06 Dec

What Is A Plug Valve And When Is It Used?

what-is-a-plug-valve-and-when-is-it-used

We’ve previously discussed how to select specific valves for improving production time and MTBF and thought it would be a good time to review one of the most simple and economical valves available: the plug valve.

Plug Valve Basics

 A plug valve is shaped like a cylinder or cone and can be rotated inside the valve body to control flow of fluids. Plug valves have one or more hollow passageways often placed horizontally to allow ease of flow through the valve when open. The most common type of plug valve is the 2 port model with an open and closed position. The two ports are usually located on opposite sides of the valve with one passageway leading from inbound to outbound and the stem and handle located on the top. A plug valve also uses a quarter turn valve, which is useful where quick and frequent operation is essential. The valve ends can be flanged, hub type, or butt weld.

Plug Valve Types and Their Uses

 Although there are many types of plug valves, there are four general categories, each with their own benefits.

1. Lubricated Plug Valve

 As the name suggests, a lubricated valve uses a lubricant usually made up of a base oil and viscosity improver (like amorphous or fumed silica) that is injected under pressure between the plug face and body seat to reduce friction and seal ports. Valve manufacturers generally recommend lubricant suitable for the process fluid, and the valves often must be resealed after only a few cycles, and in some cases, after every cycle. Considered a high maintenance plug valve, they are often used in applications that have infrequent operations. Lubricated plug valves perform well in processes that utilize fluids which carry mildly abrasive particles such as dirty upstream applications, gas pipeline systems that need bypass valves, and as blow-down valves on valve stations and kicker valves.

2. Non-Lubricated Plug Valve

This plug valve utilizes a tapered or cone-shape that acts as a wedge and presses a polymeric sleeve against the body cavity. The use of the sleeve reduces friction between the plug mechanism and body.  Non-lubricated plug valves are often used instead of lubricated ones in applications where maintenance needs to be kept to a minimum, such special services in sulphur, hydrogen fluoride, or where liquids could be trapped or solidify and potentially jam the valve. However, non-lubricated plug valves are limited by temperature and chemical compatibility of the non-metallic materials they are made of.

The three main types of non-lubricated plug valves are:

Lift-type plug valve

Elastomer sleeved plug valve

Fully lined plug valve

3. Eccentric Plug Valve

The design of this plug valve uses a half plug that is advantageous for applications needing a higher seating force with minimal friction from open to closed position. The torque seated valves also feature improved shut off capabilities. Eccentric plug valves are used for a wide range of flow control and isolation applications including clean and dirty water, sewage, sludge and slurries, air, and other services.

4. Expanding Plug Valve

 This complex plug valve uses multiple components that allow the valve to mechanically expand and give it a true double block and bleed function in one valve. The plug valve uses a mechanism that rotates between the open and closed position and protects both seals from the flow path. During rotation there is no contact between body and seals, and slips expand onto the body seat when the valve is closed to avoid causing any wear or abrasion to the seals. They are often used to prevent product contamination in applications that do not require a double isolation.

In conclusion, plug valves have a number of useful applications, and new technology and designs are sure to give them an even wider variety of applications within many processes. And if you need more information on different types of valves, check out this piece on check valves or the rest of the site.

 

Sourced by ekomeri.com

27 Oct

How Does a Water Check Valve Work?

  how-does-a-water-check-valve-work

    Check Valves

  • Check valves are devices that are installed in pipelines in order to stop the backflow of material. In many cases, the material flowing through the pipe is water, and the check valve keeps the water from flowing backwards in the pipe. They do not require any outside activation, but are rather designed with mechanisms that block the water from reversing direction at a certain point.

     Uses

  • Water check valves are used in several different devices, and they are advantageous for several reasons. For example, they stop flooding or overflowing in sump pumps and water heaters. They protect equipment in control valves, strainers and flowmeters. They also save power, because the backwards-flowing water would use up electricity even when the device was off.

     Types

  • There are several types of check valves that are installed in water-using devices, but they are all based on the same underlying principle. A ball check valve consists of a ball held in place by a spring. When the water flows forward, the spring contracts and the ball is pushed away from the opening of the valve. Therefore, the water can flow through the valve. When the water stops flowing, the spring pushes the ball back into the opening in the valve and stops the water from flowing backwards.Swing valves work in a similar way. Instead of a ball, swing valves contain a small door on hinges. When the water flows by the door, the door swings back on its hinges and allows the water through. When the water stops flowing, the door slams shut and stops any backflow from forming.Similarly, a split-disk check valve contains a metal plate that folds in half as the water flows past it. When the water stops flowing, the plate springs open and blocks the entrance of the valve.

 

 

Souced by ekomeri.com

29 Jan

DK-LOK Fittings and Valves for high-pressure equipment

dk-lok fittings valvesDK-LOK Fittings and Valves for high-pressure equipment.

  • Size Range: 1/16″ thru 1″
  • 316 SS, Carbon Steel, Brass, and Exotic Metals
  • Pressure Range: 1000 PSI thru 10,000 PSI
  • Full-Flow Quick Connects
  • Double Block and Bleed Valves
  • Swing-Out Ball Valves
  • Rising Plug Valves
  • Toggle Valves
  • Needle Valves
  • Relief Valves
  • Hose Adapters
  • Manifolds
  • Metering Valves
  • Purge Valves

Sourced by ekomeri.com