Abstract: A liquid dispenser has a cylinder in which a piston may move in an intake stroke and a discharge stroke. A pulse generator responds to any movement of the piston in the discharge direction, whereby a counting and readout device provides a dispensing measurement readout even for inadvertent discharge movements of the piston. Movement of the piston in the discharge direction rotates a wheel in the pulse generator. A ratchet system may be provided to prevent rotation of the wheel in reverse during intake movements of the piston. Alternatively the wheel rotates in both directions, and a discriminator is provided to discriminate between the two directions of movement.

Abstract: A liquid dispenser has a cylinder in which a piston may move in an intake stroke and a discharge stroke. A pulse generator responds to any movement of the piston in the discharge direction, whereby a counting and readout device provides a dispensing measurement readout even for inadvertent discharge movements of the piston. Movement of the piston in the discharge direction rotates a wheel in the pulse generator. A ratchet system may be provided to prevent rotation of the wheel in reverse during intake movements of the piston. Alternatively the wheel rotates in both directions, and a discriminator is provided to discriminate between the two directions of movement.

Abstract: A gas mixing apparatus in the form of an anaesthesia apparatus includes a first path for oxygen, a second path for nitrous oxide and third path for carbon dioxide. The first path is divided for at least a part of its length into first and second by-pass passages 210, 212. A valve 214 in the first by-pass passage 210 is inter-connected with a valve 222 controlling the flow of a nitrous oxide through the second path and a valve 215 in the second by-pass passage 212 is interconnected with a valve 232 controlling the flow of carbon dioxide through the third path. The interconnecting means 250, 260 are so arranged that the opening of the valves 222, 232 associated with the second and third paths causes corresponding opening of the valves 214, 215 associated with the by-pass passages such that the total flow of oxygen through the apparatus will never fall below a predetermined minimum proportion by volume.