The compact analogue rod-type pressure transmitter and the Process SMART pressure transmitter are all used to measure pressure.
Although the purpose of using these devices is almost identical, their technical specifications vary greatly between these different types, resulting in many aspects such as the accuracy or resolution of the measurement.
Once these details are clearly defined, it will be clear which instrument is most suitable.
This article looks in detail at each of these types, and their advantages and limitations, to help you make the right choice.
A compact pressure transmitter uses different technologies including piezoresistive pressure transmitter, thick film ceramic pressure transmitter, thin film metal pressure transmitter.
These sensors convert a physical pressure measurement into an analogue electronic signal.
The transmitter signal output is usually in the form of voltage (0 to 5Vdc ; 0 to 10Vdc) or current (4 to 20 mA).
There are several pros to using a compact pressure transmitter over a process pressure transmitter.
First, the compact analog pressure transmitter is typically less expensive than the process pressure transmitter.
Second, the compact analog pressure transmitter is smaller and lighter in weight than the process pressure transmitter, making it easy to install in confined spaces like machines.
They are commonly used for aerospace, automotive, industrial equipment, and medical applications.
However, there are a few cons to using a compact pressure transmitter.
The compact analog pressure transmitter has a fixed range compared to the smart pressure transmitter. The range cannot be set by the user.
The signal from the compact analog pressure transmitter is always noisier than the signal from the smart pressure transmitter.
The compact analog pressure transmitter does not offer linearization or temperature compensation.
The compact analog pressure transmitter is less accurate than the process pressure transmitter.
Without the temperature compensation, the zero point of the compact analog pressure transmitter shifts when the ambient and the process temperature change.
Additionally, compact analog pressure transmitter are more sensitive to environmental conditions and can be more prone to failure than smart pressure transmitters.
Any transmitters drift over the time. In order to get good accuracy, the sensors need to be calibrated regularly.
The cheapest compact analog pressure transmitter because of their design compared to high-class pressure transmitters are suggested to more drift.
The compact analog pressure transmitter require more regular calibration and more maintenance.
Smart pressure transmitters are an upgraded class of pressure transmitter that linearize, amplify, and compensate pressure measurements before displaying the reading.
Smart pressure transmitters are able to perform pressure monitoring and control applications, therefore making them an integral part of fluid power systems.
The transmitter signal output is usually in the form of current (4 to 20 mA) with digital communication protocol (HART, Modbus, Profibus).
There are many advantages to using a Smart pressure transmitters over a analog pressure transmitter :
The Smart pressure transmitters thanks to the linearization of the pressure measurement is more accurate and reliable than compact pressure transmitters.
The Smart pressure transmitters' accuracy is 0.065% or better of the set span.
The smart pressure transmitters are compensated against ambient and process temperature variations.
That makes them independent of external environmental conditions.
Smart pressure transmitters can be calibrated with tools by using the HART protocol to compensate for the drift over time and ensure long-time stability.
The range of the smart pressure transmitters can be calibrated on-demand to the exact span required for the application.
They can be set through a wider range of pressure.
They have a pressure range turndown ratio that permits changing their current setting over a large range.
The process pressure transmitters have a longer life span and are more durable than compact pressure transmitters.
A large choice of material and process connection is available.
Their construction is robust thanks to their design that includes high-quality steel material, TIG welds, high-grade bolts and nuts, superior gaskets and seals.
They are vibration-resistant and have high Ingress Protection for strong protection against dust and humidity.
They can be used for high-temperature applications with diaphragm seals.
There are several disadvantages to using a smart pressure transmitter over a compact pressure transmitter.
Smart pressure transmitters are more expensive than compact rod type pressure transmitters, so there is a trade-off between cost and performance.
Their size and weight are bigger than the compact rod type pressure transmitters.
So, they cannot be installed in the application for which these parameters are paramount.
A pressure sensor can be used for many different applications in manufacturing and industry, which one should you choose for your application?
There are different things to consider when deciding on what type of sensor would work best for your project: pressure range, accuracy, performance, output signal, process temperature, nature of the fluid, and the price range
The compact pressure transdmitter offers a fixed pressure range.
On the other side, the smart pressure transmitter's range can be tailored to the application for a perfect match.
Process pressure transmitter accuracy is 0.065% or better of the set span whereas low cost pressure transmitter accuracy is 0.25% of the full range.
The smart pressure transmitter thermal performance and long-term stability are 50 times better than with compact pressure transmitter.
The smart pressure transmitter's analog output signal is 4-20mA with HART protocol whereas the compact pressure transmitter analog output signal is 4-20mA or 0-10V without HART protocol.
The low cost pressure transmitter temperature is limited to 100°C whereas the process pressure transmitters thanks to the diaphragm seal can withstand temperatures up to 450°C.
Hart protocol allows setting the parameters of the smart pressure transmitters.
They can also be used for self-diagnosis to control the transmitters' health over their lifetime.
This communication protocol is not available on low cost pressure transmitters.
The process pressure transmitters are available with a large choice of material and construction which makes them more versatile and robust compared to the compact pressure transmitters.
The price of the process pressure transmitters is in the 400-600 euros price range whereas the low cost pressure transmitter's price is around 100-150 euros.
This article explains the main difference between a compact analogue rod-type pressure transmitter and the Process SMART pressure transmitter.
It's written to clear up any misconceptions about the differences between different sensor types and to help you select the most appropriate one for your application.
Low cost pressure transmitters are less expensive than process pressure transmitters, but they also offer fewer features and lower accuracy.
They can be chosen when you don't need high accuracy and when you are not strict about the performance and the measurement drift.
They are economical and satisfactory for applications with standard pressure ranges and process connections.
Compact pressure transmitters are typically used in lower-end applications where cost is a major consideration.
When comparing the price of a compact pressure transmitter over a smart pressure transmitter it is essential that you consider the Total Cost of Ownership.
Due to its long-term stability and robustness, the process pressure transmitter offers low maintenance costs and higher equipment availability than the low cost pressure transmitter, making it cheaper and safer in the long run.
Smart pressure transmitters offer more features and higher accuracy.
They are a better choice for more demanding applications like in oil&gas, pulp&paper, chemical, hydrogen, power, metal and cement industries.
Contact an expert in pressure measurement, by email or phone.