Instrumentation Choices For Load Cells And Other Sensors

Aptifirst Ltd offers a wide range of load-cell strain gauge signal conditioning instruments from simple in-cell devices with analogue output or digital output, or with radio telemetry, and with varying degrees of process control functionality.

Many load cell weighing devices, and similar transducers for measuring parameters such as pressure, force and torque, are based upon strain gauges. These are small sensors bonded to a precision-machined surface; their resistance changes as the displacement of the surface alters as a function of the applied force. Strain gauges are usually mounted in sets of four to form a Wheatstone bridge circuit referred to as a strain gauge bridge. An “excitation voltage”, which can be AC or DC, and is usually between 3 and 15 volts, is applied to two opposite corners of the bridge, and the output signal is taken off from the other two corners of the bridge.

Amplifiers with analogue outputs include the ICA InCell Series, designed to fit inside a load-cell or other equipment, and are available in a range of models with different outputs and supply voltages, whereas the SGA amplifiers have a very high bandwidth (DC to 6kHz) and switchable filters, and are available for DC or AC supplies. Also, there is the PR490 compact, DIN-rail mounting load cell amp.

Alternatively, you may prefer a digital amplifier to communicate with computer or PLC control systems. The DCell Digital Strain Puck is designed, like the ICA, to fit inside a load-cell; alternatively there is a mini-PCB version, the DSC Digital Strain Card, including the new DSCUSB version, which connects directly to a USB port. Additionally, Aptifirst offers the PR486 with options of Ethernet, Profibus, DeviceNet, serial or analogue outputs, the LCA20 Intelligent load cell amplifier and process controller, and the SMW surface-mounting intelligent weighing indicator and controller.

The newly improved T24 Radio Telemetry system is modular, with increased range of up to 800m, input modules for strain gauges and load cells as well as for temperature, pressure, resistance, current, voltage and pulses and with data capture modules, data-logging software, solar power supply, displays, wind speed anemometer and other modules, provides a highly versatile solution for many integrated instrumentation applications.

For specific weighing and process control applications, Aptifirst offers instruments such as the ADW15 and ADP15 weighing and process controllers with firmware options for Batch Weighing, Loss-In-Weight, Fast-Fill-By-Weight, with many features and options.

As well as instrumentation systems, Aptifirst also supplies a range of load cells in a gamut of load ranges and mechanical configurations, and is always happy to consider requests for “special” applications. For example, we have recently supplied to an antipodean university some submersible (IP68) ALC06 in-line load cells for marine research work.

Additionally, Aptifirst supplies sapphire window optical process probes, accelerometers, dataloggers, precision extrusion dies for rheometry, capillary extrusion rheometers, consultancy and special purpose machinery and instrumentation.

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