Emerson 54e pH/ORP Autocal buffer, Buffer 1 -- Wait, Automatic TWO-POINT Calibration

MODEL 54e pH/ORP	SECTION 4.0
	CALIBRATION

4.2 AUTOMATIC TWO-POINT CALIBRATION

The two-point calibration is performed when the controller is initially installed and whenever elements of the sensor assembly or controller are replaced. The two-point calibration re-establishes the slope of the elec- trode. This is necessary because the slope (mV/pH change) decreases as the glass pH electrode ages.

7.00pH

Hold Mode: Off

Exit Cont Edit

Buffer calibration Standardize pH Adjust temperature

ExitEnter

Buffer calibration uses measurements of two solutions to calculate the slope (efficiency) and the zero offset of the pH sensor.

Obtain two pH buffer solutions with different pH values. They should be at least 2 pH units apart. Unopened buffers have a shelf life of about a year and should generally not be reused because of possible contamina- tion.

Before taking readings, clean and rinse the sensor (if necessary). Shake the sensor down to remove air bubbles from the glass electrode tip. Place the sensor into the first buffer solution. Verify and adjust the temperature (Section 4.1), if necessary.

The controller is set at the factory for automatic calibration. If this feature has been disabled (Section 5.9), see Section 4.3 for manual calibration.

Auto calibration includes automatic buffer recognition (factory set buffers are 4.01, 7.00, and 10.01 pH) and a stabilization check. The stabilization feature eliminates errors caused by changes in temperature and response time of the glass electrode. To change these settings, refer to Section 5.9.

1.From the main display, press any key to obtain the main menu. With the cursor on "Calibrate", press Enter (F4). With the cursor on "Buffer calibration", press Enter (F4) again.

NOTE

The hold mode screen (top left) will appear if the hold mode was enabled in Section 5.6. Activate hold mode by pressing Edit (F4), using the arrow key to change Off to On, and then pressing Save(F4). The hold mode holds the outputs and relays in a fixed state to avoid process upsets to a control system. To leave the hold mode in it's current state, press Cont (F3).

4.02pH

Autocal buffer 1

2.With the sensor in the first buffer, press Cont (F3). To cancel the cal- ibration, press Abort (F1).)

The word "Wait" flashes until the sensor is stabilized.

Abort Cont

4.02pH

Buffer 1 -- “Wait”

The controller is waiting for the pH reading to stabilize within the parameters established in Section 5.9. If the controller appears to be locked at this stage, the reading is not stable enough. Increase the stabilize pH and/or decrease the stabilize time and retry the calibra- tion.

Press Abort (F1) to cancel the calibration if it appears to be taking too long.

Abort Cont

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