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Section No. 2.2.4 <br />Revision No. 0 <br />Date May 1, 1977 ~ '~.j <br />Page 8 of 17 <br />2. Filter resistance and associated flow rate readings may <br />change with time because of weather changes or changes in the <br />condition of the sample deposited on the filter. If a clock <br />switch is used to start and stop the sampler at preset times, <br />flow rate measurements should be made within 30 minutes of the <br />actual start and stop times to minimize discrepancies in <br />in flow rate readings. If it is not practical to make the <br />final flow reading within 30 minutes of stop time, the sampler <br />should be turned ON and warmed up for 2 to 3 minutes prior to <br />recording the final flow measurement. <br />4.2.2 Flow Rate Measurements on Flow Recorder Equipped Sampler - <br />The following operational procedure is provided for use with <br />Hi Vol sampler equipped with flow recorder. <br />1. Record on the backside.of the new chart the filter <br />number, station and sampler numbers, start time and date of <br /> <br />start time. ~ ; <br />2. Remove any moisture from inside the recorder case <br />by wiping with clean cloth. Carefully insert the new chart <br />into the recorder, being careful not to bend the pen arm be- <br />yond its limits of travel. An easy way to 3o this is to push <br />in on the extreme top of the pen arm with the right hand to <br />raise the pen head while inserting the chart with the left <br />hand. A properly installed chart is shown in Figure 4.6. <br />Be careful not to damage or weaken the center tab on the chart <br />and make certain that the tab is centered on the slotted drive <br />so that the chart will rotate the full 360 degrees in 24 hcurs <br />with no binding or slippage. <br />3. Check to see that the pen head rests on zero (i.e., <br />the smallest diameter circle on the chart). If it does not, <br />tap the recorder lightly to make certain the pen arm is free; <br />if it still does not read zero, adjust to zero with the adjust- <br />ment screw (follow manufacturer's direction for specific • <br />recorder). <br />