Hi all, I have been having a problem with my inclined manometer and was looking at the Dwyer catalog. I notice that they put the pressure on the well and "blow" the liquid DOWN the incline. Meriam, on the other hand, blows the liquid UP the incline from their well. Does anybody know if there is a preferred (other than by manufacturer) direction (and why)? Thanks in advance!
Doug
Inclined Manometers - Should they go up or down?
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by Tony » Mon Oct 22, 2007 4:45 pm
Either way works perfectly o/k.
It depends on what you are used to I suppose, but personally I prefer to see the fluid rise upwards to show an increase in the numbers. But there is nothing at all wrong with doing it the opposite way.
It depends on what you are used to I suppose, but personally I prefer to see the fluid rise upwards to show an increase in the numbers. But there is nothing at all wrong with doing it the opposite way.
Also known as the infamous "Warpspeed" on some other Forums.
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by ThomasVaught » Mon Oct 22, 2007 5:46 pm
The only issue I have seen between the two manometers is that the Merrium unit has a large well with a given amount of air above the
well fluid. (Example the well is a 1.5" x 5" or 7.5 Inches of area).
If the well height is 3" tall and the fluid is basically at the "Zero Point"
with 2" of fluid then you basically have 7.5 Square Inches of air above
the fluid. Now we all know that air is compressible so there is some
air pressure change on the delta P across the manometer. Personally
I think this can be calibrated out but you also have a large volume of
air that is now mixing with the fluid in the well. This can cause air
bubbles in the measurement tube.
The Dwyer manometer pushed against a very small area of water in
the inclined portion of the manometer as the cork check valve takes
up a bunch of the volume in the check valve cavity. Very little air goes
into the inclined part of the manometer.
Just my opinion.
It also seems like you have more ability to zero out the manometer as
the fluid will be somewhere on the inclined portion and once you identify that location a simple slotted scale easily sets the zero point. I have a
much harder time with a well located on the right with the fluid rising
to the left vs a system where the fluid always moves from left to right in your eyesight.
Tom V.
well fluid. (Example the well is a 1.5" x 5" or 7.5 Inches of area).
If the well height is 3" tall and the fluid is basically at the "Zero Point"
with 2" of fluid then you basically have 7.5 Square Inches of air above
the fluid. Now we all know that air is compressible so there is some
air pressure change on the delta P across the manometer. Personally
I think this can be calibrated out but you also have a large volume of
air that is now mixing with the fluid in the well. This can cause air
bubbles in the measurement tube.
The Dwyer manometer pushed against a very small area of water in
the inclined portion of the manometer as the cork check valve takes
up a bunch of the volume in the check valve cavity. Very little air goes
into the inclined part of the manometer.
Just my opinion.
It also seems like you have more ability to zero out the manometer as
the fluid will be somewhere on the inclined portion and once you identify that location a simple slotted scale easily sets the zero point. I have a
much harder time with a well located on the right with the fluid rising
to the left vs a system where the fluid always moves from left to right in your eyesight.
Tom V.
- ThomasVaught
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- Joined: Fri Jul 06, 2007 9:06 pm
by 115-1172523331 » Mon Oct 22, 2007 10:24 pm
Tom, In an earlier post, I think it was Tony who proposed that the well area SHOULD be much larger than the tube to minimize the well drop due to the raise in the tube. If I remember right, this was to eliminate the correction required. Is there a way to do this and eliminate the problem you just discussed? (I discovered a crack in the back side of my well and have to replace it anyway.) -- Doug R.
- 115-1172523331
by ThomasVaught » Tue Oct 23, 2007 11:13 pm
You can still do the large well deal but put it on the outlet side of the manometer (The non push side).
It does not matter if the well is very large and the well goes down
very slightly as it would with the merrium set-up or if the well goes
up very slightly.
If the well goes up very slightly you are actually pushing the fluid
through the small tube with little air being pushed into the fluid
and the the large volume of air above the large well is just being
pushed out the outlet line.
Tom V.
It does not matter if the well is very large and the well goes down
very slightly as it would with the merrium set-up or if the well goes
up very slightly.
