Bedienungsanleitung SDT43
BDA Serie SDT43 (Stand Jan. 2018)
Seite 31
1.
INTRODUCTION
The SDT43 is a solid-state pressure- and level transmitter based upon a piezoresistive
silicon sensor, with a very high burst pressure. The sensor element is mounted in a stainless
steel foot. Inside the foot also a temperature sensor is mounted to measure the process
temperature. The temperature sensor is used to create an active temperature compensation.
A strong stainless steel "flush" diaphragm protects the sensor from the process medium. A
very small amount of special oil fills the chamber surrounding the sensor and transfers
pressure from the flush mounted diaphragm to the sensor.
Pressure on the sensor element creates a very small deflection of the silicon substrate and
bridge network. The resulting strain in the silicon resistors causes a change in the bridge
resistance that is proportional to the pressure applied. The transmitter electronics detects this
change in bridge resistance and converts it into 4-20 mA. The amplifier system is based on a
single Integrated Circuit, which ensures a perfect linearity in the 4-20 mA output, all within an
accuracy of 0.075 %.
Due to the
flush diaphragm technology
the long term stability is perfect.
1.1
DESCRIPTION SDT43
The SDT43 is specially designed with a flush mounted diaphragm so they fully meet the
needs of the food, pharma and chemical industries. Standard the wetted parts are made of
SS 316 L, other materials are available, like Hastelloy C. Various process connections can
be delivered, such as Tri-Clamp (1,5”, 2” and 3”), SMS (1,5” and 2”), dairy milk couplings (DN
25, 40 and 50), flanges (DIN and ANSI) and sanitary weld-on nipples (ø 48, 62 and 85 mm.)
All transmitters are fully temperature compensated, which means that different process
temperatures have almost no effect on the accuracy of the output signal. If an error occurs,
the sensor can be repaired. For optimum accuracy, the sensor must be sent back to the
manufacturer.
1.3
BAROMETRIC REFERENCE
The SDT43 is in basic a so-called "relative transmitter" which means that barometric changes
will not affect the zero (4 mA). The venting is placed in the cover of the electronics housing
and is the filter for the barometric reference to atmospheric pressure. The venting must be
kept clean.
