The Apex AFD-510 is designed to be an easy, convenient, and compact way to control the flow of both stack and calibration gases. This new panel can flow gas to either the analyzer bank (Direct calibrations) or the probe (System calibrations), and has both automatic and manual controls. This unit has been designed with simplicity in mind. It has the same common solenoids and a simplified wiring protocol. The calibration gas in use is identified by a LED along with which mode you are in and if you are sampling or calibrating. One big benefit of the Apex Instruments AFD-510 is that in sampling mode all solenoids are at "rest" which greatly extends the life of the unit.