SINGLE CELL PURIFIERS (RSD-5 through RSD-100)
Pure and bleed gases exit the permeation cell at 800F. Both are cooled by natural convection, which cannot fail, rather than by fans or blowers, which can.
"SET AND FORGET" BLEED FLOW
Bleed flow control and indication is provided by a front panel rotameter and a line pressure regulator. As long as feed pressure is maintained above 50 PSI, a constant pressure is presented to the bleed rotameter, which then maintains a constant flow.
A check valve in the bleed line prevents air from migrating back in the bleed line after the unit is shut down. This removes the need to close the bleed flow valve on shut-down
FORMAL FEED GAS PREHEATING
The Feed Gas enters the permeation cell by passing along the outside of a cartridge heater well. The Feed Gas traverses the full length of the heater well before it reaches the permeation tubing. No competetive system provides formal preheating.
FEED GAS CHECK VALVE
A check valve on the feed line prevents sudden decompression of the feed side of the system and protects the permeation tubing from back pressure.
HIGH TEMPERATURE CONTROL AND ALARM (NOT SHOWN)
A second temperature control breaks the furnace line mechanically (and sounds an alarm) whenever the cell temperature rises 50F above the main control point. The second control temperature is still safe for operation and the unit does not shut down! The choice of when to shut down is left to the operator, who may wish to continue production for a reasonable period prior to removing the purifier from service.
Purifiers larger than 100 SCFH (Models RSD-150 and up) use multiple cells in parallel and incorporate appropriate modificationsof the features listed above.