Are your downstream tappings far enough away from the orifice that the flow has fully expanded, rather than being a jet down the centre of the pipe. If it is far enough away, there will be some frictional losses. These could be measured by carrying out your tests without the orifice in place...
Depending on the size of the diffuser assembly, you could look at making a new free standing assembly with lifting equipment, connected to the blower via a flexible detachable hose so the whole assembly can be removed for future maintenance without draining the aeration lane.
It is also worth highlighting 25362's comment and that the Reynold's number includes a characteristic length, but that length can be anything. With pipes it is often the diameter, for non-circular pipes and channels, it can be the hydraulic diameter or hydraulic radius. If you are looking at...
The GPS won't stop the navigation arguments in the car. Now, you will have the GPS telling you to turn left, but your wife is telling you to turn right. Do you
a) Turn left and get to your destination, but suffer the wrath of your wife because you believed a silly computer rather than her...
Back when I was a student, we had to pay 5p for every print out we did. It focused the mind on not making "Check prints" of reports and drawings, but making sure everything was right first time, or as near to that as possible. I learnt it is possible to do all your reading, editing, checking...
When I have been involved with scale models of pump intakes, we have scaled everything to maintain a Froude number identical to the full scale sump. This was to make the vortices act in a similar manner in the model as in the full scale sump.
So I would guess, you would re-scale the designs...
I've seen drawings of a solution. I don't know how well it worked.
The problem causing manhole is made air tight, including an air tight manhole cover. A second chamber is connected to the manhole and a pipe is laid from the base of the second chamber to the air void in the manhole. The pipe...
All the pumping station design guides I have read state a preference for one suction per pump where possible, ideally with each suction in a separate bay in the pumping station. (I don't have my references with me now).
The single suction per pump eliminates multiple bends prior to the pump...
Just a small note on what katmar is saying, as the flow moves down the pipe, friction will be causing the pressure to reduce as he describes, but the conversion of velocity head to pressure will be making the pressure increase. If the distribution pipe is short, then the pressure at the dead...
http://water-works.wikidot.com/flow-distribution
Something I was working on a while ago and haven't finished, but it will give you an idea on how to size these.
From the client's perspective, they are not necessarily the experts, that is why they are employing you. They may not know what you need and therefore haven't commissioned the tests which you require.
As for record drawings, things happen within the client organisation which might make it...
Is the clean backwash water storage tank at a similar level or higher than filters? If so finding a pump will be a real challenge.
The water only rate seems about right.
The combined air/water rates seem low, but they depend upon the media being used. It does vary with temperature...
