Lubrication properties of deionised and demineralised water
Lubrication properties of deionised and demineralised water
(OP)
I know from practical experience of mono pump rotors that DI and DM water is a poor lubricant, when compared with regular water. It also provides poor lubrication to mechanical seal faces, causing less than expected seal life.
I have searched all over the place for some science to back up these observations, however I cannot find an explanation of why this might be. Does anybody have any ideas? or point me in the direction of where I might find the information?
I have searched all over the place for some science to back up these observations, however I cannot find an explanation of why this might be. Does anybody have any ideas? or point me in the direction of where I might find the information?





RE: Lubrication properties of deionised and demineralised water
One thing to consider is viscosity. Water devoid of minerals and organic matter I suspect to be less viscous than water rich with either or even both. In the absence of available information it would be well worth testing.
Another thing might be the effect of DI & DM water as a corrosive agent abrading the surface.
RE: Lubrication properties of deionised and demineralised water
RE: Lubrication properties of deionised and demineralised water
What I meant to infer in the last sentence of my earlier post 4 Oct 05 4:21 was as DM/DI water corrodes/errodes the shaft it might cause irregular jagged edges to appear on the shaft surface and grind against the contacting seal. Water flushes the debris away and thus forms a continuous cycle of corrosion/erosion to shaft, leading to abrasive wear against seal and shaft.
Just curious, but could you find out what resin type was used to bind the faster wearing carbon seal material?
I suspect antimony plays a beneficial mechanical rather than chemical role in prolonging seal life.
RE: Lubrication properties of deionised and demineralised water
Another thought on the problem on the seal faces is that the surface tension on DI water will be lower than regular water. This will provide a less efficient fluid flim.
The investigation continues.......
RE: Lubrication properties of deionised and demineralised water
RE: Lubrication properties of deionised and demineralised water
It would be worth immersing a few new seals in DM & DI water with no metal contact to see whether they deteriate as a direct result of only water rather than contact with water and metal.