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Unread 11-13-2002, 10:00 AM   #284
myv65
Cooling Savant
 
Join Date: May 2002
Location: home
Posts: 365
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Quote:
Originally posted by bigben2k
The pressure drop through a 3/16 opening, at 4 gpm (240 gph) is 11.7 feet (!) per inch of length. Flow speed is 46.5 fps (14.2 m/s).
Ben,

Pressure loss through a straight pipe is not the same as pressure drop through a point restriction, orifice, or nozzle. You could be close or off by a mile on your estimate. Unless you've got a chart from a reputable source showing P/Q for your planned nozzle then you're shooting blind.

You need to realize that in a straight pipe, you have as established flow pattern. In a nozzle or orifice, you have changes in the velocity profile that chew up energy. For sharp-edged, round orifice plates you can easily find equations and coefficients to predict P/Q. Once you deviate from that which has already been tested, you're kind of on your own, and simply approximating as a straight pipe can be quite misleading.
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