Assuming that you are using the Size parameter, this cannot be done with 1 filter. I tried to find a solution to this recently. When you select Size as a rule, you get a list of all of the pipe fitting sizes (i.e. 3/4-1/2" & 3/4"-3/4").
Because the size parameter differs in value between these two, one filter will not work. Additionally, Even by changing the pipe size units to decimal units, you still can't capture the pipe fittings with the same filter. You would have to have 1 filter for each pipe fitting size.
If you are in 2019 or newer, the filter rules have been upgraded to allow the OR option. You also can select which rule applies to which category inside the same filter, and can make this happen. This reply probably isn't relevant now, but hopefully it helps someone out there.