Spyker,
I have not been able to find a way to have the query from one property be used as a filter in another property.
The only way I can think of doing this is to build a series of instrument classes under instrument for each type of component - Pressure, Flow etc. Then in your database create a field for DEVICE_TYPE_CODE_FUNCTION with the letters of P, F etc. This way you can use the select statement to have the Device Type Code only return the list as it pertains to the Device Type Code Function.
SELECT DEVICE TYPE CODE from Instrumentation_ISA51 where Device Type Code FUnction = 'P'
If you feel that a custom attribute that can use another porperty as a filter would be beneficial to have then please log a service ticket as an Enhancement Request vis the Bentley Support website.
Tony DeRosa
Bentley Plant