Abstract: An analog flow meter instrument includes a flow meter monitoring the flow of fluid. A sensor unit is secured to the flow meter and include an indicator rod in an oil filled tube. The rod extends into the flow meter and is positioned in accordance with the flow. The sensor includes a housing having a slot to visually read the location of the rod. A light beam unit is mounted to one side of the tube and a plurality of phototransistors in a linear array are mounted to the opposite side of the tube. The phototransistors are connected in a current summing network to generate an analog current signal, the amplitude of which is linearly related to the fluid flow. The output signal is amplified and connected to output devices. The analog signal can be reliably transmitted over relatively long distances within the factory environment using conventional low voltage wiring.

Abstract: A linear digital flow meter includes a float in a passageway as is located positioned with the rate of flow. A sight glass tube is secured to the end of the unit and a rod connects the float to a tube. A generally H-shaped housing has the tube located in an opening in the cross bar with a light chamber to one side and a detector chamber to the opposite. A bank of LEDs in the light chamber is aligned with a transmitting slot and a bank of phototransistors is aligned with a receiving slot in the detector chamber. A shadow mask between the phototransistors and the slot concentrate the light so the phototransistor receive light according to the length of rod in the sight glass. A bottom connector chamber is in the bottom of the housing with L-shaped passages to the light and detector chambers with the appropriate leads to the lamp and detector chambers. A multiplexer connects the phototransistors to a microprocessor which stores and processes the signal.

Abstract: A gas flowmeter includes an oil-filled tube coupled to the gas flow line and a float lifted by gas flow. An LED lamp transmitter and a photoresistor receiver are coupled to a guard telescoped over the tube. The LED lamp has an integrated concentrating lens to define a concentrated sharp beam passing through a small barrel located in a guard slot for close coupling the light beam to the tube. The photoresistor receiver includes a similar barrel in an opposite slot in accurate alignment with the transmitter barrel. The receiver includes a photoresistor connected in a dividing network to define an input node to a regenerative "Schmitt" switch which actuates a solid state control relay to indicate a limit position of the float. A mounting plate has a correspondingly mounted light transmitter housing and photoresistor housing. The housings are formed from the same casting. The housings include similar integral clamping tongues located in slots on the opposite sides of the guard.