Abstract: A flow rate controlling system includes: a flow rate balance determining portion that determines a supply flow rate, regulated by a supply air valve, and a common exhaust flow rate, regulated by a common exhaust air valve, so that a difference between the supply flow rate and an exhaust flow rate, regulated by the common exhaust air valve, matches a set point; a valve monitoring portion that monitors the supply air valve, the common exhaust air valve, and a local exhaust air valve; and a flow rate changing portion that issues a flow rate changing instruction to the flow rate balance determining portion. When there is a fault in the supply air valve and/or the common exhaust air valve, the flow rate balance determining portion, upon receipt of the flow rate changing instruction from the flow rate changing portion, changes neither the supply nor common exhaust flow rate.

Abstract: A flow rate controlling system includes: a flow rate balance determining portion that determines a supply flow rate, regulated by a supply air valve, and a common exhaust flow rate, regulated by a common exhaust air valve, so that a difference between the supply flow rate and an exhaust flow rate, regulated by the common exhaust air valve, matches a set point; a valve monitoring portion that monitors the supply air valve, the common exhaust air valve, and a local exhaust air valve; and a flow rate changing portion that issues a flow rate changing instruction to the flow rate balance determining portion. When there is a fault in the supply air valve and/or the common exhaust air valve, the flow rate balance determining portion, upon receipt of the flow rate changing instruction from the flow rate changing portion, changes neither the supply nor common exhaust flow rate.

Abstract: An aluminum foil for electrolytic capacitors in which the sub-surface layer having a depth range from 0.1 to 0.2 .mu.m below the surface contains at least one element selected from the group consisting of Pb, Bi, and In at a total average concentration ranging from 0.001 to 0.1 wt %, and in which the inner part below the sub-surface layer contains less than 0.0001 wt % average concentration for each of Pb, Bi, and In, and in which the average aluminum purity throughout all layers from the surface to the inner part is not less than 99.90 wt %. This aluminum foil has adequate development of tunnel type etch pits and possesses superior electric characteristics and strength.