On the face of some manometers, you may notice one or two scales. If there are two scales, the upper scale usually displays inches of wc, while the lower scale is in feet per minute (fpm). You will ...

David reinserted the two static probes, one on each side of the brand new filter, and measured a drop of 0.15 inches. He pointed out that although it was currently 0.15 inches, the pressure would rise ...