A pH electrode that is properly manufactured and kept clean will retain its measuring integrity for quite a long time. The most common cause for pH measurement inaccuracies is an unclean or improperly cleaned electrode. This is very important to note because, during calibration, the instrument assumes that the electrode is clean and that the standardization curve created during the calibration process will remain a valid reference until the next calibration. pH meters on the market today will allow an offset of approximately ±60 mV. The deviation from 0 mV is not unusual, in fact it represents the true characteristics of the pH electrode. The deviation from 0 mV becomes a problem if it is the result of calibrating a dirty electrode.

This pH meter compares the characteristics of the pH electrode from one calibration to the next. In case of large variances in the electrode condition that can only be the result of a soiled sensor, these meters alert the user that the electrode needs to be properly cleaned prior to calibration and measuring.

Features

•  Enhanced Calibration Messages
•  Electrode Condition on LCD Display
•  Electrode Response Time on LCD Display
•  Calibration Alarm Time Out

Specifications

Range	pH	-2.00 to 16.00 pH; -2.000 to 16.000 pH
Range	mV	±699.9 mV; ±2000 mV
Range	Temperature	-20.0 to 120.0°C
Resolution	pH	0.01 pH; 0.001 pH
Resolution	mV	0.1 (±999.9 mV); 1 (±2000 mV)
Resolution	Temperature	0.1°C
Accuracy	pH	±0.01 pH; ±0.002 pH
Accuracy	mV	±0.2 (±699.9 mV); ±0.5 (±999.9 mV); ±1 (±2000 mV)
Accuracy	Temperature	±0.4°C
Calibration Check		status of electrode condition and response time, status of the buffer solution during calibration
pH Calibration		automatic, up to 5 points with 7 memorized values (pH 1.68, 4.01, 6.86, 7.01, 9.18, 10.01, 12.45)
Temperature Compensation		manual or automatic, -20.0 to -120.0°C (-4 to 248°F)
pH Electrode		HI 1131P, glass-body, single junction, refillable, BNC + Pin connector, 1 m (3.3') cable (included)
Temperature Probe		HI 7669/2W with 1 m (3.3') cable (included)
PC Connection		RS232 opto-isolated serial port
Data Logging		500 samples
Input Impedance		1012 Ohm
Power Supply		12 Vdc adapter (included)
Environment		0 to 50°C (32 to 122°F); RH max 95%
Dimensions		240 x 182 x 74 mm (9.4 x 7.2 x 2.9")
Weight		1.1 kg (2.4 lb.)