Abstract: A method and apparatus for aspirating and dispensing a sample fluid. The apparatus includes an air source having an output port coupled to a first port of a flow through pressure transducer. A second port of the flow through pressure transducer is coupled to a first port of a sample probe. The flow through pressure transducer provides transducer signals to a detector circuit. In response to the transducer signals provided thereto, the detector detects the occurrence or non-occurrence of a plurality of different events.

Abstract: A liquid supply module includes one or more sets of bulk liquid containers each supplying a respective reservoir via a liquid supply line. The bulk liquid containers and reservoirs are vented above the highest liquid level in the system. A pump periodically removes a known volume of liquid from a reservoir which is replenished from a bulk liquid container. A sensor detects a liquid/air transition in the liquid supply line to the reservoir indicative of the exhaustion of liquid resupply from the bulk liquid container. Art air vent solenoid valve in communication with the reservoir is closed when an empty bulk liquid container is replaced. Normal pump operation siphons liquid out of the bulk container after container replacement. A control system tracks pump iterations and calculates a number of executable iterations remaining before the reservoir runs dry.