Differential pressure measurement and control - transmitters

The DE03 Electronic Differential Pressure Transmitter combines electronic measurement with a rugged sensor design, resulting in high accuracy, high differential and static rating, and ability to handle difficult media. It is available with local digital readout and electronic limit detection relays, with measuring range of 0 – 40 mbar to 0 – 25 bar. DE03 Transmitters are suitable for a wide range of applications. All three diaphragms are fully protected against excess differential pressure in either direction, and also against high static pressures.

The differential pressure transmitter DE13 for differential, negative and positive pressure measurement using a diaphragm system with liquid filling. The instrument transmits a standard electrical signal. The pressures to be compared each act on an outer flexible stainless steel isolating diaphragm. They are transferred to the sensing diaphragm by the pressure transfer fluid. When pressures are equal on both sides of the sensing diaphragm, it is at zero position. Pressure difference across the sensing diaphragm causes it to deflect away from the higher pressure side, resulting in linear displacement of the LVDT core. This displacement is sensed by the LVDT’s coils, and converted by an electronic module to an output signal proportional to the differential pressure. Thus, all three diaphragms are fully protected against excess differential pressure in either direction, and also against high static pressures.

The transmitter DE15 serves to record the filling level or the content of upright or flat cylindrical tanks for industrial gases. The corresponding differential pressure of the filling level is measured. An additional integrated pressure sensor records the operating pressure of the system independent of this. The application scope comprises filling level equipment on closed tanks, in particular in the cryogenics field. The measuring system comprises two pressure chambers that are separated by a diaphragm. Differential pressure in one of the chambers leads to a proportional displacement of the diaphragms. This movement is transferred to an inductive displacement transducer and is converted into a 4…20 mA output signal by the downstream electronics. There is a ceramic sensor with a DMS bridge installed in the (-) side of the device. The current pressure changes the form of the ceramic membrane and leads to a proportional change of resistance in the DMS bridge. This change of resistance is converted into a 4…20 mA output signal by the downstream electronics.

Measuring transmitter DE16 for overpressure, partial vacuum and differential pressure. This series is suitable for various measuring applications in the field of industrial and sanitary techniques. Typical applications are measurement of differential pressure between forward- and returnflow in heating systems, monitoring of filters, blowers and compressors. Main Features are overpressure protection, rugged design, maintenance and wear free inductive pick-up, multiple applications. This transmitter is based on a rugged and uncomplicated diaphragm movement, suitable for overpressure, partial vacuum and differential pressure measurement. The operating principle of the system is identical in all three applications. In a state of equilibrium, the forces of the springs on both sides of the diaphragm are balanced. The pressure or differential pressure to be measured creates an unbalanced force of the springs for the measuring range until a new equilibrium is reached. A centre-mounted tappet transfers the motion of the diaphragm system to the core of an inductive displacement transducer.

The DE23 is a differential pressure transmitter for measuring very small overpressure, under-pressure and differential pressure in neutral, non-corrosive gaseous media.A centre-mounted tappet transfers the motion of the diaphragm system to the core of an inductive displacement transducer. Typical applications are filter equipment, precision air channel measurements, low-pressure measurement for building automation, clean room pressure equalisation, burner under-pressure measurement, furnace-circulating air controls. The basis of this transmitter is a sensor element with a produced differential condenser made with silicon-glass technology. The active pressure generates changes in capacity that is evaluated by the device's electronics and transformed into an analogue signal 4 … 20 mA or 0 … 10 V. The measuring channel are identical in the 2-channel models.

The DE25 is a differential pressure transmitter for measuring over-pressure, under-pressure and differential pressure in neutral, non-aggressive gaseous media. Typical applications are air conditioning and ventilation technology, filter equipment, construction and mechanical engineering. The basis of this transmitter is a piezo-resistive sensor element. The pressure that is to be measured acts directly onto a silicon diaphragm equipped with piezo-resistive resistors. The active pressure generates changes in resistance that are evaluated by the device's electronics and transformed into an analogue signal. The output signal is usually available as a current or voltage signal.

The DE27 is a multi-functional differential pressure transmitter. It is suitable for measuring overpressure, under-pressure and differential pressure in dry and neutral gaseous media. Important characteristics are robust, resistant to overpressure and maintenance-free, signal output with the option of spreading and inverting the characteristic, curve with any offset witghin the measuring range, all parameters and measuring point protocols are configured with a transmitter PC Interface EU03. Typical applications are monitoring of automatic roll filters, extraction systems etc., draft measurement in chimneys, flow and control pressure measurements. The basis of this transmitter is a piezo-resistive sensor element. The pressures to be measured directly act on a silicon diaphragm equipped with piezo-resistive resistors. Changes in pressure generate proportional changes in resistance, which is evaluated by the device's electronics and transformed into signals on the optional display, and converted into an output signal. The output signal, which is optionally available as a current or voltage signal can be dampened, spread and inverted. Configuration is realised via a Transmitter PC Interface (EU03) that is available as an accessory.

