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 Manometer advice 
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Joined: Sat Sep 18, 2010 9:38 pm
Posts: 216
Location: Sydney, Australia
I am working with manometers right now.

The U-tube that was on this bench was designed for water, and that makes each 1" H2O equal to only ½" on the scale.

I'm used to SF benches that have reservoirs and oil of specific density less than water, and that makes the space between inches H20 closer to 1.2".

For me it's easier to get greater accuracy with 1.2" spaces rather than than ½" spaces so I'm going with the reservoir.

Image

There is a lot written in this forum about manometers and I think the general consensus was to use 3/16" tube, because the smaller 1/8" reacted too slowly, so that's another area you may have to look in to.

I'm also thinking about MMO and was wondering if anyone knows if MMO stains clear PVC tube?


Sat Apr 12, 2014 10:29 pm
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Joined: Wed Mar 30, 2011 8:26 am
Posts: 15
I made some progress with my bench, tried to upload a pic from iPhone but it is too big.
Anyways, time for a dumb question, I have my inclined monometer built and I understand how to use the scale generator but I'm not clear on one aspect. Is it best to place the reservoir low mod have zero at the bottom of the slope or place the reservoir high and have zero be the top of the slope? Does the question make sense??
Thanks for your help guys.


Wed Oct 08, 2014 7:30 am
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Joined: Wed Mar 30, 2011 8:26 am
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I think I got the picture to load.

Attachment:
flowbench4.jpg


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Wed Oct 08, 2014 10:28 am
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Joined: Fri Jan 08, 2010 3:35 pm
Posts: 1664
Location: Pennsylvania
Looks good!

Won't matter if it rises or falls, comes down to personal preference.

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Bruce

Who . . . me? I stayed at a Holiday in Express . . .


Wed Oct 08, 2014 12:23 pm
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Joined: Fri Feb 19, 2010 7:36 pm
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Location: Grantsville, Utah 45 min west of Salt Lake City
Brucepts wrote:
Looks good!

Won't matter if it rises or falls, comes down to personal preference.


As Bruce said it does not matter if it rises or falls. I ended up making mine fall and the only reason was when I had it rise and then you turned off the flow then some of the fluid would stay up in the tube. I think part of the reason was I was only using 1/8" i.d.tubing. You can also put a few drops of dishwasher rinsing agent in your water so it does not cling. I never tried that though. As for accuracy it was the same either direction.

John


Wed Oct 08, 2014 5:34 pm
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Joined: Wed Mar 30, 2011 8:26 am
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Got some more work done, but I'm getting more frustrated than a 3 legged dog trying to bury a turd on a frozen lake.

Could anyone tell me how it is even possible for my manometer to look like this when the vacuum is turned off and has been for days???
I even added onto the "Open" tube so that it hangs down to the same distance from the floor as my "Sampling" tube....thinking maybe it was showing me the difference in air pressure from the difference in height.... No dice.


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Wed Dec 10, 2014 1:40 pm
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Joined: Fri Jan 08, 2010 3:35 pm
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Location: Pennsylvania
check for fluid down stream stuck in your line

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Bruce

Who . . . me? I stayed at a Holiday in Express . . .


Wed Dec 10, 2014 2:50 pm
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Location: Melbourne, Australia
And check for trapped air bubbles.
With no pressure appled, there will be the same resting "weight" of fluid in each leg.
But there could be a big bubble lurking somewhere hidden down in the leg that is sitting up high.

The air lines should have no fluid traps, and the fluid lines no air bubbles.

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Wed Dec 10, 2014 4:11 pm
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Joined: Wed Mar 30, 2011 8:26 am
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Thanks guys, I will have a closer look.
Does this mean I haven't accidentally discovered a zero gravity machine.?.?

I better call NASA and let them know.


Wed Dec 10, 2014 4:21 pm
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Joined: Fri Feb 19, 2010 7:36 pm
Posts: 1628
Location: Grantsville, Utah 45 min west of Salt Lake City
One thing I would also suggest trying is some of that anti-spotting agent for dishwashers. It causes the water to sheet off and not stick. I helps the water to not stick in your tubes.

John


Wed Dec 10, 2014 7:10 pm
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