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Name: Grant L.
Status: Other
Age: 30s
Location: N/A
Country: N/A
Date: N/A


Question:
Pure Nitrogen gas is used for energy storage in hydraulic accmulators. Some large, low pressure accmumlators have no membrane to separate the oil and nitrogen. The nitrogen eventually gets disolved/diffused into the oil and periodically needs to be recharged.

Question:
Does the nitrogen dissolve faster at higher pressures?
How deep into the oil will the nitrogen penetrate?



Replies:
The general rule is: Gases become more soluble in a solvent when the pressure increases. This is expressed quantitatively by Henry's law that states that the pressure is proportional to the concentration of the dissolved gas -- P = k*C, where P is the gas pressure, k is an empirical constant, and C is the concentration of the dissolved gas (all quantities being in a consistent set of units. The "bends" suffered by deep sea divers is a consequence of the same trend in the solubility of nitrogen in blood.

As an aside, the solubility of gases to my knowledge, decreases with increasing temperature.

Vince Calder



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