A fluidic flame monitoring device is disclosed, the device comprising a fdic amplifier, either of the bistable or proportional type, the power stream of which is modulated or switched in accordance with the temperature above an external flame. Connected to a control port of the fluidic amplifier is a chamber coupled to a source of fluidic pressure, the chamber incorporating a vented pressure regulating output. In the preferred inventive embodiment, an elongated thin-walled tube is coupled between the pressure regulating output of the chamber and the atmosphere, the flow resistance of the tube varying in response to the temperature of an external flame applied thereto. In one preferred embodiment, the absence of a flame alters the control signal pressure at the control port of the fluidic amplifier, switching the output power stream thereof. The switching of the output power stream is detected as an indication of flameout. When a proportional amplifier is utilized, modulation of the output power stream occurs in response to variations in flame temperature. The device can be utilized to control and shut off the fuel supply to an external burner in response to flameout.

The presence or absence of a fluid at a selected level in a tank is sensed or detected through having an expansible container, which contains fluid from the tank when the tank has fluid at the selected level, to block a pressurized gas flow path. The pressure of the pressurized gas along its flow path is determined and functions to indicate the presence or absence of fluid at the selected level in the tank.

Disclosed is an automatic valving system for shutting off liquid flow into a container when the level of liquid within the container is above a predetermined level, and for permitting liquid flow when the liquid is below the predetermined level. A liquid is positioned within the container at the predetermined level, and a pressure responsive shutoff valve is fluidly connected in series between a source of liquid under pressure and the interior of the container. The shutoff valve has communication with the fluid sensor and is operative to shut off liquid flow into the container in response to a pressure variation received from the sensor upon the level of liquid within the container rising above the predetermined level.

A non-invasive method of determining the level of fluid present in a test sample. The level of fluid present in a test sample in a container is determined by moving a pipettor toward the sample surface while aspirating air and monitoring the pressure change produced with a sensor. Non-homogeneity of the sample can be detected during the aspiration of the sample using the invention.

Methods of fluid handling are disclosed. In one method, a pump fluidly associated with a nozzle is energized to move a first fluid with respect to the nozzle. Pressure fluidly associated with the nozzle is substantially continuously monitored with a pressure transducer fluidly associated with the nozzle during movement of the first fluid. An average of the pressure substantially continuously monitored is calculated. The calculated average is used to determine a threshold. The pump fluidly associated with the nozzle is energized to move a second fluid with respect to the nozzle. Pressure fluidly associated with the nozzle is substantially continuously monitored with a pressure transducer fluidly associated with the nozzle during movement of the second fluid. The substantially continuously monitored pressure is integrated. The threshold is compared with the integrated pressure to determine whether movement of the second fluid was intended or unintended.