US 12,264,950 B2
Method and apparatus for mass flow verification
Junhua Ding, Boxborough, MA (US); and Michael L'Bassi, Sterling, MA (US)
Assigned to MKS Instruments, Inc., Andover, MA (US)
Filed by MKS Instruments, Inc., Andover, MA (US)
Filed on Mar. 23, 2022, as Appl. No. 17/656,177.
Prior Publication US 2023/0304837 A1, Sep. 28, 2023
Int. Cl. G01F 1/42 (2006.01); G01F 1/86 (2006.01); G05D 7/06 (2006.01)
CPC G01F 1/42 (2013.01) [G01F 1/86 (2013.01); G05D 7/0629 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A mass flow verifier, comprising:
a chamber configured to receive a fluid;
a critical flow nozzle upstream of the chamber;
a chamber valve configured to selectively enable fluid flow from the critical flow nozzle to the chamber;
a downstream valve configured to selectively enable fluid flow from the chamber to a downstream location;
a bypass valve configured to selectively enable fluid flow from the critical flow nozzle to a dump location; and
a controller configured to verify flow rate of the fluid through the critical flow nozzle based on a rate of rise in pressure of the fluid as detected by a pressure sensor in the chamber by opening the downstream valve with opening of the chamber valve and closure of the bypass valve, holding the chamber valve open and closing the downstream valve to cause a rise in pressure in the chamber, thereafter closing the chamber valve and opening the bypass valve while holding the downstream valve closed to allow pressure in the chamber to stabilize, and calculating flow rate based on the stabilized pressure in the chamber.