Showing posts with label water hammer. Show all posts
Showing posts with label water hammer. Show all posts

Tuesday, October 14, 2014

Advantages of a Wafer Check Valve

wafer check valve
Wafer check valve
(courtesy of Duo-Chek)
A wafer check valve is an excellent choice for applications where water hammer, mounting space and flow restriction are issues.

A wafer check is designed to be "sandwiched" inline between two pipe flanges in the piping system, adding very little additional weight or bulk to the piping layout. Wafer checks overall tend to be stronger, lighter, smaller, more efficient and less expensive than conventional swing check valves and are easier to install between standard gasket and line flanges.

Along with being lighter, easier to install and store, wafer check valves also offer the following advantages:
  1. Disc travel is short with less impact force caused by valve closing.
  2. The disc closes quickly with less water hammer pressure. Water hammer pressure is only 1/2 to 1/5 times of flange type swing check valve and flange type lift check valve.
  3. Low flow resistance.
  4. Horizontal and vertical installation available.
  5. Very low opening (cracking) pressure differential.
  6. More reliable due to lower impact forces, less water hammer.
Wafer check valves are available in many sizes, typically from 2” to 72”, in ASME pressure classes 125 through 2500 and API 6A and 6D pressure classes. DIN, JIS, BS, AS, and ISO standards are also available. Body styles include wafer, lug, double flanged and extended body. Wafer check configurations are available in retainer-less style, wafer, extended body wafer and lined. Typical body materials are cast iron, ductile iron, WCB cast steel, 316 stainless steel and other alloys. Common seating materials are EPDM, Buna-N, Neoprene, Refrigeration-grade elastomer, and Viton. The most common end connections are raised face, plain face, ring joint, weld-end, as well as hub-end.

Friday, September 26, 2014

Water Hammer in Steam Systems - Demo

According to Wikipedia, water hammer is defined as "a pressure surge or wave caused when a fluid (usually a liquid but sometimes also a gas) in motion is forced to stop or change direction suddenly (momentum change). A water hammer commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. It is also called hydraulic shock."

When improperly drained of condensate in a high pressure steam main fills with condensate and completely surrounds the steam, an implosion takes place causing devastating water hammer.

Draining condensate and keeping it away from the steam by using proper steam trapping equipment will prevent this from happening.

The following video, courtesy of Spirax Sarco USA, dramatically demonstrates the principle behind water hammer and its potentially devastating effects.