you pull the mat out. He failed, but if you have 10 people to stand up on the mat and then give you a surge of new mats. This time, you can not do that because there is not enough) in this case, the globe valve closing - the better.
Another type of event that caused the problem with the gate valve is used to mix liquids with suspended solids. (One example in the petrochemical industry and slurry from the slurry polymerisation. For example, in PE PP plastic, etc.) The problem occurs when the valve is located between the solid particles are left at the bottom of the disk of the valve seat and the valve does not close it. In this case, the ball valve is more appropriate.
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