Hi Guys

Today i was reclaiming gas out of a domestic unit it works fine. but no need for it any more and also another condensing unit which boss said was working fine.
In both the cases after when i reclaimed the gas and before i disconnect hoses or purging wait to see on the manifolds of any pressure rise, all of a sudden heard a bang noise out of compressor of the fridge and the condensing unit.
and then the pressure rise on the gauges.
I was wondering what that noise was perhaps the refrigerant trapped under the oil but not sure.

Thanks Guys