How to choose a good pressure transmitter?
A variety of potential applications and installation locations for pressure measurement means that each of the rules must be set quickly and easily. These tips are really some basic guidelines for better selection of pressure measuring device for You are recommended.
1. Transducer or transmitter?
The first step is to choose the transducer or transmitter. Although terms are often confused, there are several differences between transducers and transmitters. A transducer generates a low-level electrical signal in response to pressure changes or pressure differences. Like transmitters, transducers have an internal sensor that converts the applied force into an electrical signal from which pressure can be measured.
Transducers are usually suitable for harsh environments and are not suitable for many industrial applications. The body of transducers is usually small and can not easily be connected to standard industrial piping. Compared to transmitters designed for industrial use, most pressure transducers are suitable for laboratory use.
Transducers have disadvantages that are generally unsuitable for widespread use in industrial environments. They are generally suitable for highly probable environments where there is no risk of water and dust penetration. They are also weak against the effects of pressure concentrations or damage caused by sudden changes in process conditions.
Most importantly, the transducers do not have enough energy to send the signal as far as the transmitters can. There is also a wide range of certified temperature transmitters available for use in hazardous areas and areas with high temperature and humidity.
Compared to transmitters, most converters also offer a limited amount of tuning and have lower stability and lower measurement accuracy. They offer limited compensation for changes in process or environmental conditions such as temperature, and are often fixed range devices that can only measure in a given area.
Transmitters have two basic components for measuring pressure or pressure difference. A primary element (pressure sensor) is directly or indirectly in contact with the measurement process, while a secondary electronic package transmits the measurement from the main element (pressure sensor) to a signal that can Data through a fieldbus protocol such as the Foundation Fieldbus or Profibus or an output signal standard of 4 to 20 mA dc. Transfer.
This secondary electronics is very complex and performs many functions that transducers are unable to perform. For example, process differences or environmental conditions measured by the primary sensor can be compensated automatically before it becomes a 4 to 20 mA signal. Other functions include square for flow applications, totalizers, and reverse current output performance.
These transmitters reduce unwanted measurement errors and keep the transmitter very stable in the output signal. Operators can also calibrate the transmitter over a wide range of inlet pressures, and one unit can be used to measure a wide range of readings.
Consider your operating environment
Modern pressure transmitters should be able to operate easily in low temperature, humidity and vibration conditions, if they are within the design specifications. Minimizing the effects of such conditions will help increase the operating life of the transmitter.
Most electronic transmitters are suitable for ambient conditions, ranging from a low of -20 ° C to -40 ° C and a high of 60 ° C to 85 ° C, although this may not be the case for some special cases.
Environmental conditions can significantly affect the accuracy of the transmitter. This can be not only the inherent background temperature of the installation site, but also the heat generated by a process or the radiation from the surrounding process equipment and piping.
High temperatures can cause damage, which potentially causes the component to break prematurely. Over device parameters can have a significant impact on performance. For example, low temperatures can cause liquids to become more sticky, while high temperatures can cause them to evaporate. Changes in ambient temperature and pressure can also affect.
Vapors from wet conditions can sometimes penetrate the pressure transmitter area and penetrate sensitive components. Also in contact with high humidity can cause corrosion of the transmitter housing and its bases.
Pressure transmitter housings are designed to protect electrical components from moisture ingress. However, it can be problematic even if the cover of the enclosures is threatened during commissioning, operation or repair.
Avoid installing a transmitter in the desired area to a long or unnecessary level of vibration, as this can reduce the useful life of the transmitter. To protect against potential damage or malfunction due to vibration, the transmitters should be located in a location that is not exposed to vibration during operation.
5. Two wires, digital or wireless?
There are different types of transmitters, each of which uses different techniques to transmit the signal. The transmitter’s role is to amplify and modify the signal so that it can reach long distances to the control room or local devices such as indicators, recorders, and controllers without interruption or interference.
For most applications where power is readily available, a two-wire transmitter that uses 4 to 20 mA of both current to operate the circuit and send a signal is often the most practical choice. As current is protected against the effects of resistance changes along the line, signals can be relayed over long distances.
Where accurate data transmission or large amounts of information (such as diagnostic information) are necessary, digital transmitters may be the best choice. Digital signal transmission allows a large amount of information to be transmitted between the device and the control room. Fieldbus technologies such as Foundation Fieldbus, Profibus PA (for process automation) and DP (for discrete or factory automation) allow data to be quickly transferred to the control room, where it can be applied through the control system. Make informed and prompt management decisions.
Where fast data transfer is less important, a WirelessHART device may be a good solution.
WirelessHART offers the perfect solution for any application where it is economical or impractical to have a wired device. The ability to remotely analyze the wireless device up to 200 meters also eliminates the need for operators and maintenance staff to visit unsafe areas such as high altitude in the column.
With the cost of wiring and installation accounting for almost 50 percent of the total cost of the device, both financially and technologically there is room for wireless devices to be used wherever possible. Wireless devices are mostly limited to recessed applications in remote installations, such as water distribution or oil and gas. However, the introduction of the WirelessHART protocol means that the industry now has an international standard that enables wireless devices to communicate a variety of information across factory networks.
Reliability is key, and the WirelessHART network architecture is a rugged solution that can create information to bypass incomplete nodes and provide secure service.
Rose Calibration Company in Melbourne, Australia with over ten years of experience provides all calibration, maintenance, and repair services throughout Australia. If you live in Sydney, Melbourne, Adelaide, Perth, Geelong, and Brisbane, you can receive your quote in less than two hours by fill-up the form via the “Booking” link.