The DE28 is a measuring transducer for measuring non-aggressive gas-like and fluid media that is neutral to over-pressure, under-pressure and differential pressure. Always check the media compatibility with the manufacturer if used with potentially aggressive media. In the standard model, the device is suitable for many measuring tasks in all industrial or sanitary sectors. The DNV type-tested models are suitable for use on ships in machine rooms, control rooms and pump rooms. Please see the following table for details about the application place. Typical applications are differential pressure measurements between the supply and return on heating systems, monitoring of filters, fans and compressors, ship applications (only DNV model).

The DE38_LCD digital differential pressure transmitter / switch with colour change LCD is a transmitter with a diaphragm meas-uring device and is suitable for measuring over-pressure, under-pressure anddifferential pressure in neutral liquid and gaseous media. The switching device is based on a robust and durable diaphragm measuringunit. The pressures to be compared have an effect on a spring mounted meas-uring diaphragm that is in an idle state when the pressure is equalised. In case of a pressure difference, a force acts on the measuring diaphragm. The force acting on the measuring diaphragm causes it to be moved towards theside of the lower pressure until the spring forces compensate this force. The movement of the diaphragm is transferred via a tappet into the core of theinductive displacement sensor. The electronics integrated into the device evalu-ate this movement and transform it into signals on the display, switch contactsand optionally into an analogue output signal. The can be dampened, spread,inverted and transformed via a table function even if it is non-linear.

Digital differential pressure transmitter / switch with colour change DE38_LED is a diaphragm measuring device and is suitable for measuring over-pressure, under-pressure and differential pressure in neutral liquid and gaseous media. The switching device is based on a robust and durable diaphragm measuring unit. The pressures to be compared have an effect on a spring mounted measuring diaphragm that is in an idle state when the pressure is equalised. The force acting on the measuring diaphragm causes it to be moved towards the side of the lower pressure until the spring forces compensate this force. The movement of the diaphragm is transferred via a tappet into the core of the inductive displacement sensor. The electronics integrated into the device evaluate this movement and transform it into signals on the display, switch contacts and optionally into an analogue output signal. The can be dampened, spread, inverted and transformed via a table function even if it is non-linear.

The devices of the series DE39_LCD can be used as display and switching device for measuring differential pressure of gaseous and fluid media. Its sturdy design also allows heavily contaminated media to be used. Always check the medium compatibility. The pressure is measured by two integrated ceramic sensor elements whose measuring signals P+ and P- are analysed by a digital measuring transducer. The analysis allows two independent switching points to be set and makes two programmable output signals available. The measurements can be shown together, separately or alternately. The nominal pressures of the integrated sensors and the differential pressure measuring range are set permanently exworks and stated on the type plate. The unit works in two operating modes: Differential pressure and 2-channel.

Digital differential pressure transmitter DE39_LED with internal pressure sensors. Display and switching device for differential pres-sure of gaseous and fluid media. The device is based on an electronic evaluation cir-cuit that analyses the measuring signals of two integrated ceramic pressure transmitters. The signals of the pressure transmitter can be displayed sepa-rately for checking purposes. The integrated pressure sensors work with ceramic pressure measuring cells. The signals are digital-ised and made available to the analysis unit for further processing. The main task is to calculate the differential pressure that can be displayed and analysed. The anal-ysis allows the configuration of two independent switching points and the provision of an output signal that is proportional to the differential pressure. The rated pressures of the integrated sensors and the differential pressure measuring range are set permanently ex-works and shown on the type plate.

The pressure chamber of the DE40 can be made of brass or stainless steel. There are also several options for the process connection. The differential pressure transmitter DN40 is suitable for measuring over-pressure, under-pressure and differential pressure in basically neutral fluids and gases. It is suitable for all measuring tasks in industrial or sanitary sectors. The differential pressure transmitters of this type series DN40 are equipped with a non-sensitive ceramic pressure measuring cell. The measuring bridge is pressed directly onto the ceramic membrane by means of a thick layer technology. The measuring pressure acts on the membrane which in turn deforms. In turn, the bridge resistors change and a voltage signal that is proportional to the measuring pressure is created. The electronics integrated into the transmitter housing convert this signal into a uniform signal 0...10V or 4...20mA.