lower position in fig1 b the pilot is shown in its upper position and the poppet assembly is shown in its lower position with poppet 31 engaged with poppet seat 13 to block fluid flow through the tool when the valve is opened as poppet 31 moves out of engagement with poppet seat 13 fluid moves from inlet passage 41 through fluid passages 42 43 44 45 46 and 47 to an outlet passage 48 fig2 a 2 b and 2 c show a detail of the seal area with the poppet and pilot in various positions as the poppet closes and the pilot shifts detail area b of fig1 b which illustrates the split ring seal area is shown in fig2 a 2 b and 2 c respectively as detail b 1 b 2 and b 3 detail b 1 in fig2 a shows piston 33 moving downwardly with pilot 36 in its upper position fluid passage 44 is at a relatively high pressure and is in fluid communication through a slit 49 and a passage 50 with a cavity 51 that contains a split ring 40 this split ring is split at reference letter 61 as shown in fig3 so that it can be sprung open and is thus elastomerically biased to form an interference fit around the outer surface of piston 33 an outer diameter.