Pressure sensors/transducers/transmitters are offered with a wide variety of pressure ranges, configurable options, sizes and approvals. This can make selecting the proper pressure sensor for your application difficult. The following are the key features of a pressure sensor design/construction that need to be considered to help narrow down selection and ensure the most appropriate sensor is selected:
The mechanical interface, also referred to as the process connection, is how the sensor is connected to the pressure source. This is typically done via a threaded connection. There are a wide range of thread types including NPT, SAE/UNF, BSP, DIN, Metric and even TUBE STUB. Male and female versions are also available. Certain factors may limit the availability of the process connections including wetted material requirements and pressure range. Custom connection options are available upon request.
Pressure Sensors are available in pressure ranges from SUB 1 PSI up to 50,000 PSI +. Compound (i.e. -14.7 to 100 PSI) and bi-directional (i.e. -10 to +10 PSI) pressure ranges are offered for applications such as water pumps to measure suction and discharge and vapor recovery in landfills. It is also important to note if your application will produce sudden pressure spikes (known as water hammer). These spikes are common in hydraulic applications such as a forklift suddenly dropping its load to the ground and a fast closing valve while fluid is still flowing. These pressure spikes can surpass the operating pressure of the sensors internal sensing element and, at a minimum, can cause permanent shifts in the sensor’s output.
The electrical interface, also referred to as the electrical connection, is how the output signal is transmitted to a PLC or other data collection instrument or display. Electrical connection options include integral cable, connector or inline connector. Customers can choose from connectors such as DIN 43650-A and C, M12x1, Packard Metripack 150, 6-Pin Bendix, Deutsch DT04 3 Pin and 4 Pin as well as many others. Some pressure sensors have a limited selection of options due to hazardous certifications and design limitations. Custom configurations are available upon request.
The environment where the sensor will be installed should be considered. Different connection types offer different ingress protection (IP) ratings. Sentech Sensor Engineers can help guide you on the best electrical interface based on your installation environment.
Power Supply/Output Signal:
The available power supply, sometimes referred to as the Excitation or Supply Voltage (or Current), is an important consideration. Pressure Sensors can be supplied that will operate from voltages as low as +3 VDC for remote telemetry battery operated applications all the way up to +32 VDC. Determining the available power supply will help determine the output signal options. For long distance signal transmission, a 4-20mA output signal which can operate off of an unregulated 10-28VDC excitation voltage is suggested. High level voltage output signals are also available which offer low current consumption. These voltage output signals are not recommended for transmission over 20 feet. There are multiple voltage signals available requiring different power supplies. For example, a 1-5V output signal requires a 10-28VDC unregulated power supply while a 0.5-4.5V ratiometric output signal requires a regulated + 5VDC power supply. Digital interfaces such as I2C are also available.
The process media is the gas/liquid in the application whose pressure is being measured. Understanding the process media will help guide the selection of the mechanical interface material (wetted materials). Common material choices include stainless steel (17-4PH or 316L), exotic alloys (Hastelloy C276 and Inconel 718), and Titanium Alloys.
Understanding any approvals/certifications that are required in your installation will help guide you to the appropriate pressure sensor product family. Most sensors currently offer CE marking. CSA and FM certifications for Class 1, Div 1 Intrinsically Safe and Explosion Proof installations is also available.
Identifying your requirements and preferences will greatly simplify the process of selecting the most suitable pressure sensor for your application. Call us today at (858) 336-1144 to discuss your application with a knowledgeable Sentech Sensor Engineer.