Electricity and Control August 2024

SENSORS + SWITCHES

Customised solutions in pressure sensors

Instrotech, local representative of KELLER, a Swiss-based market leader in the production of isolated pressure transducers and transmitters, supplies the wide range of KELLER pressure sensors as well as customised solutions.

W herever pressure sensors are needed, a solu tion can normally be found in KELLER’s stand ard product catalogue, but there are often great benefits to optimising a product specifically for integration and use in existing complete systems. In addition to out wardly identifiable components such as housing parts or plugs, the inner workings of the sensor can be optimised. Instrotech offers many individual parts in-house and works closely with the supplier, so it can make various modifica tions with ease. Shared expertise Instrotech’s customers are specialists in their field: they know their requirements and operating conditions best and KELLER understands this. Since 1974, KELLER has been harnessing the potential of piezoresistive sensor technolo gy to see numerous challenging projects to completion. In these projects, a mutual exchange of expertise has been essential to their success. Sharing KELLER’s knowledge is what enables Instrotech to find the best sensor solution for its customers. Even applications that may appear simple at first glance can prove highly complex on closer analysis. By taking on site usage conditions of the required sensor into considera tion from the outset, KELLER can implement improvements in the effectiveness and durability of the solution. This holds true whatever the application – from fill-level sensors in rain water tanks to ultra-precise laboratory instruments. No matter the task at hand, expert advice from the company’s sales engineers and developers is an impor tant part of the puzzle. Deciding if an existing product can be used – possibly with suitable modifications – or a new development is needed, depends entirely on the applica tion project. Together, Instrotech and KELLER look at the requirements to determine the properties needed for flaw less measurement. With their many years of experience, the teams look closely at all the factors involved and their various interdependencies.

Various specifications must be considered in determining the right solution for each application. Measuring ranges and performance First, they 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 ad ditional factors that need to be determined, such as sam pling rate or signal resolution. The values defined at this stage form the starting point for selecting components. Bernhard Vetterli, Technical Director at KELLER, says, “With our technological expertise, long experience and mastery of the many processes involved in manufacturing pressure sensors, as well as a high level of vertical inte gration, we can make what sometimes seems impossible, possible.” Tuned to ambient conditions Another crucial requirement is considering the ambient conditions. These can inform design to provide for a longer service life for the sensor and are essential for delivering 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 by extreme temperatures and by rapid changes in temperature. Another important factor is chemical resist ance. The materials used for housings and seals must be carefully selected, so they are not at risk of being damaged by aggressive measuring media. External factors such as petrol fumes, ultraviolet radiation, salt water or, in some en vironments, microorganisms, can also 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.

As the local representative of market leader KELLER, Instrotech supplies a wide range of KELLER pressure sensors.

20 Electricity + Control AUGUST 2024