A pressure transducer is a device that directly measures the force of fluid or gas and converts the value into an electrical signal. The unit typically includes a diaphragm that responds to pressure changes, which pushes or pulls on a component called a strain gauge. Electrical resistance is created which is generally representative of the pressure. There are generally three types of electrical output for a pressure transducer: millivolt, voltage, and 4-20 milliampere output. Sensors are often available in a variety of styles and can connect to processors, controllers, and computers by using an analog-to-digital converter.
The electrical output of a pressure transducer generally determines what environment the product is suited for. With a millivolt output pressure sensor, the output is completely dependent on the input power level, so fluctuations in electricity can affect the reading. Voltage output sensors have a higher output that is not directly impacted by the input power, and can be used in industrial facilities where electrical currents can often stray.
Another kind of pressure transducer is a 4-20 millampere sensor. Electrical noise doesn’t usually affect this type as much as the others, and it can sometimes transmit signals to more than 1,000 feet (more than 308.4 meters) away. All types of pressure transducer can be characterized by their range, or the lowest and highest pressures that can be measured accurately. They can also be identified by how far over the pressure range normal operation is possible. Resolution, or how small a pressure change can be detected relative to total capacity, is often another consideration.
A pressure transducer can be affected by temperature as well as Electromagnetic Interference (EMI). These can affect the output, while some transducers are shielded and grounded against EMI up to certain intensities. Materials used in the sensors such as stainless steel, plastic, silicon, or epoxies can be adversely affected by certain pressurized fluids.
Some pressure transducers can be mounted to a computer board and typically come with contacts for a solid connection. Others, specifically designed for industrial environments, often feature a thick, strong enclosure. General purpose devices usually have a standard design that allows them to be connected to commonly used equipment. Often more expensive than other varieties, a high-accuracy pressure transducer generally has very low errors, expressed as a percentage of total capacity. A different type of pressure sensor can eliminate the risk of thick fluids building up between the diaphragm and other components.
By Andrew Kirmayer