A PROGRAMMABLE PARTICULATE SAMPLING SYSTEM

PERSONAL SAMPLER PUMPS ARE WORN BY INDUSTRIAL WORKERS TO DETERMINE THE CONCENTRATION OF PARTICULATES TO WHICH THE WORKER HAS BEEN EXPOSED DURING A WORK SHIFT. USUALLY A PARTICULATE COLLECTION DEVICE, SUCH AS A FILTER, IS WORN IN THE BREATHING ZONE OF THE WORKER AND CONNECTED TO A BELT-MOUNTED PUMP THROUGH A FLEXIBLE TUBE. THIS IS CUMBERSOME, AND OCCLUSION OF THE TUBE CAN CAUSE AN ERRONEOUS MEASUREMENT. ALTHOUGH CURRENT PUMPS MAINTAIN A CONSTANT AIR FLOW RATE DURING SAMPLING FOR ACCURATE DETERMINATION OF SAMPLED VOLUME, THEY MUST BE INITALLY SET WITH A FLOWMETER, AND FREQUENT CALIBRATIONS ARE REQUIRED. IN PHASE I A SYSTEM WILL BE INVESTIGATED IN WHICH THE SAMPLER PUMP INCLUDES A MINIATURE PNEUMATIC PUMPING UNIT THAT HAS A WEIGHT OF 4.4 OZ AND A VOLUME OF 8.8 CUBIC INCHES. THIS UNIT IS SUFFICIENTLY SMALL TO BE CLOSE COUPLED TO THE FILTER IN THE BREATHING ZONE, ELIMINATING PROBLEMS WITH FLEXIBLE FILTER TUBES. THE CONTROL SYSTEM USED PROVIDES AN ACCURATE SELECTED FLOW RATE BY INTERNAL CALIBRATION THAT IS STABLE OVER A LONG PERIOD. SETTING WITH AN EXTERNAL FLOWMETER OR CALIBRATOR IS UNNECESSARY. A SELF TEST FEATURE TO CHECK THE CALIBRATION IS ALSO PROVIDED. TO PREVENT ACCIDENTAL INTERFERENCE WITH OPERATION, OR TAMPERING WITH THE PUMP, SAMPLING VALVES ARE EXTERNALLY PROGRAMMED.