Discussion on technical issues of online density meters

At a temperature of 100 degrees, and in the presence of corrosive substances such as acetic acid and chloroacetic acid, which type of online density meter is suitable?

First, it is necessary to determine whether the medium being measured contains bubbles. Additionally, chloroacetic acid is quite corrosive; therefore, the material used for the sensor should be corrosion-resistant. If bubbles can be easily dealt with at the site, the pipelines there can be modified, and an ultrasonic density meter could be considered. Since the temperature reaches 100 degrees Celsius, a differential pressure type meter is not recommended. If cost is not a concern, a mass flow meter is advisable. As it needs to be corrosion-resistant, it’s best to use imported meters, or domestic meters that meet the corrosion resistance requirements! I would also like to specifically ask about the manufacturing process: whether bubbles are present. I have worked on similar designs before, and bubbles do form; it’s important to determine exactly how many bubbles there are, as this can affect the measurement results. From what I’ve seen with density meters, straight-tube density meters give much better results when measuring materials containing bubbles, while curved-tube density meters require stricter standards regarding the presence of bubbles. This is just my personal opinion, for reference only

May I ask the original poster, what type of online density meter is suitable for measuring the calcium chloride density in the main pipeline leaving the workshop and in the chilled water tank? Thank you

Thank you for the help. Will the lifespan of the quality densitometer be affected at 100 degrees? Can Hastelloy C used for the measurement tube meet the requirements for this medium?

This should relate to the technology used in central air conditioning systems. From what I understand, some places use differential pressure methods for this purpose, but the results are not good. The main issues with this approach are low temperatures, as well as the formation of bubbles when the liquid is exposed to changes in temperature. This poses significant challenges when selecting sensors. Additionally, calcium chloride solutions are corrosive. The best solution is to use a straight-tube type density meter; mass flow meters aren’t suitable for this purpose. Bent-tube type meters don’t work well either due to the presence of bubbles. In my opinion, the best options are straight-tube mass flow meters or straight-tube density meters. There are already manufacturers in China that produce such devices. I hope this helps you; feel free to leave a message if you have any further questions. As for why differential pressure methods don’t work, I won’t go into detail – they simply aren’t suitable for this application. If they must be used, it’s very complicated, requiring process modifications. I’ve designed systems using these methods before, and it’s not convenient at all

Firstly, the temperature is indeed a bit high. However, it’s not the high temperature per se that shortens the lifespan of the mass flow meter; rather, it’s the concentration of the medium being measured, along with the 100 degrees Celsius temperature, that together increase corrosion. If the concentration isn’t too high, Hastelloy can be used. Additionally, the wall thickness of the straight-tube type mass flow meters is relatively thin, which can lead to corrosion of the sensor. It would be best to reduce the temperature. High temperatures cause stronger molecular ionization, resulting in the formation of salts and acids from hydrogen ions and chloride ions. When the concentration is high and the temperature is also high, the corrosive effect of these salts and acids is quite strong; but if the concentration is low, Hastelloy can still be an appropriate choice. I also suggest considering whether it’s possible to lower the temperature within the constraints of the manufacturing process. This is just for reference – feel free to message me if you have any questions

Thank you, OP. I wonder if the original poster has used ultrasonic ones; I’m curious to know how effective they are

Regarding sensors, no separate explanation will be given for any individual product, as sensors based on different principles are all designed to carry out indirect measurements; each of them has its advantages and disadvantages! No comments will be given here; it’s just a technical exchange!

Currently, the domestic ultrasonic devices are not up to standard; moreover, starch paste has a strong tendency to form scale, which requires additional analysis. The choice of sensor depends on an analysis of the sensor’s principles and manufacturing process; no conclusion can be drawn solely based on that. It’s not meant to disparage other brands, but ultrasonic sensors indeed are not suitable

Under no circumstances use ultrasonic devices – those available in China don’t work; they’re a scam. It’s not that certain ones are bad, but they truly don’t function. The reasons can’t be explained in just a few words, and you’ll definitely regret using them!