Emerson PN 51-FCL-1056 instruction manual Simulating Inputs pH, Simulating pH input

MODEL FCL-1056

9.9 SIMULATING INPUTS — pH

9.9.1 General

This section describes how to simulate a pH input into the analyzer. To simulate a pH measurement, connect a standard millivolt source to the analyzer. If the analyzer is working properly, it will accurately measure the input voltage and convert it to pH.

9.9.2 Simulating pH input.

1.Set automatic temperature correction to manual and set manual temperature to 25°C. Turn off solu- tion temperature correction. See Section 5.6

2.Disconnect the sensor and connect a jumper wire between the IN REFERENCE and IN pH terminals.

3.Press DIAG and choose sensor 2 (pH). The input voltage should be 0 mV and the pH should be 7.00. Because calibration data stored in the analyzer may be offsetting the input voltage, the displayed pH may not be exactly 7.00.

4.If a standard millivolt source is available, discon- nect the jumper wire between IN REFERENCE and IN pH and connect the voltage source as shown in Figure 9-4. Be sure to jumper the IN REFERENCE and GND SOL terminals.

5.Calibrate the analyzer using the procedure in Section 6.4.4. Use 0.0 mV for Buffer 1 (pH 7.00) and -177.4 mV for Buffer 2 (pH 10.00). If the ana- lyzer is working properly it should accept the cali- bration. The slope should be 59.16 mV/pH and the offset should be zero.

6.To check linearity, return to the main display and the pH/temperature/mV screen. Set the voltage source to the values shown in the table and verify that the pH and millivolt readings match the values in the table.

	Voltage (mV)	pH (at 25°)
	295.8	2.00
	177.5	4.00
	59.2	6.00
	-59.2	8.00
	-177.5	10.00
-295.8		12.00

SECTION 9.0

TROUBLESHOOTING

FIGURE 9-4. Simulating pH Input.

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