On our BOM we need to indicate filling pressure for tyres, so it can be used to generate work instructions and service manuals etc. For a given wheel and tyre combination the filling pressure might change depending on which product it is used on, so we want to treat it like oil, water or grease and add 1 usage of 'COMPRESSED AIR' to the EBOM and indicate quantity of 'COMPRESSED AIR' in psi or bar.
Is it possible to create a custom unit for pressure?
Yes you can add any unit of measure (UOM) you like to the system. In this scenario you need to go to the site or org level and go into "Type and Attribute Management".
There is a section for Manage Quantities of Measure.
Once you have the UOM, you can assign this as the default unit for the part you are creating.
I should have included, here is a link to the included units of measure in the system. This is what you would use for values in the newly created UOM.
Between my last post and this one should give you about what you need to define the units.