When you set an equipment as "consumable", you are implying that:

1. You are not interested in telling one item from another
2. You are only interested in knowing you have at least a set amount in stock (this amount can be configured).

This is probably how you would set some filters that cannot be serviced and have to be replaced by a new one after a certain time. You do not care where each unit is, you care only that you have enough in stock for the next change.

So comma CMMS will never tag a consumable as "in service". Consumables are always in stock (although you can have a stock quantity of zero).