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Status Declined
Categories Asset Framework (AF)
Created by Guest
Created on Aug 19, 2022

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Add pH to the UOM database

pH is a common enough unit that it should be in the UOM database by default. It is also tricky for customers to add pH themselves and get the dimensions correct, so it is best that OSIsoft does this for us.
  • ADMIN RESPONSE
    Aug 19, 2022
    Thank you for your request but I'm going to decline this for now. I do not think we necessarily want to create a new UOM class for pH which would only have 1 UOM in the shipping product. We can revisit this at a later date if new information or use cases surface.
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  • Guest
    Reply
    |     Aug 19, 2022
    pH is typically unit less. I can see how having pH as a UOM would be beneficial for assigning an attribute value for contextual purposes, but I am having trouble seeing how one would use this UOM to, say, convert between different UOMs. Can you help me understand what you're trying to do?
  • Guest
    Reply
    |     Aug 19, 2022
    There's no such thing as a engineering unit called "pH".  As Steve mentioned, the pH is unit-less in the engineering community.  That is to say it is dimensionless.  I too wonder what your need is.  With PIPoints, I've seen others enter "pH" for the EU, but when they print out the tag name, value, and EU it would read like: pH: 7.5 pH, which was redundant.  Do you expect to have a UOMClass named pH with one and only one UOM?    See link https://chemistry.stackexchange.com/questions/10044/what-is-the-unit-of-ph
  • Guest
    Reply
    |     Aug 19, 2022
    I should have thought that through a bit better. Yes, pH is dimensionless. But I feel that it is not unitless (kind of). The measure is acidity, and we can measure acidity using pH or pOH, much like how angles are dimensionless, but we use the "unit" of radians or degrees. As I was writing this reply, I realized that a better counterargument to my suggestion is actually that the pH unit assumes that hydrogen ions are in the solution. Acids and bases do not necessarily made up of hydrogen or hydroxide, and they are not necessarily aqueous either. You can decline the suggestion if there's no reasonable acidity unit that could be put into the UOM database to represent p[cation] or p[anion].