Abstract:
A syringe comprising a cylindrical barrel with a wall at one end with a nozzle and with a threaded actuating rod extending from its other end, the rod having an axial bore and a piston in fluid tight engagement with the inner wall of the barrel is connected to the rod by compressible spring means which is an extension of the rod threads. The rod also carries a collar with threads which mate with the rod threads, and the collar has slots which engage projections on the barrel and prevent movement of the collar relative to the barrel but which permit the collar to be disengaged readily from the barrel. An indicator rod is connected at one end to the piston and is slidable in the bore of the actuating rod. The opposite end of the indicator rod, bearing graduation marks, extends axially outwardly of the actuating rod. Rotation of the actuating rod causes movement of the piston axially of the barrel when the collar is engaged, and as the pressure on fluid within the barrel increases, the spring means compresses causing the indicator rod to extend farther outwardly of the actuating rod and thereby, indicates the fluid pressure.