Patent GB-171471-A (GB)
Title: Improvements in liquid-projectors
IPC: A62C11/00
Filed: 1920-08-13
Abstract: 171,471. Tunnell, H. E. Aug. 13, 1920. Hand and portable pumps.-Relates to apparatus for discharging liquids in the form of a jet or spray for fire-extinguishing &c., consisting of a hand pump in a portable reservoir or container. The pump 23, Fig. 2, is placed to one side of the container and is secured in end blocks 24, 59 attached to the end covers 21, 22. Liquid flows to the pump through universally jointed weighted pipes 53, and is ejected from a chamber 70, Fig. 5, in the block 59 through a nozzle 61, which can be closed by a cap 64 when the piston is pushed fully home. In this position the end of the pis. ton-rod 31 pushes a slide 68 inwards against a spring, and presses the cap 64 on to the nozzle 61. When the piston is withdrawn, springs move the cap 64 and slide 68 into the position shown. During the normal movement of the piston the end of the rod 31 is clear of the slide 68. The rod 31, Fig. 4, carries a hand-grip 27 by which it is operated. There is a gap in the cap 26 and when the pump is not in use the hand-grip is turned into such a position that the projection 27<1> can pass through the gap. The grip is then turned to lock the projection under the cap. During normal working the inward stroke of the rod is limited by the projection engaging with the cap, so that the rod 31 does not engage with the slide 68. The ends of the pump-barrel 23 are in communication, through pipes 29, 58, with a central valve casing 42 made in sections as shown in Fig. 6. When the piston is moving inwards suction takes place in the outer end of the pump and liquid is drawn in through the pipe 29, passages 38, 38<11>, 44, 41, and past one or both valves 47 according to the inclination of the pump. The valves 47 are separated by a rod, so that both cannot close. The liquid in the forward end of the pump is discharged through the pipe 58, the passages 57, 72, to the pipe 71, which delivers it to the chamber 70 described above. The pressure in the passage 56 closes the ball 46. The balls 41, 46 are in slotted cages and are prevented from closing the passages 38<11>, 56 by stops. During the return movement of the piston the liquid in the inner end of the barrel is discharged through the pipe 29 to the pipe 71, the balls 39, 41 closing the passages 57, 44 respectively. At the same time the outer end is filled through the pipe 58, passages 56, 44, 44<1>, and one of the pipes 53. The pump-rod moves through a stuffing-box 30, which is screwed into the end block 24 and is provided with an adjustable gland 36. The box and packing are constructed so that air can pass into, but liquid cannot escape from, the container. The packing consists of a pad 32 of asbestos, felt, &c covered by a cupped spring-metal washer having an oval opening for the rod. Above this is a similar washer in which is placed a pad 35 of asbestos fibre &c., loose enough to allow air to pass through. An outer annular space 24a is formed between the metal washers into which the' air passes and from which it flows through perforations in the box and through the space 24* and openings 24<b> into the container. Any liquid passing along the rod is absorbed by the pad 32 until saturated. Further liquid passes through the oval hole in the metal washer into the space 24a and thence back into the container.