If the well goes up very slightly you are actually pushing the fluid
through the small tube with little air being pushed into the fluid
and the the large volume of air above the large well is just being
pushed out the outlet line.
Tom V.
- ThomasVaught
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- Joined: Fri Jul 06, 2007 9:06 pm
by ThomasVaught » Thu Nov 22, 2007 8:02 pm
If you use electrons that are trained to lean over.
It is very difficult to find previously trained electrons though.
They must be conditioned with a device created by a scientist
named Chubacca.
Tom V.
It is very difficult to find previously trained electrons though.
They must be conditioned with a device created by a scientist
named Chubacca.
Tom V.
- ThomasVaught
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- Joined: Fri Jul 06, 2007 9:06 pm
by 106-1194218389 » Thu Nov 22, 2007 8:27 pm
btw Everybody, part of my thanks on this USA thanksgiving, sorry I missed Canada's, is having found this forum and received of your input. Many mysteries have been revealed and the light bulb has come on. It won't be long until I start my build. I am going to be doing some testing with a home made inclined manometer this week end.
John - btw Tom do you have Chubacca's number
John - btw Tom do you have Chubacca's number
- 106-1194218389
by 106-1194218389 » Tue Dec 11, 2007 12:47 am
Well I am in need of help. I think I am lost or do not understand something. I built an inclined manometer similar to what Ed (Rocco) built. The scale is 36" long with 12" rise from the 100% (36") to the 0% (0") mark. I used two syringes on the same end as Ed's with both having a 5/8" id and one syringe on the push side of the manometer. I also used his spreadsheet to figure out the scale. I was trying to be careful and pay attention but I am getting readings I do not think are accurate. I am flowing through a 1.670" square edged orifice. I have flowed it on a flow bench and it flows 208.7 cfm which works out to a .633 cd I think if I remember correctly. The only possibility for error is I am flowing it mounted in a 4" PVC tube 2 feet on each side of the orifice and 1/4" cell flow straightner. The head I am flowing flows 233.4 cfm at .500 lift on a Super Flow bench. Flowing it through this tube I am also using a Performance Trends black box going to Port Flow Analyzer software and reads the same as the flow bench at .500" lift. My inclined manometer only reads 79.5% which would be 79.5% of 208.7 according to the orifice flow. That would be 165.9 cfm. Ok I am lost. Can you shed some light anyone. I know flowing in the tube would be a little off but WOW! If you need to know any particulars that I have not listed please let me know.
John
John
- 106-1194218389
by Tony » Tue Dec 11, 2007 3:49 pm
O/k Jfholm, here is something to try.
Construct another 1.67 inch flat orifice plate as identical to your measurement orifice as you can make it. Place this directly over the test hole, and pull some air through it.
Now you have two identical orifice plates flowing exactly the same mass of air (assuming no leaks). The pressure drops should be exactly the same if both orifices have the same flow coefficient. But they will not be.
The test orifice on the bench top has undisturbed up stream room air flowing into it, the measurement orifice is located in a fast flowing pipe. They will behave very differently. How much different they turn out to be, should give you some insight in your anomaly.
Construct another 1.67 inch flat orifice plate as identical to your measurement orifice as you can make it. Place this directly over the test hole, and pull some air through it.
Now you have two identical orifice plates flowing exactly the same mass of air (assuming no leaks). The pressure drops should be exactly the same if both orifices have the same flow coefficient. But they will not be.
The test orifice on the bench top has undisturbed up stream room air flowing into it, the measurement orifice is located in a fast flowing pipe. They will behave very differently. How much different they turn out to be, should give you some insight in your anomaly.
Also known as the infamous "Warpspeed" on some other Forums.
- Tony
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- Joined: Sat Dec 03, 2005 12:34 pm
- Location: Melbourne, Australia
by 106-1194218389 » Wed Dec 12, 2007 12:05 am
Thanks for the input and food for thought guys. Also a discription of the tube. It has a 4" id and has 2 ft of tube on each side of the orifice. There is a flow straightener honey comb in the each end of the tube. my pressure taps are about 1/2" away from the orifice plate on each side and flush with the inside of the tube. Any suggestions on the pressure tap placement or should that be ok?
John
John
- 106-1194218389
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