I think you might have problems Todd.  A pump off an aboveground tank I did
at a Loews 2 years ago developed "catching-up" issues.
We were transferring from normal to emergency and during the switchover the
supply bottomed out on start-up.  We had transferred after switch-over but
when the pump came up to speed, the main dropped to vacuum at the suction of
the pump.  I had a -30/30 gauge on the suction and she went from 4 PSI to -5
(I think) for about 30 seconds until the supply came back.  They had run a
10" right to the pump and put in 2 eccentrics, 10x8 and 8x6 to the 6" inlet.
I remember it had a 10" bypass with the jockey off either side and the
jockey controller showed pressure while we took a dive.  I'm kind of ham and
eggs to the science end of it but I think if you could reduce once, 10
diameters, reduce again, 10 diameters, you might avoid this.  Maybe
something else but it was a surprise fer sure.

Go Red Sox!!


Anybody ever have a problem going with this dramatic a reduction?

At 02:17 PM 5/26/2009, you wrote:
>Todd,
>
>Can you use a Victaulic #51 6" x 2 1/2" groove eccentric and connect to
>flanges using vic flanges?
>
>Jim Johnston, P.E.
>Fire Protection Engineer
>
>I have a situation where a 6" main from a tank is going to need to be
>connected to a 2-1/2" suction flange on a pump. The largest eccentric
>reducer I can get is 4 x 2-1/2. Can I back-to-back reducers without
>causing problems? Could I used a 6x4 90 on the suction line and then
>elbow back to the pump (with at least the minimum distance reqd)? Any
>other thoughts?
>
>Todd G. Williams, PE

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