Technical > Spud Miller's Cave

Barrel valve ? for Spud

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wideopen231:
Spud,

  I was playing around on your web site with calculators. Good news is they where almost dead on my SWAG so they must be accurate :D.   Question I have is . While checking numbers on N/A system and changed the BV from cube to K style the pressure made big jump.82 to 123 lb.s. Wondering why? Assuming this pressure calc. is for in front of barrel valve. It was a 8 line system .039 nozzles ,6.78 gpm pump 2.753 to the motor and .136 jet. Checked it with cpl ohter systems pretty much same results. Just got me wondering.

Spud Miller:

 Different metering valves change the system's "coefficient of flow" which changes the pressure in the system. The fuel has inertia as it moves through the system and as it changes direction, things get weird. Other things besides the valve affect this, but that's the biggest factor. Running the same system and changing the metering valve type will change the pressure.

When doing the math, we use a pressure correction factor get the pressure to calculate out to actual measured numbers. When you see the same numbers pop up for the different valves over and over again, system after system, it becomes apparent what those numbers should be. So, to have the online calculator be as accurate as possible, I built in those different valve types as a menu item and associated them with a number that is used in the calculations.

 Spud
 

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