Guide to Gate Valves

Cut off flow with the right gate valve for your company's application

By W. Aiman Mueller

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Gate valves are also known as slide valves or knife valves. A gate valve consists of a flat closure piece that slides into place. The inside diameter of the valve body is often very close or identical to attached pipes, so a fully open slide gate valve causes only a negligible pressure drop. Gate valves are very effective shut-off valves.

Since the gate inside an industrial gate valve takes a linear path through the center of the valve it can cut through thick fluids. This makes industrial gate valves ideal for situations that involve slurry or viscous fluids, like oils or grease.

Here are the main types of slide gate valves:

1. In a parallel gate valve, a flat disk divides two parallel seats to achieve shut-off.

2. In a double-parallel gate, two disks with an inclined plane lower between two parallel seats. Once the disks are fully down, the inclined plane presses the disks against the seats.

3. The two seats of a wedged-shape gate valve are inclined and the disc is somewhat mismatched to achieve higher sealing pressure.

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Shop quality gate valve manufacturers and gate valve suppliers

Gate valves are manufactured with a variety of materials. Also, keep in mind that gate valves are not generally built for high pressure applications, so their pressure ratings are not always published. Lastly, there are so many gate valve manufacturers and gate valve suppliers that comparing gate valve prices is a must.

I recommend: Grainger has a wide selection of gate valves from small to medium sizes. For larger industrial knife gate valves, see Tyco Flow Control, which carries much heavier-duty valves.

Be careful when choosing gate valves to throttle flow

Gate valves are not the best device if you need to achieve a full range of flow regulation. The disc can vibrate during flow, which erodes the seats and even the disc itself. However, there are some applications that involve infrequent throttling where knife valves may still be the right choice.

I recommend: Look to suppliers of gate valves that carry the heaviest-duty knife valves. NICO Valves Corp. manufactures some serious gate valves, but their selection is limited and somewhat specialized. Also, take a look at Clarkson valves, like the ones on Tyco's website, which pressure rate up to 300 p.s.i.

Maintain and repair your industrial gate valves

Check your valves regularly for leaks or corrosion. Planned repairs are much cheaper than sudden breakdowns.

I recommend: Davis Valve has an installation and maintenance manual for their products on their website, as do some other suppliers of gate valves. However, you may want to call in some help. That's where a company like Furmanite comes in, which services heavy industrial applications.

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