Elgas DATCOM, Operating Instructions Manual

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8
Metrological Features
138
8 Metrological Features
8.1 Temperature Measurement
To measure temperature, the device uses the EDT 101 digital transmitter with the PT1000
temperature sensor.
Mechanically, the transducer consists of a sensor in a 5.7 mm stainless steel shank with a length
of 50 mm from which the cable is routed. A part of the cable is a plastic cylindrical case with
electronics.
200 64
17
5.
7
50
Fig. 66 Transducer dimensions
The temperature is measured using a platinum resistance sensor whose output signal is fed to an
analogue-to-digital high-resolution corrector input. After converting to digital, the data is
processed by a microprocessor that corrects nonlinearity based on calibration data. The
calibration data is stored to EEPROM memory when the transducer is manufactured. The
transmitter communicates with the device via the RS485 communication interface.
The temperature measurement range is -25°C to +70°C or -40°C to +70°C. The measurement
period is common to both temperature and pressure measurements and can be set by the user
from 1s to 30s. The temperature measurement units are selectable by end user.
The temperature sensor replacement is protected by the manufacturer's seal (metrological seal)
and can only be performed by an Authorized Service Centre (ASC).
8.2 Pressure Measurement
The pressure is measured using the digital EDT 96 transducer. The transducer includes a piezo-
resistive silicon sensor with a durable stainless-steel diaphragm. The device electronics corrects
the non-linearity and temperature dependences of the pressure transducer based on the
calibration data stored in the transducer memory. The measuring range of the pressure
transducer must be specified by the customer when ordering the device. The supplied pressure
ranges are specified in Section 3.6.2.
The measurement period is common for both temperature and pressure measurements and can
be set by the user within the range from 1s to 30s. The pressure measurement units are
adjustable.
The temperature transducer replacement is protected by the manufacturer's seal (metrological
seal) and can only be performed by an Authorized Service Centre (ASC).
8.3 Compressibility Calculation
8.3.1 PTZ, TZ Conversion
The compressibility factor K is calculated from the gas composition specified in the parameters