IMP-LR Low Range pressure transmitter

The IMP-LR pressure transmitter has been designed for applications where the IMP standard industrial pressure transmitter cannot cater for the pressure ranges.  The IMP is limited to 500mbar as it uses a ceramic based piezo-resistive pressure sensor but the NEW IMP-LR offers pressure ranges from as low as 25mbar through to 1000mbar gauge, absolute ranges also available on request.

Based on an Oil filled isolated diaphragm silicon pressure sensor the IMP-LR can offer accuracy of <0.25% as standard with the option of linearity correcting to <0.1% FS BFSL if required.  Being an isolated diaphragm silicon pressure sensor the transmitter can be used on both liquids and gases.  The sensor is installed in the stainless steel housing and sealed on an O ring which means by selecting the correct material these pressure transmitters be used on a wide variety of applications and medias.

The pressure transmitter is built in our factory in Aldermaston in a modular format so when required it is taken from stock pre-assembled.  We then calibrate the sensor using the automated calibration system via the ASIC based digital electronics.  This means there are no internal pots giving a very stable output with good long term stability.  The transmitter build is finished by simply selecting the correct electrical connector and issuing the calibration certificate which comes as standard with every sensor.  The choice of electrical connections include both small and large Hirschmann style plug & sockets, M12 and binder connectors, IP66 and IP68 cable glands and MIL-Spec connectors also.

Available outputs include the standard 4-20mA current and a variety of voltages both ratiometric and non-ratiometric all of which are temperature compensated as standard.  The IMP-LR is also suitable for all types of installation and complies to the latest standards in CE, EMC and RFI protection.

Product Datasheet: IMP-LR Low range pressure transmitter

Product Page:  Low range pressure transmitters

If you have any applications you wish to discuss or any questions questions regarding this product then please contact sales here sales@impress-sensors.co.uk

IMP-LR – Low pressure transmitter from 25mbar! is a post from: Impress Sensors

Some specific advantages can be gained from using pressure transducers that operate on the Linear Variable Differential Transformer (LVDT) principle. Here, a pressure responsive element is directly coupled to the core of a linear LVDT.

Pressure Sensors integrate LVDT Technology

An LVDT is an electro-mechanical device that produces an electrical output that is linearly proprtional to the displacement of a moveable core. It consists of a primary coil with two secondary coils placed on either side of the primary coil. A rod-shaped soft magnetic core inside the coil assembly provides a path for the magnetic flux linking the coils.

When the primary coil is energised by an alternating current, source voltages are induced in the two secondary coils. The secondary coils are connected in series with the start of each winding being connected together. This arrangement produces a net zero signal output from the secondaries when the induced voltages are equal in each coil. This condition occurs when the core is centrally disposed between the two secondaries. A movement of the core leads to an increase in magnetic coupling to the coil in the direction of movement and a reduction in of magnetic coupling to the other coil producing a net output signal from the connected secondaries. Movement in the opposite direction produces an identical signal output but of opposite phase.

To form a pressure transducer, the core displacement of the LVDT is produced by the movement of a metallic pressure responsive diaphragm.

Some LVDT pressure transducers are fitted with a single, precision metallic diaphragm with over range pressure protection stops as the pressure-responsive element. This arranagement allows the manufacture of differential, gauge and absolute transducers, which all employ a common design philosophy.

The distinct advantage of using an LVDT transducer is that the moving core does not make contact with other electrical components of the assembly, as is the case with other types. This means an LVDT transducer offers high reliability and long life.

The LVDT design also lends itself very well to easy modification in order to fulfil a whole range of different applications in both research and process engineering.

Positive Over-pressure

An LVDT gauge-type pressure transducer lends itself very well to being protected from damage by positive over-pressure. The sensor’s safe limits are normally much greater than those specified by the manufacturer and unrivalled by alternative technologies. Often, the sensor will still operate above the specified over-pressure limit, but at a reduced accuracy. In contrast, silicon and thick-film pressure sensors do not exhibit this level of over-pressure capability.

