At Environics, all of our units are custom built for our customers' specific needs. Customers who need to dilute/mix explosive gases often come to us for help creating highly specialized systems. Most often, this is in order to calibrate gas detectors or for research or calibration purposes. To meet these unique needs, Environics designed a modified version of our Series 4040 gas dilution system which included a dual chassis design.
The electronics enclosure includes the power supply and PC boards for controlling the Mass Flow Controllers (MFC) and direct acting solenoid valves in the second enclosure. The electronics enclosure connects to a computer via a 9 pin serial port connector and cable. The 4040 software, on the computer, communicates with the microcomputer board inside the electronics enclosure.
The second enclosure is sealed and houses the MFCs, valves and components to support the enclosure purge. A continuous purge flows through the enclosure while it is running. This serves two purposes. The first is to carry out heat built up by the internal components. The second is to dilute any potential leaks that may develop. The gas plumbing inside this enclosure was vacuum leak tested to 1X10-8 ATM CC/SEC He.
In addition to continuous purge flow, the enclosure is pressurized to approximately 5” H20 while running the enclosure purge. This provides and indicator that the purge is activated as well as preventing any air leaks into the enclosure from outside. A safety vent was added to vent the enclosure to atmosphere if the pressure inside the enclosure reaches 20” H20. This could happen if for some reason the purge vent becomes blocked or the pressure on the purge rotameter is too high.
The two enclosures are connected electrically via two control cables labeled MFCs and VALVES. An earth ground wire is connected from the electronics chassis to the aluminum mounting plate inside the purged enclosure. This safely discharges any static electricity that can build up in a system with flow.
Have a similar need or need help with another unique set of conditions? You can contact us at (860) 872-1111 or here for more information.
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