PTS Flowbench Forum

Let's say my digital manometer breaks and I don't have a water manometer can I hook up my hand held digital manometer that reads inches of H2O to where the inclined manometer would connect and just take the reading in inches and use Ed's program to figure out the percentage from the inches of H2O reading. On the inclined compensation part of Ed's spreadsheet it shows a " in H2O reading for every percentage reading so I am assuming I could do that. Albeit not nearly as convenient and nice as using a digit manometer like Bruce's. But just in case of an emergency if you had to get a head done.

John

Hey John, is that your way of asking me to tweak my spreadsheet to make it more convenient to use under those circumstances?

BTW, it's a super simple calculation it doesn't really require a spreadsheet, it's easy enough to do with a calculator.

Let's say your orifice is rated at 300cfm@16" ,
You simply divide your digital manometer reading by 16, take the square root of the result, then multiply that by 300

86rocco wrote:Hey John, is that your way of asking me to tweak my spreadsheet to make it more convenient to use under those circumstances?

BTW, it's a super simple calculation it doesn't really require a spreadsheet, it's easy enough to do with a calculator.

Let's say your orifice is rated at 300cfm@16" ,
You simply divide your digital manometer reading by 16, take the square root of the result, then multiply that by 300

no need to tweak the spreadsheet. I would just take my reading and if I had a 300 cfm plate I would read the digital manometer and if it said 8.5" H2O I would look that up on the spreadsheet and see that reading is 73%. Then I would just calculate what 73% of 300 was. Wouldn't that work?

It's not quite that simple John, first you need to make sure the sheet is properly configured, scroll down the sheet to 100%, check to see what the Δp at that point is, if it doesn't match the calibration point of the orifice, in my earlier example that was 16", you'll need to reconfigure the spreadsheet until they match. The easiest way to do this is configure the sheet for a simple vertical U-tube manometer i.e. make the reservoir and tube i.d. the same then set the scale length match the calibration point, set the vertical height to the same value. At that point, you can use the sheet in the manner you suggested.

Ed,
Thanks! very well explained and Malvin and I got the same answer so we must understand what you are teaching us

John

jfholm wrote:Ed,
Thanks! very well explained
John

Except I made a stupid mistake

The scale length and vertical height need to be set to one half the calibration point. Or alternatively, set the scale length and vertical height to match the calibration point as before but also set the fluid density to 0.5.

86rocco wrote:

jfholm wrote:Ed,
Thanks! very well explained
John

Except I made a stupid mistake

The scale length and vertical height need to be set to one half the calibration point. Or alternatively, set the scale length and vertical height to match the calibration point as before but also set the fluid density to 0.5.

Ed,
That really had me going because before I set the scale length and height to half it was showing me Delta P value at 52" and I was
After I reset it like you just said it works out the same as the calculation you gave me. But in reality if I just use the calculation you gave me is is less monkey motion and is actually faster to just use the calculation. This has been a great exercise though and I appreciate your time. I like to have backups because we all have our Murphy's Law moments

jfholm wrote: I like to have backups because we all have our Murphy's Law moments

I have a spare DM for my backup and never needed it yet . . . just sayin'

Brucepts wrote:

jfholm wrote: I like to have backups because we all have our Murphy's Law moments

I have a spare DM for my backup and never needed it yet . . . just sayin'

True Bruce, but I am one unlucky SOB I had the flood in my basement where my old bench was and the Black Box was soaked with water. I have not used it since so it may just be fine. But I wanted a back up way to do this when I get my new bench going. Money is a little tight right now. My property tax went up $1000 this year compared to last. That caused my house payment to go up $164.00 per month. On and On and On. So money is a little tight right now so I am being cheap.
John

jfholm wrote:Let's say my digital manometer breaks and I don't have a water manometer can I hook up my hand held digital manometer that reads inches of H2O to where the inclined manometer would connect and just take the reading in inches and use Ed's program to figure out the percentage from the inches of H2O reading. On the inclined compensation part of Ed's spreadsheet it shows a " in H2O reading for every percentage reading so I am assuming I could do that. Albeit not nearly as convenient and nice as using a digit manometer like Bruce's. But just in case of an emergency if you had to get a head done.

John

Not sure i am following this thread with good comprehension but there is no way i see you being able to accurately flow a head with a single component. "Delta P" at the end of the day you still have no scale to compare to (I/E DV Floating Depression) , but if you are looking for a cheep easy back up these $20 ebay manometers! two would cover your bases and eds sheet does everything just as it stands. plug your orifice in and read the DP at 28" and off you go.

My personal opinion is if the flowbench is Broken Fix it other wise go do some Honey DO's that way when it breaks again you have forgiveness on spending money to fix it. "It's Self Perpetuating"

Rick

PS. Did i mention the PTS DM has Great Customer Service