{HEAD ~ Such sensors} may, alternatively, detect {TAIL ~ the pressure} of the fluid on either side of the piston head of such a system, for example 
detect
{ HEAD ~ Such sensors } may , alternatively , detect { TAIL ~ the pressure } of the fluid on either side of the piston head of such a system , for example
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH