ARCHIVED REPORTS_REMOVAL ACTION COMPLETION REPORT

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memory, and then subtracts that background from all measured concentration values,until the zero is updated again by the user. Although zeroing can be performed as often as desired (e.g.,before every run),in practice it should not be necessary to do so more than once-a-month or even less frequently, except if average particulate concentrations should exceed about 0.5 mg/M-3. 6.5.1 Zeroing the model pDR-1000AN Zeroing of the model pDR-1000AN requires a particle-free environment such as a clean room,clean bench,duct or area directly downstream of a NEPA filter,or the pDR-1000AN Z-Pouch(standard accessory). In some cases,a very clean,well air conditioned office may offer a sufficiently low particle concentration environment (i.e.,<_5µg/m3) for zeroing,as determined by another monitor (e.g.,ME DataRAM). To zero the model pDR-1000AN by means of its Z-Pouch,proceed as follows: • Wipe the outside surfaces of the pDR-1000AN to remove as much dust from those surfaces as possible before placing the instrument inside the Z-Pouch. • In a reasonably clean environment,open the zipper of the Z-Pouch and place the pDR-1000AN inside it. Close the zipper shut. • Open the small nipple on the Z-Pouch,and insert the fitting of the hand pump/in-line filter unit into the nipple. • Start pumping the hand-pump until the Z-Pouch begins to bulge, and proceed with the steps in Section 8.1,pressing the keys of the instrument through the wall of the Z-Pouch.Then continue pumping. • After completing the zeroing (step 2. of Section 8.1)procedure,open the Z- Pouch zipper and remove the pDR-1000AN. Close the zipper and flatten the Z- Pouch while plugging its nipple,in order to prevent dust contamination of the interior of the Z-Pouch. • The pDR-1000AN is now zeroed and ready for a measurement run. 6.5.2 Zeroing the model pDR-1200 To provide the particle-free air required to zero the pDR-1200, either of two methods can be used: a) place the instrument on a clean-air bench or in a clean room,or b)connect to the cyclone inlet the green zeroing filter cartridge supplied with the pDR-1200. In either case,proceed as follows: • After implementing either of the two methods, above,run the attached pump for at least one minute (e.g.,at 4 liters/minute), and then proceed as described in Section 8.1 of this instruction manual,while continuing to run the pump (or leaving the unit in the clean air environment). 14