Delta OHM DO 9709, Инструкция по эксплуатации

Страница: 29 / 82

HOW TO MEASURE
1. Switching on the instrument with the ON/OFF key.
* This operation enables the automatic cutout timer.
* If you wish power supply without automatic interruption, press the HOLD and ON/OFF keys
simultaneously and keep the HOLD button held down for the duration of the switching-on routi-
ne. The battery symbol flashes at a frequency of 1 Hz, indicating that the Auto Power Off func-
tion is disabled.
* When the instrument is switched on all the numbers and symbols light up for a few moments,
allowing you to check that all the display segments are working.
* Immediately afterwards the instrument shows the CAL message on the top display and, on the
bottom display, the calibration coefficient of the dissolved Oxygen probe (a value between 500
and 1500). This enables you to check the efficiency of the probes: a calibration coefficient close
to 1500 indicates that the current generated by the probe is amplified by 1.5, the probe is run-
ning low and is no longer able to transform the Oxygen present in the water into current to be
measured.
* After a few moments it moves on to normal operation.
2. Checking display.
* In normal operation, the instrument shows the measurements of the dissolved Oxygen concen-
tration in mg/l on the top of the display and, on the bottom of the display, the temperature found
in measuring the dissolved Oxygen expressed in °C.
* Normally only the dissolved Oxygen probe is connected to the instrument; temperature measu-
rement refers to the sensor inside the probe: If the temperature sensor is disconnected or
damaged, the instrument continues working, using the default temperature for calculations
referring to the dissolved Oxygen. The message E03 alternating with the dissolved Oxygen
measurement indicates that the default temperature is being used.
* If a temperature probe (4-wire Pt100 probe or series TP 870) is inserted in input B, the tempe-
rature measurement is shown at the bottom of the display and is used for calculations referring
to the dissolved Oxygen. This operating mode must not be preferred to the one that uses
the temperature measurement obtained by the sensor inside the dissolved Oxygen pro-
be.
It must be considered with the sensor inside the dissolved Oxygen probe damaged or when
you want to measure only the temperature of the water that is being examined.
* If the dissolved Oxygen measurement (both the concentration and the saturation index) is abo-
ve the measuring limits or the measurement probe is not correctly connected, the measure-
ment error signal appears (Err): check the probe and the connector.
* The dissolved Oxygen measurement gives an error signal if the temperature measure-
ment exceeds the range 0÷50°C: outside this range the saturated concentration of dissolved
Oxygen and the steam pressure of the water are not calculated and the water salinity is not
compensated.
* The final cause which may lead to an error in the dissolved Oxygen measurement is the incor-
rect measurement of atmospheric pressure, indicated by the instrument by means of the mes-
ENGLISH
107