Suckback in cracking


Hi, can someone explain how suck-back happens in cracking?

In: Physics


Temperature changes cause pressure changes. You heat up your component to crack it, and as the collection tube cools the pressure change from the temperature change can cause fluid to be sucjed into the collection tube.

After removing the heat source under the test tube, the tube cools down, thus decreasing the pressure in the heated tube. If you don’t remove the delivery tube before removing the flame, water from the collection tube (of higher pressure) will rush to the heated tube (of lower pressure), cooling the heated tube down rapidly and causing it to shatter.