9
1.4 Apparatus components
1.4.1 According to version and delivery set the apparatus is composed of:
convertor unit with temperature sensor;
electrodes as shown in Table 1.1; and
tools and accessories kit.
1.5 Design and operation
1.5.1 pH-meter general data
MAPK-903 (MAPK-903/1) pH-meter is a small-size microprocessor
instrument used to measure pH or U and temperature of aqueous solutions.
Measured temperature, pH and U (depending on measurement conditions) are
read from a digital liquid crystal display (hereafter display) with the least significant digit
0.1
С; 0.001 pH or 0.1 mV.
The pH-meter makes it possible to enter the measurement results in an
electronic scratchpad.
According to the version, the pH-meter may use a combined electrode or
individual electrodes (measuring electrode and reference electrode).
Note
To monitor water chemistry at heat engineering facilities, based on
data in MU 34-70-114-85 Document the pH-meter may reduce pH-value pH
t
measured at temperature t to pH
25
value that corresponds to the value at
temperature of 25
С.
pH
t
values may be reduced to рН
25
in the range from plus 5 to plus 50
С.
The reduced рН
25
value may be read from the display.
The pH-value of highly dilute alkaline and acid solutions and analyzable fluid
temperature relationship implemented in the pH-meter is graphically shown in
Attachment B
.
1.5.2 pH-meter operating principle
The pH-meter operation is based on the potentiometric analyzable solution
pH measuring method.