Piston type pipette to deliver repeated measured doses - esp. for immunology tests, has setting scale indicating vol. of dose

摘要

The piston rod is passed through a slight clearance hole in a radial arm. Depression of an operating knob tilts the arm to jam the bore of the hole on the piston rod and then to displace the rod to deliver liq. Advance of the piston is limited by the arm meeting a fixed front stop. Release of the knob allows the arm to level up and to be returned under spring pressure until it reaches an axially adjustable back stop. The arm slides along the piston rod which is held by a non-return device. Axial adjustment of the back stop determines the delivery stroke length for the piston and hence the vol. of liq. delivered. This axial adjustment of the back stop is effected by rotation of a setting not coaxial around the piston rod. Rotation of the nut is transmitted to tumbler coupled counting wheels which are mounted coaxially around the piston rod. The wheels are graduated to indicate the corresponding vol. to be delivered. Used for repeated delivered of metered doses of liq. Partic. radio-immunological doses of suepsnsions of cells. The pipette is easily pre-set to the required dose. The vol. of the dose is displayed on a graduated scale. The delivery piston complete with cylinder can be easily detached for cleaning or renewal.