Solvent-type liquid ring pump
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This post was last edited by suhuoyi212 on 2019-10-28 at 13:27. I would like to ask whether it is possible to use a solvent instead of water as the liquid ring in a vacuum pump. Could there be issues with explosion protection? When performing distillation, I’m not concerned about the oxygen level in the system. I’m very worried that when vacuuming begins, the oxygen in the system might combine with the solvent in the liquid to create an explosive atmosphere. Such pumps are available on the market currently, but it is unknown what their safety level is. If this pump is rated for Zone 1 explosion protection, I’m not sure if it can be used.
The system can first be purged with nitrogen to remove the oxygen from it, and then a vacuum pump can be used to create a vacuum, thereby preventing the formation of conditions that could lead to an explosion
The use of solvents in liquid ring pumps has nothing to do with the fact that the pump is rated for Zone 1 explosion protection; one aspect relates to electricity, while the other relates to the pump chamber – they are not in the same area； It is possible to use a solvent; one can first displace the air with nitrogen, but attention should be paid to the saturated vapor pressure of the solvent.
The operational safety of solvent-based liquid ring pumps cannot be ensured merely by meeting the requirements for Zone 1 explosion protection; it is also necessary to take into account the properties of the solvents used. For example, if the vapor pressure of the solvent at the pump’s outlet temperature, expressed as a volume percentage, is close to or even exceeds the lower explosive limit (taking into account any small amounts of volatile flammable components present in the system as well), then there is a significant safety risk and such pumps are not suitable for use. Because, since vacuuming is being performed, what is mainly removed is the air that has leaked into the system as well as a small amount of volatile components; it is therefore necessary to take care to prevent solvent components and volatile flammable components from forming explosive mixtures with air.
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It’s not only motors that have explosion-proof ratings; mechanical equipment as well does. The OP is right to consider the risks