Faulkner (1995) describes the results of a study using a particle counter in a cleanroom.
Data acquisition using a new particle counter is complete. A new control scheme was tried that proportionally increased the fan speeds based upon the magnitude of measured particle concentrations. The previous control scheme always increas[ed] the fan speeds by 10% whenever the particle concentration was above a set limit. The new control routine increased fan speeds by more than 10% in proportion to the amount that the particle concentration was beyond the limit. Thus if the particle concentration was just beyond the limit, then the fan speeds would be increased by 10%. Whereas if the particle concentration was far above the limit, then the fan speeds would be increased by 30 to 40%.
The energy savings with the new control routine are ... 60% savings ... This energy savings of 60% may be the maximum possible for our cleanroom, particle counter, data acquisition and control system. With the control schemes that we have tried, the particle concentration in the cleanroom has gone outside Class 100 criteria occasionally. Usually the particle concentration is outside Class 100 status for one minute or less and will occur 3-7 times per day. We are not sure if this will be viewed as a problem for industry cleanroom users. We have had no complaints from users.