How to choose the right pressure or thermal sensor for your application
By Dan Herzog, global product line director, pressure and thermal products, Honeywell Sensing and ContrElectronics
Choosing the right sensor for a particular application can be challenging. A sensor that is considered reliable in the packaging industry may not be able to withstand the ruggedness of a welding application. The key to sensor performance is to apply the appropriate sensor to the right application.
There are three things designers should be aware of when specifying-in sensor products: accuracy requirements, packaging requirements and environmental concerns. Different applications have different accuracy requirements; however, the more accurate the sensor is, the less time is generally required for application design. Packaging requirements are also specific to each application and choosing the wrong package can add cost to the overall assembly. Working with the supplier’s engineering team can help ensure the right package is selected.
Knowing the overall environmental conditions of an application is also important for designing a reliable product. For example, if condensation is a possibility in the application, choose a sensor that is liquid compatible.
A sensor platform approach is Honeywell’s way of offering a variety of packaging, pressure ranges and porting options. This gives design engineers more flexibility in system design. A platform approach can also improve overall system efficiency by matching the performance of the sensor to the application.
So, how do you select sensors that address multiple performance requirements? Here is a guide to finding just what you’re looking for based on your performance requirements or design needs.
First, decide what the application for the sensor is. Then, you’ll need to ask some of these basic questions, such as, how extreme are the temperatures or corrosive nature of the media being measured? Is the environment a vibration challenge? What is the pressure range that needs to be measured in psi, bar, inches of water, etc.? How much time are you willing to devote to the integration of the sensor, or must it be ready to implement and forget? What is the pressure type (gage, absolute, differential)? How accurate does the pressure measurement need to be? And, just as important, what are the size and price constraints?
Deciding on the right sensor involves knowing what you need, and not paying for what you don’t. From board-mounted pressure sensors to heavy-duty pressure transducers, each sensor type addresses specific needs, requirements and cost targets.
For example, if you require ease of integration on a pcb, porting and housing options and small size at an economical price point, an unamplified/uncompensated basic board-mounted pressure sensor would be the best option.
When selecting and implementing pressure sensors into designs, the following are important features:
• Very low drift over time or temperature and humidity extremes
• No need to calibrate after mounting to a pcb
• Temperature compensated and calibrated
• Custom calibration availability
• An extremely tight and consistent accuracy specification
• A wide variety of package styles and options with the same performance specifications
After basic board-mount pressure sensors, the next level of pressure sensors is designed for those who want to leverage their calibration and amplification. These sensors have less part interchangeability and are already temperature compensated, providing the ability to retain a high degree of stability, accuracy and repeatability. Ranging from 1psi to 150psi (60mbar to 10bar), these pressure sensors will operate as specified from -40°C to 125°C.
The next level of pressure sensor is amplified, compensated, and can be used as is without further calibration. The HSC and SSC TruStability pressure sensors offer a tight accuracy and small form factor. They have low power consumption which provides extended battery life and promotes energy efficiency. This type of pressure sensor is typically used for monitoring and control of industrial and medical pneumatic flow and system pressure for precise and efficient performance. These higher-end board-mounted pressure sensors should adhere to the moisture sensitivity level 1 requirement to avoid the thermal and mechanical damage during solder reflow processes that lesser rated products often incur.
One aspect of selecting the correct pressure sensor for your job is finding a supplier that is truly a one-stop shop. Regardless of capability, quality and reliability should be a key component of all its product offerings, no matter the price.
There are many considerations when selecting pressure sensors to meet the requirements at hand. Fortunately, today’s sensors span a wide range of options—from basic ‘no frills’ pressure sensors to heavy-duty pressure transducers ideal for the harshest of environments.
Platform sensors provide custom calibration for specific airflow and pressure ranges, and offer a variety of mounting, size, and packaging options. By better matching the pressure or airflow ranges to the application, the end result is a more accurate end-product. This is achieved by improving the overall resolution of the measurement.
Honeywell provides value-added products that are built on pressure and thermal sensing platforms combined with some of the firm’s other products, capabilities, and technologies. Honeywell will also package pressure and thermal sensors to facilitate easy customer implementation. .
Honeywell offers the following:
A supplier who can improve time to market by reducing production cycle time by providing the sensor interface as well as ease in manufacturing by providing a plug and play assembly. Honeywell also provides a tested and warranted sub-assembly, which improves reliability by reducing failure points. The product is optimized because the solution utilizes 6 Sigma and lean processes. Qualification and manufacturing is simplified due to having a single part number for purchasing, engineering, manufacturing and tracking.
In medical applications there are three critical factors for choosing force and pressure sensors for use in infusion pumps: reliability, sensitivity, and miniaturization. As infusion pumps transition from bulky models to portable, ambulatory, and implantable devices, designers should consider sensor platforms that provide a range of options that make them easy to implement in a variety of designs.
Designers should also consider pressure sensors that are fully compensated, amplified, and calibrated. The benefits include lower total costs, higher reliability, and faster speed to market.
Force and pressure sensors must provide high reliability and high sensitivity to ensure the desired amount of medication is being delivered to the patient. Board-mount pressure sensors are used inside the pump to monitor and help control the flow of fluid. Force sensors on the outside of the pump measure force non-invasively on the outside of the tubing that delivers the medication. Measuring the force on the outside of the tubing eliminates the requirement to sterilize the sensor. Force sensors can detect if there are any blockages in the pump’s tubing and signal an audible alarm if the medication is not being delivered.