Extech Instruments VPC300 - Page 14

(How to Use the Extech VPC300)
25. Also, be sure to zero out the particle count sensor from time to time (see step 29 for more
discussion). First, unscrew (“righty tight-y, lefty loose-y”) and remove the isokinetic probe.
26. Then attach Zero Count Filter in place of isokinetic probe.