MCS sampling systems can be operated in automatic or manual modes. Manual operation enables quick sampling or convenient system purging. For fully automatic sampling or system purging, the MCS systems use an easy-to-program timer that permits up to 294 on/off events, over a 7-day time span. While the sample is being taken, the total elapsed sample time is being recorded. This feature is particularly useful as confirmation that the system has not experienced any power failures. The many features of MCS series canister samplers ensure the repeatable and reliable collection of high integrity air samples.