5
2 General information
2
General information
2.1
Object of these instructions and purpose of application
The standard DIN EN 1434 describes the requirements for heat meters and their sub-components.
When combining sub-components (flow sensor, pair of temperature probes, computer unit) to form a
heat meter, the standard prescribes platinum RTD temperature probes according to the standard
DIN EN 60751 because these probes have sufficient measurement stability, accuracy, and interchange-
ability.
These days, the latest heat meters use various nominal values on the computer unit side (resistance
value at 0 °C). The nominal values are normally 100 Ω (Pt100), 500 Ω (Pt500), and 1000 Ω (Pt1000).
The RTD temperature probes from the type series 902428/30 and 902428/40 for direct mounting and
902438/30 and 902438/32 for installation in immersion sleeves are type-tested according to the Europe-
an Measuring Instruments Directive 2014/32/EU (MID) including Annexes I and MI-004. The paired tem-
perature probes are suitable for being connected to a computer unit for a heat meter and measuring the
difference between the inflow and outflow temperature in a heat exchanger system.
The temperature probes are made up of a corrosion-resistant protection fitting. The connecting cable is
permanently connected to the temperature probe.
In order to meet the metrological requirements of the European Measuring Instruments Directive 2014/
32/EU (MID) and the Annex MI-004, the temperature probes are calibrated at three temperatures and
paired according to a special mathematical process in order to comply with the tolerance for the tem-
perature difference. The lower limit for the temperature difference is 3 K.
2.2
Identification marking
Each temperature probe pair is equipped with a nameplate containing the following information:
•
CE identification marking with ID codes for the notified bodies appointed to certify module D (produc-
tion quality assurance)
•
Metrology identification marking, including the two digits for the year in which the identification mark-
ing was created
•
Logo for the owner of the type examination certificate
•
Type examination certificate number
•
Pair number/ID
•
Manufacturing date (year/calendar week)
•
Manufacturing location (in-house code)
•
Type number
•
Admissible measuring range (temperature, temperature difference)
•
Maximum pressure stage
•
Nominal value
•
Manufacturer's address
The inflow and outflow probes are distinguished by colored identification markings on the temperature
probe's cable (red: inflow, blue: outflow) or using an identification marking on the nameplate (V = inflow,
R = outflow).
