Gas extraction from the ball bladder Yang

There is a problem with the sampling technique: even if gas remains in the inner bladder each time you take a sample, air still gets in. After each replacement, hold the air inlet of the bladder with your hand; do not take samples with it left open.

Regarding this sampling issue, I watched a video online yesterday that showed how to take samples using aluminum foil bags; the replacement process involved rolling up those aluminum foil bags. I’m not sure if rolling up the bags can be used for replacing balloon tanks as well. I’ll give it a try when I get to work today

We have been using bladder samples; just pay attention to that.

Personally, I think aluminum foil bags are more convenient; replacing them multiple times (10 times or more) may reduce errors

How do you replace the ball bladder to prevent air from getting in?

If nitrogen and oxygen are analyzed separately, and the components being analyzed are not affected by nitrogen or oxygen, it is fine to have a small amount of air enter; in the analysis results, an adjustment can be made by accounting for the nitrogen-oxygen ratio in the air. If sampling with soft materials is inconvenient, a stainless steel sampling bottle can be considered, along with a gas injection valve for sampling in order to avoid the influence of air.

We will perform the replacement two to three times; those on the fourth floor, please pay attention.

I don’t know what type of gas sample you collected; I used a balloon to collect blast furnace gas and coking gas as well. During sampling, air was introduced and then expelled, the outlet was blocked after expulsion, and then air was introduced again and expelled, repeating this process 3-4 times. After sampling, it was sealed with a hemostatic clip. During operation, if sampling is done improperly and exhaust replacement is not thorough, oxygen levels may rise above the acceptable limit, which causes tension throughout the gas station, prompting further sampling and testing.

The methods for sampling various gases in chemical production are the same; generally, during system startup and shutdown, the oxygen content is kept below 0.5%, and it remains very low during normal operation. The sampling error is greater than the analysis error; it’s not easy to clarify this sampling issue right away – by trying to take samples more often, one will gradually understand it.

The situation mentioned by the original poster is caused by air being accidentally introduced during sampling. When replacing the bladder by sampling, some say it is necessary to squeeze out all the air to ensure a complete replacement, while others suggest leaving a small amount of gas to prevent the bladder from contracting back after the air is removed and absorbing more air. So, neither of these two statements is wrong in itself. When replacing the balloon with sample gas, coordinate the use of the left and right hands; after each expulsion of gas, hold tightly the rubber mouthpiece of the balloon with the right hand, keeping it pressed down. Open the sampling valve, aim the sample gas at the rubber nozzle of the sampling valve and blow for a few seconds, then release your finger. This way, a small amount of air from the rubber tube opening will not be drawn into the ball bladder. It’s explained in some detail; I’m not sure if the original poster will understand. Practice more*; once the techniques are mastered, generally three to four sampling and replacement sessions will be sufficient to meet the requirements.