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