(Kyle R, Gerardo M)
Last night while doing some work around the HAM5 I noticed the door cover for HAM5 being "sucked in" (see photo), that occurred every time someone removed the door cover to any other HAM chamber (4,3 or 2), it turns out that the new cleanroom creates great positive pressure causing the door cover for HAM5 to appear as being "sucked in". So I ran a little test, while one of the other door covers was off and HAM5/HAM6 door covers on, I pushed some of the cleanroom curtains open, and that relieved some of the positive pressure created by the cleanroom HEPA fans, that allowed the purge air to "balloon" the door covers on HAM5, and as soon as I closed the curtains the door covers went back to getting pushed in towards the chamber.
Today Kyle and I used a long ladder to get access to some of the HEPA fans, there are 20 of them on that cleanroom, we dialed down 7 of them and there is a noticeable difference already, we plan to dial down some more tomorrow as work on that chamber allows it.
You guys should check that the gap at the foot of the curtains is correct - refer to PSI drawings - this is intended to exhaust the air without building pressure in the cleanroom. It may be better to leave the flows at nominal and relieve pressure that way. By dialing back the hepa units you are decreasing the volume flow rate of clean air which may not be the right thing to do.
This cleanroom is the "gerbig" style with 20 HEPA filters and 1 ft clearance at bottom (non adjustable legs). We checked the particle count after dialing down flow; cleanroom is still running well below Class 100.
Thanks!