Digital Manometers Bench Reads inconsistent flow measurement

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ebug
Posts: 6
Joined: Thu Feb 25, 2010 6:30 pm

Digital Manometers Bench Reads inconsistent flow measurement

Post by ebug »

All,
I just started using my bench and have decided to use a pair of inexpensive digital manometers.

Last night I was comparing the flow numbers of a pair of 2-stroke reed valve assemblies. I tested both candidates at 12", 16",and 20". As expected the delta was greater at the higher depression numbers. When I converted all the numbers to 28" I found that the actual flow at 28" was higher as the test depression pressure went up. I was expecting the numbers to be fairly consistent once converted to 28".

Can someone help me pinpoint the problem in my assumptions please.

FYI,
I am using a modified version of the spreadsheet located on this site. The mod is to include the math on each row so I can build a chart. I have triple checked the formulas and believe I have transcribed them verbatim.

Thank you in advance,
Rob
ebug
Posts: 6
Joined: Thu Feb 25, 2010 6:30 pm

Re: Digital Manometers Bench Reads inconsistent flow measure

Post by ebug »

This is a screen shot of what I am referring too.
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ebug
Posts: 6
Joined: Thu Feb 25, 2010 6:30 pm

Re: Digital Manometers Bench Reads inconsistent flow measure

Post by ebug »

Well after a few days rest I have it all sorted and I feel like a klutz.

I was trying to look at this like I had a fixed restriction in the reed plates, but as we all know the reeds bend as these the depression increases. That creates a larger flow window. That is why my @28 numbers were getting higher.

Rob
Brucepts
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Re: Digital Manometers Bench Reads inconsistent flow measure

Post by Brucepts »

As you found out taking a day or two can sometimes make things "click" in your brain and you get that "ah-ha" moment!

I've done that more than a few times working on a flowbench issue. Rick can attest to that with my lack of willingness years ago to leave the pitot style flowbench for the orifice design. Took me awhile until the orifice style "clicked" in my brain!

Glad you figured it out!
Bruce

Who . . . me? I stayed at a Holiday in Express . . .
86rocco
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Joined: Thu Mar 04, 2010 9:01 pm

Re: Digital Manometers Bench Reads inconsistent flow measure

Post by 86rocco »

You've not only answered your own question, you've come up with a method of comparing and evaluating different reed valves.

Anyways, it's gratifying to see that my old spreadsheet is still making the rounds and being put to good use.
Brucepts
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Re: Digital Manometers Bench Reads inconsistent flow measure

Post by Brucepts »

86rocco wrote:You've not only answered your own question, you've come up with a method of comparing and evaluating different reed valves.

Anyways, it's gratifying to see that my old spreadsheet is still making the rounds and being put to good use.
Has been indispensable to the forum users!!!! :) :) :)
Bruce

Who . . . me? I stayed at a Holiday in Express . . .
86rocco
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Joined: Thu Mar 04, 2010 9:01 pm

Re: Digital Manometers Bench Reads inconsistent flow measure

Post by 86rocco »

Brucepts wrote: Has been indispensable to the forum users!!!! :) :) :)
Thanks Bruce.
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