Hanna-instruments HI 8614 Manuel d'utilisateur télécharger pdf (Page 8)

1514

SLOPE ADJUSTMENT

OFFSET ADJUSTMENT

• If the reading lies outside

this range, adjust the slope

adjustment trimmer on the

transmitter for a reading just

within this range.

The unit is now calibrated.

A complete calibration of the transmitter mod-

ule is advised periodically.

This calibration procedure requires the HI 8427

or the HI 931001 pH and ORP simulator to

simulate the ORP electrode.

HI 8427 or HI 931001 produce a known signal

into the system so that the faults of the

system can be isolated.

• Connect the ORP transmitter to the simu-

lator.

• Set the simulator to 0 mV and adjust the

offset trimmer to read 12 mA on the am-

meter or 0 mV on the HI 8615L display (HI

8615L only).

SLOPE ADJUSTMENT

OFFSET ADJUSTMENT

mA

ORP CALIBRATION (HI8615 & HI8615L)

Initial preparation

Disconnect the +ve supply cable from the

"+VE LOOP" terminal and connect a 20 mA

f.s. ammeter between the +ve cable and the

"+VE LOOP" terminal. With HI 8615L the

instrument display can be used during cali-

bration without the need to connect the am-

meter. In this case the values are directly

expressed in mV units.

Pour a small quantity of HI7020

ORP solution into a beaker.

Procedure

• Connect the shorting BNC

connector to the ORP trans-

mitter.

• Adjust the OFFSET AD-

JUSTMENT trimmer on the module for a

display of 12 mA on the ammeter or 0 mV

on the instrument display (HI 8615L only).

This sets the zero point for the transmit-

ter.

• Connect the ORP electrode to the transmit-

ter and immerse the tip of the electrode

into a beaker of HI7020 ORP calibration

solution, and check that the ammeter read-

ing lies between 13.6 and 14.2 mA or the

instrument reading is between 200 and 275

mV at 25°C (HI 8615L).

HI 7020

mA

SLOPE ADJUSTMENT

OFFSET ADJUSTMENT

mA

HI 7020

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