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Subject: RE: [FlyRotary] Re: EWP check valves
Date: Mon, 20 Oct 2003 18:57:02 -0400
Message-ID: <0B27ED95697C4D4CBC82D79E790FE567086FA7@exchange.rfgonline.com>
Thread-Topic: [FlyRotary] Re: EWP check valves
Thread-Index: AcOXUU+pR5Osl6hARgq+alch4JeP1gACzsWQ
From: "Robinson, Chad" <crobinson@rfgonline.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

> Ken wrote:
>
> > The spring loaded ball valve will be to restrictive, better with a
> > flapper valve.
>
> And Rusty responded:
>
> The listed "CV" rating is defined as: "the amount of water (in gpm) =
that
> will pass through a fully open valve at 1 psi with 1 specific gravity =
(60=B0 F)."
> Since the rating for the 1.25" valve was 44, and you'll have one of =
these for
> each pump, it seems reasonable to me.   =20

Yeah, sorry, I should have mentioned that. These things will pass way =
more water (44gpm) than the EWP can pump (88lpm), and that's only at =
1psi. The formula to calculate the actual value is:
  gpm =3D Cv * sqrt(pressure drop / specific gravity)

The specific gravity for water is 1, so at 1psi you get Cv * 1, or Cv. =
At higher pressures you get more.

You SHOULD know that it does impose a small amount of flow resistance, =
but certainly much less than a right-angle bend so it's probably not =
worth even calculating.

By the way, their Web site does note that for this particular =
swing-check valve, it should be mounted horizontally, or if the flow is =
vertical, it should be mounted so that the flow is UP. That may matter =
to you depending on how you arrange your plumbing.

Regards,
Chad