Misunderstanding of the Glove Box: The Chamber is Positive, The Air does not Leak in the Glove Box?

The movement of the gas is from a variety of forms such as flow and diffusion, and the flow is a pressure-driven region, i.e., the gas flows from the high pressure region to the low pressure zone, and the diffusion is a concentration drive, i.e., the gas molecule is moved from a high concentration region to the low concentration region. Therefore, in a macro, the gas always flows from a system of high pressure to a system of low pressure.

For the glove box, if the seal of the chamber is from a larger gap (such as> 0.1 mm), when the pressure in the glove box is greater than the pressure outside the glove box, the gas in the chamber flows faster to the glove box faster.

However, when the gap is small (such as <0.001mm), the fluid resistance is very large, and only a few mbar of the glove box (one thousandth atmosphere), the flow rate is very slow. The concentration difference of the internal and outer oxygen in the glove box is 200,000 times, and the oxygen in the air can diffuse into the chamber from the tank through these micro gaps. At the same time, nitrogen in the glove box diffuses from the chamber. Although the air pressure in the glove box varies greatly, the concentration of oxygen has increased a lot.