Can Integrate a Gauge Pressure Sensor Into Circuit?

Board level sensors are ideal for integrating onto a PCB, but they’re typically limited in the temperature range they support. You will also find that they’re not suited for monitoring most liquids and chemicals.

Industrial gauge pressure sensors are an ideal alternative. They’re typically housed in a robust metal case, making them suitable for use in damp and corrosive environments. They also feature a screw thread, allowing them to be fixed to tanks and pipes with ease.

When developing firmware to read the pressure provided, note should also be taken of the warm up time of the sensor. After initial power on, it may take several milliseconds before the output can be relied upon.

If the sensor is part of a control loop, the response time for the sensor should also be reviewed. Gauge pressure sensors’ response times are often specified by the time taken for the output to change from 10% to 90% for a step change in pressure.

Sensors with a digital output tend to support the I2C or SPI protocol. However, there are exceptions. This is typically not native to micro controllers, so supporting this interface in firmware will require some significant programming effort, as well as demanding a lot of processing time.

However, one of the challenges you may face is interfacing them to your system, especially a micro controller. Industrial complexes are often required to fulfill high levels of safety to protect their workers from the high pressures, corrosive liquids and dangerous equipment in their environment. Industrial gauge sensors are therefore designed with interfaces that are intended to guarantee that the measurements they deliver are always reliable.

Many “transmitter” type sensors encode their output as an analog signal in the form of a current between 4 and 20 mA. This can be in the form of a two-wire interface that doubles as the power supply to the sensor. This would need to be replicated in your circuitry as shown in the diagram below.

An example circuit showing how a gauge sensor transmitter may be implemented

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