I bought one used,its a saviair 5000 and original price is ridiculous $4000.they are on ebay or similar sites for $3-400.It does help they ony time you get a spark is if it picks up s large dust particle,as far as blowing up the insurance companys make manufactuers the warning on anything,oxygen only enhabses a flame,you would have to have a huge consentration in a small room for anything to blow up,the oxygen warning is mostly for the tanks,if there is a fire when heated up the tanks can blow up,but otherwise a concentrator is quite safe.

when buying your air purifirer I would ask that question befor I buy it I dont know that question for sure,I use mine in the day time only.

Thanks

had mine a long time,it does not have a filter work good dont remmber where I brought it.

If you do get one let me know how it worked out, Thanks