Hach BODTrak II, Руководство пользователя

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13. Push and hold
ON to start a test. A
graph will show.
Note: To cancel a test,
push and hold OFF.
There is a built-in 1
hour instrument/sample
equilibration period
before data collection.
The display shows
"DELAY" during this
period.
14. Do steps 10
through 13 again to
set the test range
and start each of the
six channels. It is not
necessary to operate
all six channels if
less than six
samples are
available.
Section 8 Determination of results
After the end of the selected test period (5, 7 or 10 days), the display
shows "END". The results are given based on the selected procedure:
Simplified or Hach Standard Method.
8.1 Simplified sample results
The simplified procedure results are shown on the BODTrak II display.
Push the applicable channel selection key to show the results.
Note: If the sample was pre-diluted, apply a dilution factor to the instrument
reading. Refer to
Sample dilution on page 15.
8.2 Hach Standard Method results
1. Push the channel selection key for the Hach Standard Method
sample bottles, and the seed blank bottle and GGA bottle when
applicable. The results are shown.
Note: Treat the seed blank the same as all other samples. If the sample was
pre-diluted, apply a dilution factor to the instrument reading (
Sample dilution
on page 15).
2. Find the dilution factor based on the selected range ( Table 5
on page 11). For example, if the sample range selected is 0 to
350 mg/L BOD, the dilution factor is 1.45.
3. Calculate the corrected results:
BOD mg/L = BOD mg/L (instrument reading) x dilution factor
Example:
• Instrument Reading = 200 mg/L
• BOD dilution factor = 1.45
200 mg/L x 1.45 = 290 mg/L BOD (corrected result)
4. When the samples are seeded (not GGA), calculate the results with
the equation that follows and the corrected results:
BOD (mg/L) = A – [B x (SA÷SB)]
Where:
• A = corrected BOD of the seeded sample
• B = corrected BOD of the seed blank
• SA = volume of seed in seeded sample
• SB = volume of sample in seeded sample
Example:
• A = 290 mg/L BOD
• B = 120 mg/L BOD
• SA = 20 mL
• SB = 110 mL
BOD (mg/L) = 290 mg/L - [120 mg/L x (20 mL÷110 mL)]
BOD mg/L = 268 mg/L
5. For GGA, calculate the results of the GGA with the equation that
follows and the corrected BOD of the seed blank:
BOD (mg/L) = C – [B x (SA÷SC)]
Where:
• C = instrument reading on seeded GGA
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