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Time for Hydro System to Reach Static Equilibrium

  1. Sep 28, 2011 #1
    I was tasked with redesigning our system to hydrostatically test valves. I had to incorporate a drip test downstream of the valve that would be the determining factor whether the valve was leaking or not. The system I came up with has 3/8" ID tubing (app. 10 ft) running from the downstream of the valve to a ball valve that connects to app. 1.5 ft of 1/2" tubing that loops vertically over the opening of a drain cup. My intention was to have the apex of the loop be the high point for the system. We flood the valve from the high pressure side evacuating all of the air. Then we close ball valve in b/t the 3/8" and 1/2" tubes. Next we close the valve. Now downstream of the valve should be charged with tap water pressure. I then open the ball valve and allow the water to reach equilibrium. If there is any leak in the valve as we build upstream pressure, the water will drip out of the 1/2" tube. The problem I am having is the TIME it takes for the system to reach equilibrium. The water quickly goes to the apex of the vertical loop but then slowly drips for up to 3 minutes.

    What changes can I make to help it reach equilibrium faster? The down stream of the valve is app. 37" from the ground. The tube goes to the ground till it reaches the control panel and raises to app. 39" for 2" to ball valve at 38". The 1/2" tube loop is 12" in height.

    I know I am missing some simple principle and would appreciate any help given.
  2. jcsd
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