MODEL 399VP pH/ORP SENSOR | SECTION 5.0 |
| MAINTENANCE |
SECTION 5.0.
MAINTENANCE
5.1GENERAL
5.2AUTOMATIC TEMPERATURE COMPENSATOR
5.3pH ELECTRODE CLEANING
5.4ORP PLATINUM ELECTRODE CHECK
5.1GENERAL
The Model 399VP sensor is a disposable type sensor and therefore requires minimum maintenance. The sensor should be kept clean and free of debris and sediment at all times. The frequency of cleaning, by wiping or brush- ing with a soft cloth or brush, is determined by the nature of the solution being measured. The sensor should be removed from the process periodically and checked in buffer solutions.
WARNING
BEFORE REMOVING THE SENSOR, be absolutely cer- tain that the process pressure is reduced to 0 psig and the process temperature is lowered to a safe level!
If the sensor will not calibrate, refer to your analyzer/ transmitter instruction manual for proper test procedures. If it is then determined that the sensor has failed, it should be discarded and replaced.
5.2AUTOMATIC TEMPERATURE COMPENSATOR
The temperature compensator element is temperature sensitive and can be checked with an ohmmeter. Resistance increases with temperature.
Resistance varies with temperature for a 3K and Pt100 element and can be determined according to Table
RT = Ro [l+R1
Where RT = Resistance
T = Temperature in °C
Refer to Table
TABLE
TEMPERATURE COMPENSATION ELEMENTS
Temperature | Ro | R1 | |
Compensation Element | |||
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3K | 2934 | .0045 | |
Pt100 | 107.7 | .00385 | |
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TABLE
OF AUTO T.C. ELEMENTS
| Resistance | |
Temperature °C | (Ohms) ±1% | |
| 3K | Pt100 |
0 | 2670 | 100.0 |
10 | 2802 | 103.9 |
20 | 2934 | 107.8 |
25 | 3000 | 109.7 |
30 | 3066 | 111.7 |
40 | 3198 | 115.5 |
50 | 3330 | 119.4 |
60 | 3462 | 123.2 |
70 | 3594 | 127.1 |
80 | 3726 | 130.9 |
90 | 3858 | 134.7 |
100 | 3990 | 138.5 |
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