Exhaust Filter Module With Positionable Scan Probe
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Solution Overview
Problem
In cleanroom applications, particularly in filtered exhaust systems, it is challenging to perform leak testing on filters due to limited access downstream of the filter, which may lead to inaccurate results when reversing airflow, posing health and regulatory risks.
Innovation Solution
A filter module with a mechanically positionable test probe that extends into the interstitial space behind a structure, allowing for scan testing in the same airflow direction as operation, using a housing with a motion mechanism to move the probe within the module for comprehensive leak detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scan probe is positioned downstream of the filter for leak testing, then the filter can be tested in its installed location, but the limited space downstream makes positioning difficult or impossible
Solution Approach 1:
The scan probe is nested within the filter housing structure, allowing the probe to be stored and operated within the same space as the filter assembly. This eliminates the need for external positioning equipment and enables the probe to access the filter surface from the downstream side without requiring additional interstitial space.
Solution Approach 2:
The probe is positioned through the housing structure from the upstream side, utilizing the vertical dimension of the filter assembly rather than requiring lateral access from the downstream side. This dimensional approach allows testing without needing additional horizontal space in the limited downstream area.
2Ease of operation
If the scan probe is positioned from the clean room side with reversed airflow, then access is facilitated, but pin hole filter leaks may not be detected due to flow direction dependence
Solution Approach 1:
Instead of reversing the airflow direction to access the filter from the clean room side, the probe is positioned from the downstream side with airflow flowing in the normal operational direction. This inverts the approach: rather than changing flow direction to gain access, access is gained to maintain proper flow direction, thereby detecting pinhole leaks that are flow-direction dependent.
3Ease of operation
If testing is performed with reversed airflow to facilitate scanning from the clean room side, then technician access is improved, but health hazards and regulatory issues arise from potentially leaking filters
Solution Approach 1:
The approach inverts the conventional testing method by positioning the probe from the downstream side rather than the clean room side, allowing testing to be performed with airflow in the normal operational direction. This eliminates the health hazards associated with reversed flow testing while maintaining technician access through the housing structure.
Solution Approach 2:
The filter housing structure itself provides the access pathway for the probe, eliminating the need for technicians to break through structural barriers or access the downstream side directly. The housing serves its own testing infrastructure, allowing safe testing without compromising the pressure barrier or exposing technicians to potential leaks.
Data Source
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AI summary
Embodiments of the invention generally provide a filter module having a mechanically positionable test probe disposed therein and a method for testing a filter. In one embodiment, a filter module includes a housing adapted to receive a filter element. A sample probe suitable for leak testing the filter element is disposed in the interior volume of the housing. The sample probe may be moved to scan the filter by an actuator. In another embodiment, a method for testing a filter includes challenging a room side of a filter element disposed in a housing with a test aerosol, moving a probe disposed within the housing to obtain samples for testing and determining if the samples exceed a predefined leak criteria.