Hello everyone, we are working on a laboratory and we have very restrictive filtering in some spaces there are equipments that have MERV 7 + MERV 13 + MERV16 filtering sections.
In the ASHRAE preassure adjustment calculations we have that for MERV 7 we have a adjusment of 0.5 in.w.c.
MERV 13 is 0.9 in.w.c.
MERV 16 is calculated 2x the clean filter which is 1.8 x 2=3.6.

¿How do we calculate the adjustment ?
0.5+0.9+3.6=5 or (0.5+0.9+1.8)x2=6.4

Thanks for your help.