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Posted:
Thu Nov 18, 2004 9:08 pmby bruce
Ok, I was at an auction this past weekend and scored 2 Ametek Lamb blowers model number 14786 they are 7.5" blowers. I want to set them up in a box that attaches to the side of my existing flowbench for R&D purposes.
Anyways my concern is vacuum in the box with "no-flow" conditions. I'd like to design a vacuum break into my box to keep it from over vacuuming (is that a word?) my idea is to use a peice of round plate calculate the surface area and figure out what the spring tension should be and install it on the other side. Like a big ole valve and seat setup where the vacuum works on the surface area of the plate to open it up to relieve the pressure inside the box. I'd make it adjustable so I could set it to the pressure I deem would keep my box from imploding.
Does this all make sense? Does it sound like it would work? Is there an easier way? Ideas or thoughts?
Posted:
Fri Nov 19, 2004 12:14 amby 2seater
I would think the box could be pretty small for only two vacuum motors, so it would be inherently stiff to prevent implosion. I experimented with one of my vacuum motors, listed @ 91" of dead water lift. I just plugged the inlet opening with a plate and a commom Hg vacuum gauge used for automotive testing and it indicated about 7" of mercury, or approx. 3.5 psi. The reverse popoff valve sounds interesting and could be used to prevent the fluid being pulled from the manometer if the inlet were accidently plugged, plus if the spring tension were adjustable, I would think it might also be used for adjustment of the base vacuum reading, if it didn't flutter.
Posted:
Fri Nov 19, 2004 6:56 pmby 84-1074663779
The pressure limiting valve sounds like an excellent idea, a light gauge plate and spring might tend to flutter but if the opening pressure setting is high enough, it should never open during normal operation. It is only a safety system, so flutter does not really matter.
Things are always easier to make and seal if they are under vacuum, the joins all compress and tend to close up. Pressure tends to burst things and open up small difficult to find and fix leaks. Never underestimate what a few tons of air pressure can do to wood screws ! A safety pressure limit system is an excellent idea, the flow area need not be very large to be effective.
Posted:
Fri Nov 19, 2004 9:47 pmby bruce
My intent would be for the valve to be a vacuum break and would be set well above my testing pressure. It would only come in to play when there would be no flow through the bench to keep the blower box from imploding.
I started on a box today for the new blowers to try them out. I think I'll come up with something in the way of a valve and see how it works. I'll post some pics when I get it done.
Posted:
Fri Nov 19, 2004 10:18 pmby 2seater
What about a cone or tapered shape to the spring loaded plug? I would guess it may be more stable as air flows around it. Clones of the Superflow benches use stainless steel bowls to adjust the air flow for smooth transitions.
Posted:
Fri Nov 19, 2004 10:56 pmby bruce
This valve is simply to keep the vacuum from exceeding the box/bench construction and imploding it. It does not control any airflow other than that. No airflow will flow around it unless the vacuum level exceeds its set value. This value will be well above the testing pressure so airflow will not be a concern.
I have a gate valve in my piping that controls flow depression when testing a part. This is just a safety valve idea . . .
Posted:
Sun Nov 21, 2004 12:33 pmby bruce
Ok had some time to take a pic or two of my newest addition to my R&D flowbench.
I am able to flow around 20" now using these 2 blowers. Testing on a 1.380 valve dia. I have some vacuum leaks I need to find so I'd say with leaks closed up I should be able to "see" depression of 25" and flows around125 cfm's? The blowers are Ametek/Lamb model number 14786 and are 7.5" dia.
One thing I know is it sounds like a Jet engine in the shop now!! I'm not much of a carpenter so I didn't enclose the motors in a box yet. I didn't want to waste alot of time to just try them out. I have plans for a different blower for my bench down the road.