Why is nitrogen used instead of air for the airtightness test of low-pressure systems? ? ?
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Why is nitrogen used instead of air or other gases for the airtightness test of low-pressure systems? ? ? Are there any risks? ? ?
Because even after making the relevant system airtight, it still needs to be purged with nitrogen.
After completing the airtightness test and carrying out the water testing, isn’t it still necessary to use nitrogen for drying and purging?
Because in some areas, if the replacement is not thorough, the moisture in the air can easily freeze at low temperatures
Since compressed air contains a certain amount of moisture, if it is not properly treated, it can affect the operation of the system. There is a certain degree of risk. Some devices prohibit the presence of water vapor, and hot nitrogen is used for purging.
This mainly depends on the availability of facilities throughout the plant; if nitrogen is available, then it will definitely be used； If nitrogen has not been produced by air separation, then compressed air can only be used ； Compressed air is also acceptable; airtightness testing involves checking for tightness and strength, and there are also tests related to water operation and drying. Whether compressed air contains water or not is not important.
This post was last edited by ningzi521 on 2015-12-14 at 10:18. If nitrogen is available, it should still be used; after the airtightness test, nitrogen is needed again for purging before starting up the system with water. Using nitrogen for airtightness testing helps save time, as plants in chemical factories need to get operational as quickly as possible. Air tightness is also acceptable; it at least provides some level of protection for the safety of personnel during leak detection.
Air contains oxygen, which can oxidize equipment. Even waste materials left over from construction processes, such as iron shavings, gloves, plastic and other flammable substances, can generate sparks or even cause fires when they come into intense friction within pipes in an air-filled environment
It seems reasonable, but in fact it is not. Using air for airtight sealing is a normal practice, and it is superior to nitrogen in some aspects.
Nitrogen must still be used for drying and purging.