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Air Pressure Regulator velocity

  1. Mar 13, 2015 #1
    I have a pressure regulator that has working the range of outlet pressure 0 to 2 bar, inlet pressure 5 bar, flow rate of 600lit/min and the regulator has 1/4" outlet port (6.35mm). whole data is according to manual I have not tested the regulator. But for flow rate of 600lit/min the velocity must be around 335m/s in the 1/4" diameter, so is this the practical velocity in an outlet port?
  2. jcsd
  3. Mar 13, 2015 #2
    As noted in your other thread: no.

    First, I assume the outlet pressure range is 0 to 2 bar gage pressure, or ~14.7 - 43.7 psia (just using the "standard" atmospheric air pressure). Units are extremely important when discussing compressed air.

    Second, a 1/4 NPT fitting will not have a 1/4" inside diameter. Check on the actual specs of the equipment you are using/planning to use (for instance, a 1/4" npt pipe will have an inside diameter of 0.364", not 0.25") The specific fitting you are using will have manufacturer data, which you should look at, that will tell you the throat diameter.

    Third, you really need to specify of the 600 Lit/min is normalized volumetric flow rate, or actual volumetric flow rate. 600 Liters of air, when compressed to 2 bar (absolute) will be, volumetrically, 200 Liters. This is very important when calculating line velocities and friction losses.

    I want to reiterate: In no way is 600 Liters per minute a practical velocity for a 1/4 inch fitting. It may work for some specific scenarios, but it is neither practical, nor good design.
  4. Mar 15, 2015 #3
    I should point out that I meant it would be 200 Liters when compressed to 2 bar gage, not absolute as my previous post notes.
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