Most air separators are designed for, and are capable of, running 24/7 for years.
In normal duty an air separator will run for a large portion to the day (at least half ). Part of the standard manufactures warranty for NEW air separators includes any needed repairs up to 30,000 hours. Assuming 30,000 hours is a reasonable trouble free lifespan this equates to almost three and a half years of continuous run time or 7 years of normal service. When used for LiveO2, LiveO2 AC and ExtremeO2 systems, the air separator typically runs for a few hours each session in which case the lifespan is much greater.
With a two hour per session run time on a refurbished 5 LPM air separator and a minimally estimated lifespan of 8,000 hours. The refurbished unit would provide oxygen for about 4,000 LiveO2 sessions, or in other words more than 10 years of daily LiveO2 sessions.
*It is important not to overdrive your air separator. For specific instructions on how to set your oxygen flow rate meter, follow this link: http://whnlive.com/support/air-separator-warning-light-and-alarm-sounding/