System and method for measuring flow

• US 20060123921A1
• Filed: 01/27/2006
• Published: 06/15/2006
• Est. Priority Date: 12/15/2004
• Status: Active Grant

• Current Assignee: Brooks Instrument LLC (Illinois Tool Works Inc.)
• Original Assignee: Shiliang Lu, Stuart A. Tison
• Inventors: Lu, Shiliang, Tison, Stuart A.
• Granted Patent: US 7,287,434 B2
• Time in Patent Office: Days
• US Class Current: 73/861
• CPC Class Codes: G01F 7/005 by measuring pressure or differential pressure, created by the use of flow constriction

Abstract

One embodiment of the present invention can comprise a primary flow measurement system, a secondary flow measurement system in fluid communication with the primary flow measurement system and a control coupled to the primary flow measurement system and the secondary flow measurement system. The controller can comprise a processor and a memory accessible by the processor. The processor can execute computer instructions stored on the memory to calculate a flow rate using the primary flow measurement system, in a first mode of operation, and calculate the flow rate using the secondary flow measurement system, in a second mode of operation. The computer instructions can be further executable to switch between the first mode of operation and the second mode of operation based on a predefined parameter.

Claims

1-41. -41. (canceled)

42. A system for determining a flow rate of a fluid, comprising:

a primary flow measurement system;

a first flow passage to direct fluid from a fluid source to the primary flow measurement system;

a secondary flow measurement system in parallel with the primary flow measurement system;

a second flow passage to direct fluid from the fluid source to the secondary flow measurement system;

a controller coupled to the primary flow measurement system and the secondary flow measurement system, the controller comprising;

a processor;

a memory accessible by the processor, the memory storing a set of computer instructions comprising instructions executable by the processor to;

determine a flow rate using the primary flow measurement system; and

determine the flow rate using the secondary flow measurement system.

43. The system of claim 42, wherein the set of computer instruction further comprise instructions executable to:

switch between a first mode of operation for determining the flow rate a second mode of operation for determining the flow rate;

wherein in the first mode of operation the computer instructions are executable to determine the flow rate using the primary flow measurement system and in the second mode of operation to determine the flow rate using the secondary flow measurement system.

44. The system of claim 42, wherein the primary flow measurement system is one of a constant volume system, a constant pressure system, or a gravimetric flow measurement system.

45. The system of claim 44, wherein the secondary flow measurement system is one of a sonic nozzle system, a laminar flow meter, an ultrasonic flow meter, a coriolis flow meter, or a thermal mass flow meter.

46. A system of determining a flow rate of a fluid comprising:

a constant volume chamber;

a sonic nozzle in parallel to the constant volume chamber;

one or more valves configured to direct a flow of a fluid to the constant volume chamber and the sonic nozzle;

sensors configured to read one or parameters of the fluid in the system; and

a controller coupled to the sensors configured to receive measurements from the sensors, the controller comprising;

a processor;

a memory accessible by the processor, the memory storing a set of computer instructions comprising instructions executable by the processor to;

determine a flow rate based on one or more parameters of fluid as the fluid accumulates in the constant volume chamber; and

determine the flow rate as the fluid flows through the sonic nozzle.

47. The system of claim 46, wherein the set of computer instruction further comprise instructions executable to:

switch between a first mode of operation for determining the flow rate a second mode of operation for determining the flow rate;

wherein in the first mode of operation the computer instructions are executable to determine the flow rate using as fluid accumulates in the constant volume chamber and in the second mode of operation to determine the flow rate as the fluid flows through the sonic nozzle.

48. The system of claim 47, wherein, in the first mode of operation, the flow rate is calculated based on the change in pressure over time of the fluid.

49. The system of claim 48, wherein the instructions executable to calculate the flow rate based on a change in pressure over time as the fluid accumulates in the constant volume chamber according to

50. The system of claim 47, wherein, in the second mode of operation, the flow rate is calculated based on a fluid pressure.

51. The system of claim 47, wherein, in the second mode of operation, the flow rate is approximately calculated according to

62. A method of determining a flow rate of a fluid comprising:

supplying fluid to a constant volume chamber;

supplying fluid to a sonic nozzle in parallel with the constant volume chamber;

for a first mode of operation, calculating the flow rate as fluid accumulates in a constant volume chamber for a first range of flow rates; and

for a second mode of operation, calculating the flow rate as the fluid flows through the sonic nozzle for a second range of flow rates; and

switching between the first mode of operation and the second mode of operation.

63. The method of claim 62, wherein, in the first mode of operation, the flow rate is calculated based on the change in pressure over time of the fluid.

64. The method of claim 63, further comprising calculating the flow rate based on a change in pressure over time as the fluid accumulates in the constant volume chamber approximately according to