PTS Flowbench Forum

OK, thanks Tony.

Doesn't sound too bad for a 'cheap @ss' start with my own heads. Would have to make couple of Excel charts for different orifice sizes, where I put the actual manual reading reading and the chart calculates the flow#...

Well, it took my lovely wife less then 2 minutes to come up with a chart....

Been playing more...it's getting better:

Yup, you are certainly off to a running start with all this.

Two of those e-bay digital manometers and a five dollar pocket calculator, (or a spread sheet program) is all you need to get going once you have one of Bruce's orifice plates.

One other point to ponder.

A ratiometric flow bench flows the exact same volume of air through both the test object and the measurement orifice in series.

The flow capability for the reference orifice is known, the flow figure for the test object is what we wish to discover.
What is important is the pressure ratio between the two. So if your test pressure measures maybe 27.8 inches instead of an ideal 28.000000 inches, use the 27.8 inch figure to calculate the pressure ratio.
The calculated flow reading will then still be correct.
By all means try to maintain 28 inches test pressure as closely as p[ossible, but don't sweat trying to get it absolutely exact at every valve lift increment.

Once you have all the basic concepts in mind, it is possible to build a home flow bench of as good or very likely better accuracy than a very high dollar commercial flow bench.

Thanks Tony, your a good help!

I think that my electricity connection, might be the limiting factor. Since I'm not connected to industrial power supply (400V), I'll have to use 220/240V network - 3.5kW, which will limit me to 4 motors only...

I've found some specifics of a 1200W Domel motor, which should provide enough CFM - aiming for 300 with 4 motors.


There's also a 1400W version, but I can't find the flow data anywhere. Logical thinking would say it should give more CFM.....

This one:

As you are power limited, the numbers to look for are CFM per amp at around 44 inches total back pressure. (28" + 16")
Some rough and ready interpolation is usually required, but it is a good basis for direct comparison.

Single stage motors will be more efficient at our pressure levels than two stage vacuum motors.
That should narrow down the search.
Motor size seems to have no direct bearing on the efficiency, but efficiency is what you need most where mains amps are limited.

Work out how many motors you can support, and add one more, and then fit an amp meter to the bench.

Had already read/figured out about CFMs @ 44", that's the number I'm focussing at when checking flow #'s.

What do you want to achive by adding one extra motor and an Ampere gauge?

Old School wrote:What do you want to achive by adding one extra motor and an Ampere gauge?

Always nice to have a "little more" if you need it

The AMP guage so you can see how much $$$'s you are spending on electric

It's not required but you can find some pretty resonably priced ones on ebay so it's a nice thing to add

Brucepts wrote:

Old School wrote: The AMP guage so you can see how much $$$'s you are spending on electric

It's not required but you can find some pretty resonably priced ones on ebay so it's a nice thing to add

Here is a link to the amp gauge/volt meter I just bought. Great price and decent delivery time. I am going to use it to see how close I am to blowing my breakers

http://www.ebay.com/itm/170878884488?ss ... 1439.l2649

John