PTS Flowbench Forum

Hi,

I've been trying to find a suitable manometer fluid with specific gravity of 1.0 that would be an alternative to distilled water.
I've been using water for a little while now but it does go manky where we are fairly quickly and food dye tends to stain the tubing a little also. I have looked at the SG 1.0 oils offered by Dwyer and Meriam but they are expensive or won't export to the UK.
Has any one came up with an alternative to water that is not flammable and won't go off/stain the tubes?

Regards,

Stef

Steff,

There was a thread on the old forum on this and I had been looking into Silicon Brake Fluid as it is not hydroscopic and its SG is around .96 +.

Rick

Rick is correct,
the specific gravity for blue silicon brake fluid is .963. so close to tap water which is .998 or so.

John

Thanks for the replys. I looked at brake fluid as it was so close. Doing some calcs I was suprised to see that on the vertical manometer 25" of water would read nearly 26" with the brake fluid.
It's not too bad if your just doing before and after comparisons but I'd like to get some good accuracy also.

Stef,
Most beer is 1.01 sg of course you could wait until you drank it as urine is about the same SG
John

Stef,
You may want to consider distilled water and Fluorescein. Look at this link http://en.wikipedia.org/wiki/Fluorescein I have used it and like it a lot. Also if you want to hook up black lights you can also put on quite the show

John

Stef,

Your point is taken well but only if you are planning on doing everything in long hand arithmetic. I have searched High and Low for an economical fluid that could be used to replace water with the accuracy of water! There a lot of fluids with an SG of .99 to 1.01 but all you do not want to be around (Touch, smell etc). You could get into mixing multiple fluids like Dot 5 & something that is say 1.04 (Dot 3) in a 50/50 mixture to get an SG of 1.0 but then again your searching for something that will mix and still be clear and fluid and not gue in my brake line… The point behind Dot 5 was most of us use a computer to do the calculations and therefore it is easy to adjust for the SG difference. The SG has little to no effect on the incline as this is not a linear scale and unless you are using a % scale it is just a number you plug into a formula, then again if you are using a % scale you most likely made that so adjust it for the .963 SG. So for me if I know that my test depression is 28” then I set my mark at 29.0758  but remember if I am using water that could be from 28 to 28.125+ depending on where you got your water and how contaminated it is (Saponifier, dye, etc) ?

So my point is with our ability to do advanced calculations on the fly and since Depression is just an arbitrary point no one can decide on (10”, 16”, 25”, 28”, 34”, 40”,60” etc.) A known line on a stick is just fine, the rest is math as long as you consistently set your depression to that line on the stick, then again maybe we can get Bruce to have a vertical monometer scale made to a .963 SG fluid LOL!

IMHO and of course my working on the project gives me bias, I like Water as a Datum and find life a little simpler using the PTS Digital Monometer.

Thoughts?

Rick

After thought http://www.whittamprecision.co.uk/rfq.htm

I have a vertical scale that can be used with .876 Marvel Mystery Oil. It's a .pdf file with both 36-inch and 48-inch on the same sheet.

The .pdf file can be taken to a print shop and printed full size for a reasonable price.

Ray

stef-1 wrote:Thanks for the replys. I looked at brake fluid as it was so close. Doing some calcs I was suprised to see that on the vertical manometer 25" of water would read nearly 26" with the brake fluid.
It's not too bad if your just doing before and after comparisons but I'd like to get some good accuracy also.

I have not done the exact calculations, but..........

If you were to size the diameter of the well correctly with respect to the manometer tube bore diameter, you might be able to arrange things so that when the fluid rises 26 inches up the tube, the fluid in the well falls by one inch.

So in other words, the fluid in the manometer tube moves up 25 inches against a fixed scale. But the actual total fluid differential becomes 26 inches referenced to the one inch reduced level in the well.

So some sort of oil with an SG just below water, would be ideal for something like that.

Waddya guys think ?
Possible?
Or am I completely off my rocker ???

I'm pretty sure that's how the Dwyer well manometers are setup