Critical Flow Nozzle Mass Flow Verification Without Gas-Specific Calibration
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Solution Overview
Problem
Existing mass flow verification systems require lengthy operation times due to external volume sensitivity and the need for gas-specific parameters, which affects accuracy and efficiency.
Innovation Solution
The implementation of a mass flow verifier with a critical flow nozzle, chamber valve, downstream valve, bypass valve, and a controller that enables rapid verification by measuring the rate of rise in pressure within a chamber, while being insensitive to external volumes and gas types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ROR flow verification methods are used, then flow accuracy can be verified, but the operation time is lengthy due to external volume sensitivity and gas-specific parameter requirements
Solution Approach 1:
The system divides the flow verification process into distinct phases using multiple valves (upstream valve, downstream valve, bypass valve) to segment the chamber volume from external volumes. By isolating the chamber during measurement phases, the system eliminates external volume sensitivity and enables rapid verification without lengthy stabilization periods.
Solution Approach 2:
The system changes the operational parameters of the valves dynamically during the verification process. By switching between different valve configurations (open/closed states) and using a critical flow nozzle to maintain constant pressure differential, the system achieves gas-independent measurements that are insensitive to external volumes, thereby reducing operation time while maintaining accuracy.
2Adaptability or versatility
If external volume sensitivity is present in the verification system, then comprehensive flow measurement can be achieved, but the measurement becomes dependent on gas-specific parameters and external volume characteristics
Solution Approach 1:
The verification system is designed to be universal and gas-independent by using a critical flow nozzle that maintains a constant pressure differential regardless of gas type. The multi-valve configuration enables the same device to perform multiple functions: isolating the chamber, diverting flow, and enabling various measurement modes, thereby achieving adaptability to different gases without requiring gas-specific calibration.
Solution Approach 2:
The critical flow nozzle acts as an intermediary element between the upstream and downstream sides, maintaining a stable pressure differential that decouples the measurement from external volume effects and gas-specific parameters. The bypass valve serves as another intermediary, allowing flow to be diverted away from the chamber when needed, further isolating the measurement process from external influences.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for rapid and accurate verification of mass flow rates, independent of external volumes and gas types, thereby reducing operation time and improving measurement precision.
Implementation Method 1
The critical flow nozzle is configured to maintain the fluid flowing through the critical flow nozzle at a critical flow
Implementation Method 2
verify flow rate of the fluid based on a rate of rise in pressure of the fluid as detected by a pressure sensor in the chamber
Implementation Method 3
closing a downstream valve at a first timepoint to generate a rise in pressure in the chamber
Data Source
AI summary
Devices and methods for mass flow verification are provided. A mass flow verifier includes a chamber configured to receive a fluid, a critical flow nozzle upstream of the chamber, a chamber valve, a downstream valve, and a bypass valve. The chamber valve is configured to selectively enable fluid flow from the critical flow nozzle to the chamber. The downstream valve is configured to selectively enable fluid flow from the chamber to a downstream location. The bypass valve is configured to selectively enable fluid flow from the critical flow nozzle to a dump location. The mass flow verifier further includes a controller configured to verify flow rate of the fluid based on a rate of rise in pressure of the fluid as detected by a pressure sensor in the chamber.