By {TAIL ~ variation} of the liquid as well as by alteration of the porosity of the carrier {HEAD ~ the opening pressure} of the valve can be varied 
By { TAIL ~ variation } of the liquid as well as by alteration of the porosity of the carrier { HEAD ~ the opening pressure } of the valve can be varied
OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH