The Bigger Your U-Tube water,.....The More Inaccurite?????

[Flash]

So for every .826" rise with gauge oil = 1" or rise with water.....right?
sorry for the repetitiveness but i want to be sure i understand this first!

now assume the above it correct, with gauge oil, the one inch marks should be less then one inch.......right?

I just took a tape measure out to my 20 inch u-tube. From top to bottom, it is exactly 20"
At the bottom of the scale it says :Inch of water using water and mercury, using mercury:

So what i have is another water gauge, right?........this would explain the ration problem........

[86rocco]

So for every .826" rise with gauge oil = 1" or rise with water.....right?
sorry for the repetitiveness but i want to be sure i understand this first!

Because it's lighter, the oil moves further than water would under the same conditions so, 1" of oil movement is equivalent to 0.826" of water movement.

now assume the above it correct, with gauge oil, the one inch marks should be less then one inch.......right?

Depends on how you are measuring it, the easiest and most common way of doing it is to measure from the zero point along one leg of the manometer only i.e. measurement labeled "A", in this case, your marks are less than one inch, to be precise, they need to be 0.605" apart for 0.826 fluid.

However if you choose to measure the total fluid movement, measurement "B", your marks should be more than one inch, 1.121". For any U-tube manometer regardless what type of fluid is used B = 2 x A.

I just took a tape measure out to my 20 inch u-tube. From top to bottom, it is exactly 20"
At the bottom of the scale it says :Inch of water using water and mercury, using mercury:

So what i have is another water gauge, right?........this would explain the ration problem........

Correct, it's a water gauge and it most definitely explains your ratio problem.

[Flash]

so whats the math to figure this out.........
I'm wanting to change all my water gauges to MM oil(Marvel Mystery oil)

do you or some one have a program that would print out a sheet of paper that had the proper inch markings?

I thought Ray had one......but i can't find Ray's PM box to ask.....Hi ray

I would really like to change all the gauges to MM oil.......Winters are so frustration with water gauges.

[coulterracn]

Gordon, I did the math once when I did the drawings for the vertical manometers. I do not have the formula I used at that time.

Ray

[86rocco]

I don't have a program to print out a scale but the math is very simple. Referring back to my diagram, if you want to measure along scale B, your "inch" marks must be 1/(specific gravity of the fluid), and if you want to measure along scale A, the inch marks would one half that of scale B.

[1960FL]

Flash,

If you are trying to see the difference and reduce the chance of confusion you should get a good known scale say a 18" steel rule in 1/32 or so graduations. Then set you differential on your water gauge to exactly 10" or soothing like that to make the math easy. Then take the same rule and measure the difference on the Kohler monometer. Then do the math based on the specific gravity of the oil. I think yo will not be to far off you might find that you have some type of Scale issue as the specific gravity of Water does not change to much between roof temp 20° C and near freezing 0° C. See the chart.


http://www2.volstate.edu/CHEM/Density_of_Water.htm

There is something wrong with this setup oil, scale, water, scale????.

Oh, BTW you did't get that water from the mason jar in the bottom of my toolbox did you? cause that not water


Rick

[jfholm]

I thought I would give some input her. Marvel Mystery Oil has a specific gravity of .876. I have included the MSDS sheet here for both MMO and Dot 5 brake fluid. I have also looked at blue silicone brake fluid. It has a specific gravity of .958. If you would use that you would have less correction to worry about.

Now onto the math end of the question. Do you divide 1 by the SG of the fluid you are going to use i.e. MMO. or do you add the difference to 1? If you divide then you would have 1 divide by .876 = 1.142" So when using MMO your inch marks on your scale would be 1.142" apart not 1 inch.

Or do you subtract MMO SG of .876 from 1 which gives you the difference of .124" and add that to 1" which would put you inch marks on you scale at 1.124" apart. Which is the correct way to do this?

With Dot 5 silicone brake fluid your difference is .042" when subtracting the SG of Dot 5 from 1. If you do it the second way listed above then your 1" marks would be 1.042" apart. If the correct way is to divide 1 by .958 then you get your 1" marks being 1.044". The way I look at it I would probably use the DOT 5 silicone brake fluid and just make the 1" marks 1.043" apart and you would be splitting the difference and only be off .001" either way. I would hope that would be close enough

John

[Flash]

Hi john and thanks for the msds, was interesting.

There is two thing that i don't like with dot 5.
One is that it is a water exorbitant fluid, so the SG number may change over time.
2nt is it compatable with clear vinyl tube. Aka, will it cause the plastic to swell.

I have a MM oil gauge for my valosity probe that is over a year old now and seems to be holding up.
wish i still had that pdf file!!!

John have you experimented with this fluid(dot 5)

[1960FL]

There is two thing that i don't like with dot 5.
One is that it is a water exorbitant fluid, so the SG number may change over time.
2nt is it compatable with clear vinyl tube. Aka, will it cause the plastic to swell.

Flash,

I think you are mistaking DOT5 for DOT3 DOT5 is silicone and is not supposed to be Hydroscopic.

But what does that have to do with the issue you are having? have you figured out what is causing the error?

Rick

[Flash]

There is two thing that i don't like with dot 5.
One is that it is a water exorbitant fluid, so the SG number may change over time.
2nt is it compatable with clear vinyl tube. Aka, will it cause the plastic to swell.

Flash,

I think you are mistaking DOT5 for DOT3 DOT5 is silicone and is not supposed to be Hydroscopic.

But what does that have to do with the issue you are having? have you figured out what is causing the error?

Rick

I thought the Silicone brake fluid was real bad, for water exorpbsion .......no?

The error is have gauge oil in a water graduation U- Tube one inch is not one inch and grows with the hire the ## goes.
I have measured this gauge and they are exactly one Inch apart.......I don't know why it came with gauge oil but it did and is what sent me for a loop.

And by the way I'm not up set with Ray on this matter at all!!!!!
He sent me a gauge that he had never use and came with gauge oil, so he assumed it was calibrated for gauge oil......and so did I!
This was sent to me out of the goodness off his Hart!

I wanted a professional gauge to compare with my water gauge, to compare the variation see all winter long......................

At this point i don't care much about it. I need a new scale and new oil. whether it be MM oil, dot 5 brake fluid, or what ever.

I guess the question still remains, will it soften or swell vinyl/plastic hose?

And then, who has a printable scale for that SG ##