Is an instrument protection box still necessary?
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Is it still necessary to have an instrument protection box/insulation box for the transmitter? Today, transmitters have a fairly wide range of operating temperatures, and can generally function within the range of -40 to 80 degrees Celsius. In other words, the transmitter can operate properly within this temperature range. Moreover, the protection rating of these transmitters is above IP65, so they can operate outdoors for extended periods without any issues. So, are instrument protection boxes/insulation boxes still necessary? If it is merely for the heat tracing of the pressure guide tube, then it should be sufficient to carry out heat tracing and insulation work on that tube alone.
During process maintenance, when valves, pipes, and equipment were installed, they accidentally hit the transmitter; it’s not clear whether the transmitter will remain unharmed
This post was last edited by Shutong on 2022-12-31 08:50. Let me share my opinion; I’m an amateur after all. When installing transmitters for pressure, flow rate, etc., on-site, instrument protection boxes are often used to prevent freezing and maintain temperature stability, and they also serve to protect against dust and rain. The box should be splash-proof, dust-proof, and corrosion-resistant, and it must provide sufficient working space for maintenance. It should have large enough doors in a suitable location to allow for the replacement of instruments. The pipeline should enter from the bottom or side, and it must be properly sealed; windows should be installed where necessary. Please refer to: Automation Instruments in Production Processes: Reading and Installation, 2nd Edition, edited by Li Ji, published in 2011, Chapter 9, page 221, for information on instrument protection; please visit the Shutong Database for such materials
The instrument protection box (insulation box) not only protects the instruments but also safeguards the media that enter them from environmental influences. For example: when the ambient temperature drops below 0°C and the water in the transmitter’s measurement chamber freezes, it can no longer perform accurate measurements ； Moreover, the mechanical damage caused by freezing expansion is also outside the operating conditions permitted for the transmitter. .
That makes sense. That is, the protection box can prevent damage from external impacts.
Is it possible to use a certain installation method to retain any mist that may form in the pressure guide tube within the process pipeline?
In areas where environmental and climatic conditions are tolerable, if the enclosure of the field instrument meets IP65 or even a higher standard, is made of metal, and the display content does not need to be viewed even under slightly unfavorable conditions, it is not necessary to use an instrument protection box. Some two-wire instruments, due to limitations in power supply and power, are unable to display properly when the temperature is too low or too high; however, this generally does not affect the output of the measurement values. However, China has a vast territory with diverse climate conditions, and factory environments can also be quite complex; in such cases, I think it is necessary to install instrument protection boxes.
The analysis is very thorough; using a protection box is definitely the right choice, it just means an additional cost. What about some applications suitable for end-mounted use? For example, in the case of pipes with a platform outdoors, a pressure transmitter can be installed directly above the pipe; in such a situation, there is no need to add an additional protection box, right?
Being able to operate at low temperatures and having to operate at low temperatures are not the same thing; extreme operating conditions will certainly affect the lifespan of the transmitter.
On-site piping installation or on-site bracket installation is already limited by the conditions at the site; adding a protective box seems unnecessary. For better visibility, it’s better to omit the protective box. If the display isn’t clear enough, it’s quite necessary to install an on-site display panel that makes it easy to read the values.
When the factory was built, I installed protection boxes for everything; they were made of fiberglass. After a few years of use, they deteriorated, and now some of them have been replaced with stainless steel ones, while others are installed directly on the equipment itself, without any protection boxes anymore.