HQ Series Portable Meters

LDO Operation and Methods

8.4.5 Selecting a LDO Calibration Setting

Important Note: Factory calibration is the default setting. Factory calibration coefficients are stored in the iButton.

Water-saturated air is recommended for calibration of the HQ series meters, however a water sample with a known dissolved oxygen concentration can also be used. The dissolved oxygen concentration must be determined by Winkler titration, or by calculation of a saturated-air water sample using existing pressure, temperature, and salinity conditions.

Note: Factory calibration is the default setting. For information about manual calibration, see

section 8.2 on page 71

.

Each lot of LDO sensor caps is factory calibrated. Performance will vary slightly as a function of usage history. For best performance, a one-time calibration initialization can be performed when a new sensor is installed. Additional calibrations can be performed at the operator's discretion but are not required. Use the Calibration

Standard option to use a water sample as the calibration standard:

1. Use the

UP

and

DOWN

keys to highlight Calibration Standard in the Modify Current Method menu. Press the

GREEN/RIGHT

key under Select.

2. Use the

UP

and

DOWN

keys to select mg/L. Press the

GREEN/RIGHT

key under OK.

To use water-saturated air as the calibration standard:

1. Use the

UP

and

DOWN

keys to select 100%. Press the

GREEN/RIGHT

key under OK.

8.4.6 Selecting a LDO Method

Select which method to use when additional methods have been entered in the LDO Options menu.

1. Use the

UP

and

DOWN

keys to highlight Current Method.

Press the

GREEN/RIGHT

key under Select.

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