new to the forums

[rb209]

Hi, I am new to these forums. I'm also new to this whole flow bench building. Ive been reading and trying to learn as much as I can. I still dont fully understand how a flowbench works or how to use one lol so I would like build a simple one to learn on first. I was thinking about getting the PTS plans but had a couple questions. The plans say they are digital based but I would like start with water manometers. Is the info to design water gages included in the plans yet? One more question On the parts page there are deck plates for sale. I was just wondering what these are for? Thanks

[Tony]

Hello rb209, welcome to the Forum.

A set of flow bench plans would be the very best way to get started. Keep reading, all the information you need is right here, it just takes a fair while to get through it all !! They are a very friendly and helpful bunch of guys here.

I am using water manometers on my own bench, nothing at all wrong with that, and it is a very simple way to get started. I built my bench a very long time ago, and at the time there was no affordable alternative to water manometers, so that is what I still have.

But honestly, at the price the PTS digital system is being offered, it is hardly worth the trouble to scrounge all the basic materials to build some good looking water manometers. You can, but why even bother ?
If you do decide to use water manometers, there is plenty of information here on the Forum on how to go about it.

The flow measurement orifice plate is located deep inside the bench, and it may need to be changed to suit greatly different flow ranges. The deck plates provide an air tight "door" that you can open up for access to the measurement orifice.

These deck plates are normally fitted to the decks of yachts to provide water tight access to storage lockers located right beneath the deck. They provide a very simple and effective air tight access to our measurement orifice. A low cost and very effective solution.

[rb209]

Thanks for Reply

I've been doing alot of reading and it is all starting to make sense. I will probably start with water manometers and then upgrade to the digital version once I learn how to use the flowbench.
Another question though. When you said to change the orifice plate for different flow ranges. Do you mean you use different orifice plates for example 100 to 200cfm, 200 to 300cfm etc. Would this be at the same test pressure? This is where I start getting confused Lol

[coulterracn]

Hello rb209,

The orifice plates are sized for a specific CFM.

Example: If you are flowing a cylinder head port that will flow between 260-280, a 300 CFM orifice plate would be used.

You then set your test pressure (maintain same test pressure throughout test) at each .050" or .100" of valve opening on the vertical manometer. The precentage reading on your incline monameter is used to calculate the CFM's flowing thru the port.

The precent of flow scale for the incline manometer can be calculated using the spreadsheet found in the forum. Fellow members here will help by giving you sound advice.

Ray

[coulterracn]

Calculating CFM from orifice plate and precentage scale on incline manometer:
Example: the precentage on the incline scale is 80%, 300 X .80 = 240CFM

After you do this a few times it get's easier and is easier to understand

Ray

[bruce]

I do not plan to add support to the plans for water gauges. Each set of water gauges would be unique to one's material uses in their gauge build. Read all the posts you can here about water gauges, there are some pretty indepth discussion of various designs that have been built and can be easily copied.

Once you have an understanding of the principals feel free to ask questions along the way. It seems to me to be easier to address a particular build as it is being built so, new forum posts are encouraged to address a specific build.

The forum members who have built water gauges are more than willing to help anyone along.



Edited By bruce on 1247919800

[rb209]

Ok I think i am starting to understand it a little better. So for example, If you need to flow more than you move up to a bigger orifice plate and use the inclined manometer reading to calculate the flow.
That is one thing that I didnt know was the inclined manometer used a percentage scale. Now if the orifice is sized for a specific cfm. Is it measured at the same test pressure you use on the flow bench. Hopefully this makes sense. :laugh:

[coulterracn]

The test pressure reading is taken off the vertical manometer which is marked in inches of water. The industry standard for test pressure is 28 inches of water rise. Some flowbenches flow at lower test pressure and then can be converted to 28 inches.

The test pressure for flowtest should be the same for each valve opening reading.

Ray

[49-1183904562]

RB209,

The incline scale does not have to be percentage based tht is done for ease of use. As ray said if you had a 100cfm plate inthe machine you could easly look a percentage scale and extrapolate your numbers I/E 80% would be 80cfm.

But for learning you can go to the forum and download a spreadsheet that will help you learn the math thus you might enter into your spreadsheet the inch measurment on the incline an it will give you the flow. I think slracer (Doug) posted one a while back (there are serveral from others too).

Rick

[slracer]

RB209 (and Rick), I modified the sheet that Ed (rocco86) made for use with my pitot bench (aka the Dark Side). It is in metric units so I added a "converter" for those of using "Imperial" units. But Rick is right, there is plenty of info here if you need a headache! :p A really good thread you should read is here:

When you read and understand this, you are really on your way. It starts with Ed's sheet for orifice benches and includes a lot of manometer data/calcs! Welcome to the Forum!

Doug

[rb209]

Ok after hours of reading and research I have a couple more questions. I was playing around with the spreadsheet that was posted and I understand most of the math. Like the square law relationship with pressure and flow. But what I was wondering is about the rise on an inclined manometer. Do you set your rise to whatever pressure drop the orifice is rated for?

Now if I wanted to find the percentage would I use this: (distance along scale/ scale length) than square root of that number. Now multiply this by orifice rating gives actual flow. Does all of this sound right? lol I never knew there was this much involved in flow benches.

Thanks for all the replies so far.

[coulterracn]

[bruce]

You want your differential pressure (Dp) across the orifice to be the same as your manometer rise. You might have to tweak this rise to get it to match exactly based on a calibration plate ie your plate could be a 6" plate but on your manometer you might have a slightly higher or lower rise than 6". The spreadsheet will get you close but in the end you will have to calibrate the bench using a known orifice plate.

The lower your rise the larger your orifice hole will be for a given CFM. What is the perfect rise? I doubt anyone could offer that advice and be 100% percent sure. I have found a higher Dp seems to show less "bounce" in readings.

[jfholm]

To add to Bruce's comment:

I have a 36" lnog inclined with a 12" rise using water. I have input my tubing id and resevoir id into the spreadsheet and it gives me a Delta p of 13.10" H2O. So that is what you calculate your orifice to that is inside your bench. So you would calculate what your orifice diameter's flow is at i.e. on mine, 13.10 "H2O for you 100% mark.

Now as Ray has pointed out if you change what fluid you are using it will also raise or lower your Delta P and that can also be calculated with the spreadsheet by inputting the specific gravity of your fluid.

John

[rb209]