PTS Flowbench Forum

Tony wrote:This is not correct !

Ten inches rise could be measured on a ten inch scale vertical manometer.
Only disadvantage of doing that is the graduations would be extremely close together and difficult to read.

Or the scale could be a mile long and still have a ten inch rise at the far end.
The angle of slope is irrelevant.
If you have ten inches of pressure it will lift the water ten inches, no matter how long the manometer tube is.

You make your scale any length you want, mark off the square law divisions, and you are set to go.
You then raise one end to give you the required amount of rise.

Yep..it could be 47 miles long. Once you change the angle so is the scale. Do the math.

Tony,

As I see it, the angle of the slope is irrelevant. UNTIL you mark the scale. At that point, it's carved in stone [or aluminum as the case may be]. Why do you think they bother to put a level on a Superflow Manometer?

If angle doesn't matter" then one could rotate the angle right around to 89 degrees and the scale would be correct. Not going to happen.

Larry, obviously you need a level, because if the bench is down an inch on one side, your ten inch rise might end up being be nine inches or eleven inches.
With a vertical manometer it makes little difference if its a bit off vertical.
The lower the rise, the more critical levelling becomes.

Yes you can rotate the scale around to 90 degrees (vertical) and it WILL be correct.
If your scale is 30 inches long, and 100% flow will now be at 30 inches of water rise.

If you lower the angle to thirty degrees, then 100% flow on the scale will equal exactly 15 inches rise.
That will be true because the sine of 30 degrees is exactly 0.5

Not only will the zero and 100% points be perfectly correct, all the square law divisions in between will be correct too for the new 15 inch rise.

I think Erland Cox usually run a 10" or 12" rise on his inclined, and if need be he just pivots the inclined - being fastened at the same point as 0% flow - to 18", and run a calibration run to position it accurately and then flowtest whatever big-flowing part he had to get numbers from... Atleast that is what he did before.

larrycavan wrote:Why do you think they bother to put a level on a Superflow Manometer?

If angle doesn't matter" then one could rotate the angle right around to 89 degrees and the scale would be correct. Not going to happen.

They buy a standard Dwyer model 246 off the shelf water gauge which comes with a level installed, all Superflow does is change out the inch scale to a percent scale. I actually have the same gauge setup in my shop with percent scale for testing. If you use the standard Dwyer water gauge with an inch scale you would want it to read correctly in an HVAC environment so they come with a level installed to make sure it is reading inches of water correctly.

SF benches have no way of calibrating the fixed scale water manometer to a set of calibration plates other than a correction factor, The quality of the SF internal orifice holes do not match from one machine to another so each range is different. You could probably not find two SF's that have matching ranges as hole diameters are at best +/- .002"(?) between benches (going from my memory and not my notes). You will find no two SF600's that have the same range plaque. If one were to be able to change the angle of the inclined water gauge you would be able to match any SF600 to any other SF600 using a set of calibration plates by simply matching the percent scale to the internal diameter range. But, one can only assume the internal orifice diameter for math purposes (unless you actually measure them) as SF does not supply that info with the flowbench just a range plaque on the side of the flowbench.

I've worked with more than a few SF600 customers swapping over to digital now to see this trend on these machines. I have gotten a pretty good education of the SF600 dealing with this issue. As the serial numbers have gotten higher the quality of the internal orifice holes has come down and required correction factor has gone up.