I have not been on for sometime.  I do not know if this little issue ever has been raised. 

We have a debate going on in our treatment plant about the numbering of tanks.  Do you look at the flow coming toward you or going out to number the left tank(aeration tank for example) as 1 and the right tnak as 2 or the other way around ?  Does the U.S. EPA have any say about this ?

The way I am comfortable with is take into consideration which direction is north when the original drawings were done(facing north       

left to right for example left #1, right #2 etc.) and also use the blue prints and drawings to decide as the Electrical, Mechanical,Structural  drawings should show in some cases the equipment #s so there is no confusion when locking out equipment. Years ago there was a close call when the main disconnect was isolated for the wrong piece of equipment because the equipment was not labeled the same as the electrical drawings, an important lesson to be learned here follow the drawings.

regards, D.Mak