Manometer Fluid?

[98-1074649673]

I setup my Dwyer inclined manometer on my flowbench this past week and I'm to cheap to buy red manometer fluid, so I'm using mineral oil instead (referenced as the same specific gravity in an old manometer book I have). Now my question is what do I use as dye? Water based food coloring will not work. I've heard/read the ink in a ball point pen or magicmarker will work? Anyone try this? I'll have to setup a test of this idea maybe? Any other ideas? I dont want to stain the inside of my meter (I do have some old meters that are not that great to practice on).

Please don't tell me to go buy fluid (or I'll delete your post) . . . its all about the DIY aspect

[84-1074663779]

As to dye, the only thing I can think of that might work in oil would be anodyne/analine dye as used to colour petrol and I believe to give the colours to anodised aluminium. Where you get it, I would not have a clue. I am still not sure which term anodyne or analine is the corret one, both seem to be in common use for the same stuff.

Some auto transmission fluid, or brake fluid comes in pretty vivid colours, I have no idea what the specific gravity might be. It would not be difficult to set up two manometer tubes side by side and compare fluid X with water and measure an exact difference.

The human eyeball is most sensitive to green, so that would be my colour of first choice. Oscilloscopes and night vision equipment have green screens for a reason. It probably comes from when our ancestors were living in the trees. Green is right in the middle of the visible spectrum, right at the very peak.

Hehe, Bruce, if you want red, have you tried blood ?

[Mouse]

Maybe paint tinting. You can buy tubes of it at most paint and hardware stores. It should disolve in oil. But I don't know if it would change the SG or stain your tubing.