Abstract: A choked-flow orifice gas gauge proximity sensor for sensing a difference between a reference surface standoff and a measurement surface standoff is disclosed. Unlike existing proximity sensors, the gas gauge proximity sensor of the present invention replaces the use of a mass flow controller with a choked flow orifice. The use of a choked flow orifice provides for reduced equipment cost and improved system reliability. A gas supply forces gas into the proximity sensor. The gas is forced through the choked flow orifice to achieve sonic conditions at which time the mass flow rate becomes largely independent of pressure variations. The flow of gas proceeds from the choked flow orifice into a sensor channel system. A mass flow sensor within the sensor channel system monitors flow rates to detect measurement standoffs that can be used to initiate a control action.

Abstract: A vacuum-driven gas gauge proximity sensor for sensing a difference between a reference surface standoff and a measurement surface standoff is disclosed. Unlike existing proximity sensors, the vacuum-driven gas gauge proximity sensor uses a vacuum to reverse the traditional flow of gas through a proximity sensor, such that gas flows inward across measurement and reference standoffs through measurement and reference nozzles. The conditioned ambient gas that is vacuumed into the reference and measurement nozzles flows through reference and measurement channels that are coupled at a junction into a single channel. The single channel is coupled to the vacuum that is used to evacuate the conditioned ambient gas through the proximity sensor. A bridge channel couples the reference and measurement channels. A mass flow sensor along the bridge channel monitors flow rates to detect measurement standoffs that can be used to initiate a control action. A pump-driven liquid flow proximity sensor is also disclosed.

Abstract: A choked-flow orifice gas gauge proximity sensor for sensing a difference between a reference surface standoff and a measurement surface standoff is disclosed. Unlike existing proximity sensors, the gas gauge proximity sensor of the present invention replaces the use of a mass flow controller with a choked flow orifice. The use of a choked flow orifice provides for reduced equipment cost and improved system reliability. A gas supply forces gas into the proximity sensor. The gas is forced through the choked flow orifice to achieve sonic conditions at which time the mass flow rate becomes largely independent of pressure variations. The flow of gas proceeds from the choked flow orifice into a sensor channel system. A mass flow sensor within the sensor channel system monitors flow rates to detect measurement standoffs that can be used to initiate a control action.

Abstract: A vacuum-driven gas gauge proximity sensor for sensing a difference between a reference surface standoff and a measurement surface standoff is disclosed. Unlike existing proximity sensors, the vacuum-driven gas gauge proximity sensor uses a vacuum to reverse the traditional flow of gas through a proximity sensor, such that gas flows inward across measurement and reference standoffs through measurement and reference nozzles. The conditioned ambient gas that is vacuumed into the reference and measurement nozzles flows through reference and measurement channels that are coupled at a junction into a single channel. The single channel is coupled to the vacuum that is used to evacuate the conditioned ambient gas through the proximity sensor. A bridge channel couples the reference and measurement channels. A mass flow sensor along the bridge channel monitors flow rates to detect measurement standoffs that can be used to initiate a control action. A pump-driven liquid flow proximity sensor is also disclosed.