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Custom solutions for pressure

Wherever pressure sensors are needed, a solution can normally be found in the KELLER standard product catalogue

However, there are often great benefits to optimising a product specifically for integration and use in existing complete systems. In addition to outwardly identifiable components such as housing parts or plugs, this also includes the inner workings of the sensor. Keller by Instrotech offers many individual parts in-house and establishes close working relationships with their suppliers, enabling them to make a wide variety of modifications easily.


Shared Expertise for the Perfect Sensor Solutions

Keller customers are specialists in their field: they know the requirements and operating conditions best. Since 1974, KELLER has been harnessing the potential of piezoresistive sensor technology to see numerous challenging projects through to completion. In all of these projects, a mutual exchange of expertise was essential to their success. Sharing Keller’s knowledge is what enables them to find the best sensor solution.

Even applications that may appear trivial at first glance can prove highly complex upon closer analysis. By taking the actual usage conditions of the sensor into consideration right from the outset, Keller can achieve major improvements in effectiveness and durability. This holds true regardless of the application – from fill-level sensors in rainwater tanks to ultra-precise laboratory instruments and even rocket science.

Regardless of the task, expert advice from our sales engineers and developers is a vital piece of the puzzle. Whether an existing product can be used – possibly with suitable modifications – or a new development is needed depends entirely on the customer's project. Together, Instrotech and Keller look at the requirements to determine the properties needed for flawless measurement. Armed with many years of experience, we closely examine all the factors involved and their various interdependencies.


Measuring Ranges & Performance

Keller-MeasuringRange and PerformanceFirst, we define the basic sensor specifications such as overall measuring range, accuracy, calibration to specific measuring points and units of pressure, or scaling of the output signal. Products with a digital signal output have additional factors that also need to be determined, such as sampling rate or signal resolution. The values defined at this stage form the starting point for selecting components.

Bernhard Vetterli, KELLER’s Technical Director, says, “Thanks to our technological expertise, longstanding experience and mastery of the many processes involved in manufacturing pressure sensors, coupled with a high level of vertical integration, we can make even the impossible possible.”


Perfectly Tuned to the Ambient Conditions

Keller-Ambient-ConditionsAnother crucial requirement is considering the ambient conditions. Not only does this increase the service life of the sensor, but it is also an essential prerequisite for correct measurements. If the pressurised system operates with a large overpressure or with dynamic loads, the sensor design must be optimised for these particular demands. With some applications or neighbouring system parts, there is a risk of signal distortion or component failure due to vibration or shock. Temperature also has a major impact on all materials and their resistance. Complications can be caused not just by extreme temperature values but also by rapid changes in temperature. Another equally important factor is chemical resistance. The materials used for housings and seals must be carefully selected otherwise they risk being damaged by aggressive measuring media. External factors such as petrol fumes, UV radiation, salt water or microorganisms can cause problems. It is, therefore, essential that all relevant factors be considered. Of course, even finely tuned designs still have limits, and additional protective measures may be needed.

Stefan Fehr, Head of Quality Assurance KELLER adds, “Our experience has taught us that material and physics hardly know any limits when it comes to creating new challenges for us to solve.”


Mechanical Design

Keller-Mechcanical-DesignWhen designing a sensor, all the above points must be considered. A device's performance is heavily influenced by the sensor design, from the choice of the sensor chip and coupling medium to the materials and production techniques used. In addition, customers may have particular requests concerning shape and size, pressure connections, and so on. Of course, any specific requirements about the area of application must be complied with, along with all the applicable legal regulations and standards.

David Bollinger, Head of Mechanical Engineering at KELLER says, “Customer-specific constructions are an important driver of innovation and inspire us to develop new ideas and approaches to finding solutions. Ultimately, new findings are always incorporated into further developing and improving our existing product range.”


Electronics & Configuration

Keller-configurationThe main function of the electronics is to prepare the measurement signal and possibly save it and output it via a suitable interface. Customers can also request that application-specific calculations be integrated in the firmware or ask for special device and software configurations. Once again, other requirements depend on the environment, such as extended lightning protection, EMC, or explosion protection. Intrinsically safe products can also be specially configured to match the parameters of the customer's overall system.

Silvan Achtnich, Electronics and Software Development at KELLER says, “We develop electronic modules that get the best accuracy from our sensor elements and leave scope for your customer-specific algorithms.”


Electrical Interfaces & Connections

Digital interfaces can be configured for specific communication protocols, or modified to suit the customer's needs. Meanwhile, analogue interfaces also play a vital role in sensor technology. KELLER is highly experienced in developing application-specific solutions based on both principles, including devices with light wave and frequency outputs. For electrical connections, the necessary plugs can be integrated into the design, while cable outlets can be specified by the customer.

Daniel Hofer, KELLER’s Head of Product Management says, “The success of a project hinges on the exchange of information at the interfaces. We are committed to offering a wide range of protocols and electrical interfaces for seamless system integration and loss-free transmission of pressure values.”


In addition to customer logos, it is also possible to have functional markings applied to the product, either employing laser inscription or by printing information on labels. These may include part codes, serial numbers, data matrix codes or guide marks. Customers can also specify a colour-coding scheme for the connecting wires. For consumer products such as manometers, a personalised design that includes the customer's logo can be applied to the front panel.

Patricia Pedroso of Laserservice, says, “Our annealing marking technology guarantees high-resolution laser inscriptions that are resistant to acids as well as chemical and corrosive components, all without damaging the metal surface.”

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