The first reaction chamber is arranged in {TAIL ~ continuous fluid communication} with the downstream conduit and has {HEAD ~ a preselected first effective surface area} 
The first reaction chamber is arranged in { TAIL ~ continuous fluid communication } with the downstream conduit and has { HEAD ~ a preselected first effective surface area }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD