Mks Instruments, Inc.

Daniel Alexander Smith

Ali Shajii

Matthew Mark Besen

Siddharth P Nagarkatti

William R Clark

Bora Akgerman

Junhua Ding

Kaveh H Zarkar

Paul Michael Meneghini

A system for delivering a desired mass of gas, including a chamber, a first valve controlling flow into the chamber, a second valve controlling flow out of the chamber, a pressure transducer connected to the chamber, an input device for providing a desired mass to be delivered, and a controller connected to the valves, the pressure transducer and the input device. The controller is programmed to receive the desired mass from the input device, close the second valve and open the first valve, receive chamber pressure measurements from the pressure transducer, and close the inlet valve when pressure within the chamber reaches a predetermined level. The controller is then programmed to wait a predetermined waiting period to allow the gas inside the chamber to approach a state of equilibrium, then open the outlet valve at time=t, and close the outlet valve at time=t* when the mass of gas discharged equals the desired mass.

Pulsed mass flow delivery system and method

A flow verifier for verifying measurement by a fluid delivery device under test (DUT) includes a chamber configured to receive a flow of the fluid from the DUT, at least one temperature sensor to provide gas temperature in the chamber, at least one pressure transducer to provide gas pressure in the chamber, and a critical flow nozzle located upstream of the chamber along a flow path of the fluid from the DUT to the chamber. The critical flow nozzle and the flow verification process are configured to maintain the flow rate of the fluid through the nozzle at the critical flow condition such that the flow rate through the nozzle is substantially constant and substantially insensitive to any variation in pressure within the chamber downstream of the nozzle. Therefore, the varying chamber pressure during the flow verification period has substantially no impact on the downstream pressure of the DUT, and the external volume between the flow verifier and the DUT is substantially irrelevant to the flow verification calculation.

Critical flow based mass flow verifier

A flow verifier for verifying measurement of a flow rate of a fluid by a device includes a flow restrictor that renders the flow rate verification substantially insensitive to elements upstream of the flow restrictor. The flow verifier includes a vessel that receives a flow of the fluid from the device, and a pressure sensor that measures pressure of the fluid within the vessel. An outlet valve regulates flow of the fluid out of the vessel. The flow restrictor is located adjacent to and upstream of the vessel, along a flow path of the fluid. The flow restrictor restricts the flow of the fluid so as to induce a shock in the flow path of the fluid, and sustains the shock during a time period sufficient to render the flow rate verification substantially insensitive to the elements upstream of the flow restrictor.

Mass flow verifier with flow restrictor

A flow verifier for in-situ verification of a device under test (DUT), including an inlet connectable to a DUT, an outlet connectable to a vacuum pump for drawing gas through the DUT and the flow verifier, a vessel having a predetermined volume, diffusive media connecting the inlet to the vessel, an outlet valve connecting the vessel to the outlet for controlling flow from the vessel to the outlet, at least one temperature sensor operatively connected to the vessel for providing temperature measurements from within the vessel, and a pressure transducer operatively connected to the vessel for providing pressure measurements from within the vessel.

External volume insensitive flow verification

A flow rate sensor includes a main conduit, a sensor tube and a bypass tube connecting an upstream portion of the main conduit to a downstream portion of the main conduit such that flow through the main conduit is divided through the sensor tube and the bypass tube, and at least one heater element for heating the sensor tube. A first flow restrictor of porous media is positioned between the upstream portion of the main conduit and the sensor tube, and a second flow restrictor of porous media is positioned between the upstream portion of the main conduit and the bypass tube. The flow restrictors provide the flow rate sensor with a fixed bypass ratio so that the sensor can operate independently of the type of gas being measured.

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Andover, MA, United States of America

Daniel Alexander Smith