Freezing inside the pressure tap tube
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Dear seniors: I would like to ask what the pressure is approximately when water in an 18-mm stainless steel pipe about one meter long freezes at -5°C? Furthermore, with the same installation method, the diaphragms of Yokogawa’s pressure transmitters are fine – so why did those of Rosemount get damaged due to freezing (5 units were damaged in just one night)?
Liquids are incompressible; freezing is a process of volume expansion. It is necessary to understand this freezing process, as well as how much water is expelled during it.
There’s a lot of pressure! If there’s too much water, pipe freezing and cracking won’t be a problem! There are many ways for pressure tap pipes to freeze! Different parts of the body being affected by the cold, and to varying degrees, result in different outcomes! Rosemount products are similar to EJA products! Also, check whether the diaphragm type of your transmitters is the same! When water in the diaphragm box freezes into ice, it first causes the diaphragm box to deform due to freezing! Make it change linearly! If it can recover on its own, the gauge can still be used! But it might be necessary to downgrade for use! Severe freezing can crack the silicone oil inside the diaphragm box! It causes the diaphragm box to lose its elasticity! The diaphragm box of the table is completely damaged! The screw mount diaphragm issue will display a \"no p\" message!
The expansion force when water freezes is very large; it can even crack steel pipes, let alone the diaphragm boxes of transmitters.
All of them are NO P, but those from Yokogawa work fine; I’m not sure what’s different about their internal structure
Rosemount’s diaphragm is capacitive, while EJA’s is resonant
You need to check whether it has a single cartridge or two cartridges! Is it low pressure or high pressure! They’re all different! It is still recommended to change the pressure tapping method! Ensure proper insulation and heating! Solve this problem completely!
I know how to solve problems； I’m measuring the steam pressure; under normal conditions it’s around 800 Kpa. The pressure rating of the Rosemount pressure transmitter I’ve chosen is G2 ； I want to know: 1: What can be the maximum pressure at the time of freezing? 2: With the same installation method, why is Yokogawa not having any problems? Thank you!
What is the difference between these two? I searched on Baidu but didn’t understand it; thanks!
When water freezes, its volume expands by about one-tenth; a 1-meter long pipe will become approximately 10 cm longer. Moreover, the pressure is very high once freezing occurs. Here, we have examples of cable trays that were filled with water, and the freezing caused the cables to bend
Pipes can even freeze and crack! This natural force cannot be measured by pressure! You have to check the degree to which each surface is frozen! The degree of freezing at the diaphragm box! If measuring steam, then using antifreeze as the condensate works very well! I don’t know the models of the two tables you’re talking about! The structural design of the diaphragm box! Perhaps the diaphragm chamber of the eja is larger, with more space! So the impact is smaller! If the degree of freezing is the same, then it depends on the structural format of each table!