Rupture Integrity

Unlike silicon and thick film pressure sensors, LVDT pressure transducers provide process containment for applied static pressures of up to 400bar or higher. Special welding techniques are used to improve rupture integrity, supported by an over-pressure stop. In addition, the diaphragm material can be relatively thick, offering enhanced durability and improved resistance to pin-holing (corrosion).

Shock Loading

LVDT pressure transducers can be impact shock-loaded in all three axes without sacrificing the performance of the sensor. The diaphragms are not made from brittle materials and so failures due to shock loads are rare.

Fluid Fill

Process compatibility is also a key requirement when sourcing a suitable pressure transducer. With LVDT pressure sensors, flush diaphragms can be provided rather than fluid-filled units. This offers enhanced process compatibility and does not limit the temperature range. In addition, if the pressure sensor is required to perform in a hygiernic application such as a dairy or food processing application, a low cost silicon-filled sensor will require a barrier of some sort to prevent conatmination. In contrast, the design of an LVDT pressure sensor makes it inherently suited to hygienic, FDA-compliant applications.

Process Interface Options

LVDT pressure sensors open up a wide range of process interface and wetted material options for the user. With sufficient understanding of the application, the sensor manufacturer is able to optimise the measurement solution at the lowest cost.

Transmitter Electronics

LVDT pressure and level transmitters enable the user to adjust both zero and span settings. Analogue and digital signal processing types are available. Most analogue transmitters will offer zero and span adjustment, square root option, time constant and ±100 per cent offset adjustment.

Digital electronic types offer local configuration of zero and span, along with the ability to turn on or off the instrument preset non-linear function. Digital types can normally be configured via an integral communication port.

Submersible type LVDT pressure sensors normally use digital signal processing and have the option of either a simple single wire configuration port that allows zero and span calibration together with the ability to turn on or off the instrument preset non-linear function, or full RS485 communication that enables full configuration of the transmitter.

LVDT Pressure Transducers for the Nuclear Industry

In the nuclear sector, LVDT pressure transducers are utilised in reactor research and development work; leak detection on nuclear transport flasks; detection of leakage from Magnox storage ponds; monitoring material storage pond levels; storage room pressure monitoring; level measurement in effluent treatment works; and glove box gas handling systems. LVDTs are even used in weapons de-commissioning, where the sensor must withstand highly aggressive chemicals such as Hydrobromic Acid and where radiation immunity is critical.

LVDT pressure transducers are generally favoured by the nuclear industry because they offer distinct advantages over alternative pressure sensor designs.

LVDT tranducers provide high immunity to radiation and can be stable to 10 exp6 rad, with some manufacturers offering versions that allow up to 10 exp12 rad without damage to the sensor.

LVDT sensors can also withstand higher temperatures, with high radiation continuous working options typically available up to 200 deg C.

LVDT sensors also benefit from the fact they can have remote electronics up to 1,000 metres or more of cable between the sensor and the signal conditioning electronics. This allows the sensor to operate in extreme radiation, temperature and high magnetic fields, conditions that would normally damage the conditioning electronics.

In LVDT sensors, the segregation of the transducer from the pressure-responsive element enables many specialist materials to be used for compatibility with the process fluid. Manufacturers can therefore produce sensors with Tantalum, Hastelloy, stainless steel, Monel, Inconel and PTFE sintered coatings.

Products Page: LVDT based pressure sensors & transmitters

For more information on these products please contact Impress sales on sales@impress-sensors.co.uk

Pressure sensor utilises LVDT technology! is a post from: Impress Sensors

Pressure sensors vary considerably in their design technology used, performance and application.  Pressure sensors often can be referred to as pressure transducers, pressure transmitters, pressure indicators or pressure switches – are used to measure the pressure of gases and liquids (fluids).

Pressure is an expression of the force and is normally stated in terms of force per unit area. A pressure sensor will generate an electrical signal relating to the pressure imposed. This signal is either analogue or digital in more modern designs, although optical, visual and auditory signals are also common.

