MEASURING PH WITH HIGHLY RESISTANT MEASURING DEVICES
FORT DETRICK FREDERICK MD
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PH measuring devices can be divided according to type into two main classes. In the first group, the measuring voltage is fed directly to the indicator dial after amplification. A directly coupled or a modulated amplifier can be used, a combination of both also being possible. The second main group works on the compensation principle. The measuring voltage is placed opposite a variable, calibrated compensation voltage and alternated until the difference voltage is zero. The control of the compensation current can be manual or automatic by means of a servo mechanism, the latter method often being combined with a registering device compensograph.
- Physical Chemistry
- Test Facilities, Equipment and Methods