Patent ID: 7832252

Claim:
In an instrument system for producing a carefully metered droplet of a desired liquid to be injected into the inlet or throat of a scientific measuring instrument for the purpose of calibrating that instrument, the (combination) apparatus comprising: a liquid reservoir from which droplets may be drawn; a pump to supply gas to the interior of the resevoir for maintaining gas pressure in the space not occupied by the liquid; a confined path coupling the pump to the reservoir through which the pump may provide pressurized gas to the reservoir, the confined path having a check valve in a series relationship to prevent back-flow of the gas; a pulse valve coupled to the reservoir and selectively operable for withdrawing a droplet from the liquid reservoir and (and) applying a forward velocity to it; and electronic control means selectively operable for activating the pulse valve for a predetermined time interval within which a selected droplet is to be drawn from the reservoir.