Pressure sensors, basics of pressure measurement

Industrial pressure transducers normally have a diaphragm type design that uses strain gauges, which are either bonded to, or diffused into it, with the strain gauges acting as resistive elements. Under the pressure-induced strain, the resistive values change. In capacitive technology, the pressure diaphragm is a single plate of a capacitor that changes its value under pressure-induced displacement. These are probably the most common technologies used in industrial applications for their favourable price/performance ratio.

Pressure is measured against a reference, which greatly depends on the application and installation of the sensor. Depending on the relevant pressure, the term ‘absolute’ is used when the reference is vacuum; ‘gauge’ is used where the reference is atmospheric pressure; and ‘differential’ is used where the sensor has two ports for the measurement of two different pressures.

Pressure sensors are used in a wide variety of applications for control and monitoring purposes. Pressure sensors can also be used to indirectly measure other variables such as liquid or gas flow (in conjunction with an orifice plate), speed, fluid level and also altitude.

Due to the wide range of technologies available, pressure sensors vary considerably in their design, performance, application and cost. Every technology has its own benefits and reasons for selection within an application.

When used directly to measure pressure, applications include meteorology instrumentation, aerospace and defence, research and development, automotive and other machinery or equipment that has pressure functionality implemented. Other applications for pressure sensors include hydraulic and pneumatic systems, water depth, offshore & marine, waste water & sewage, oil & gas exploration, nuclear, medical, food and beverage processing, tank level/contents, HVAC systems, agricultural equipment, environmental monitoring and chemical & processing plants.

Pressure Products Page:  Impress Sensor pressure products page

Basics of pressure measurement is a post from: Impress Sensors

DSK 701C Capacitive Pressure Sensor

A new range of ready-to-mount pressure sensor modules for OEMs is now available that customers can integrate into their machine designs and instrumentation, including equipment that needs to be ATEX-certified for hazardous environments.

The DSK 701C pressure sensor module from Impress Sensors & Systems Ltd is a ready-to-assemble capacitive ceramic pressure sensor module that offers very low pressure ranges (20 bar down to 60mbar) but extremely high overpressure resistance.

An additional benefit to OEMs is that the module is ATEX-prepared for Zone 0: II 1G Ex ia IIC T4 certification. This means the OEM can simply install the sensor module straight into a housing or on a machine, knowing that the module itself will require no additional, separate ATEX certification.

Designed specifically as a cost effective module for OEMs and machine builders, the DSK 701C can also be configured and programmed by the customer via an integrated RS232 interface. An optional configuration kit is available, which enables the OEM to reconfigure sensors for different end user applications. The module is simply connected to a PC via the RS232 interface and menu-driven programming software is used to calibrate pressures, configure starting points and end points of the pressure range, damping and offset adjustment.

The pressure sensor module will have a wide appeal amongst OEMs and specialist machine builders, from waste water, sewerage and marine applications, through to manufacturers of inkjet printers. Some customers may already have their own electronics but require a ready-to-mount, low cost pressure sensor module to complete their system solution.

The DSK 701C has a ceramic membrane and offers a high turn down ratio of 10:1, without sacrificing accuracy. For example, a 1 bar rated sensor module can be turned down to 100mbar, but the accuracy remains at 0.1% and overpressure of 8bar is permissible.

The modules are available in gauge and absolute versions with a 4… 20mA output signal. Response time is 120ms (without electronic damping) and operating temperature range is from –40 deg C to +125 deg C. The unit is supplied with a PTFE filter as standard, with a brass venting tube option also available.

Product Datasheet: DSK 701C Capacitive pressure sensor

Product page: Sensing Element products page

For more information on the DSK 701C, please call the sales department on 0118 981 7980 or visit the website at www.impress-sensors.co.uk

ATEX-prepared Capacitive pressure sensor modules is a post from: Impress Sensors