Automated Fixture for Leak Detection Scanning

Abstract

Price Industries designs and manufactures components for heating, ventilation and air conditioning systems. One series of products they manufacture is the Price LFDC / LFDCSS Series Laminar Flow Diffusers with replaceable high-efficiency filters. The laminar flow diffusers provide filtered air to environments where air quality is important, such as hospitals and clean rooms. The diffusers are manufactured from sheet metal, and each diffuser has various seams and joints that are tack welded and caulked. To ensure that the diffusers function as intended, each unit must undergo an aerosol challenge test to detect any leaks. The aerosol challenge test involves pressurizing the diffuser with air infused with oil particles and using a photometer to detect if the oil-infused air is escaping through any of the seams or joints. The current process involves a worker with a handheld device manually passing the device’s nozzle over the seams. The objective of our project was to design a fixture that can automatically scan each seam and joint as well as alerting the worker to a detected leak, with minimal human interaction. We were also tasked with designing the documentation system for documenting the location of leaks detected that can be tied into the barcode scanning system. After considering the constraints, limitations, customer needs and target specifications, we generated a variety of concepts. We analyze the concepts with decision matrices and determined the best concept for each component of the design. After determining the best concepts, we began the final design process. We designed a test fixture which meets all the requirements determined. Our test fixture is comprised of a manually adjustable frame, four leadscrews with guide rails, and four nozzle carriages that run along the lead screws. The adjustable frame allows the test fixture to accommodate multiple diffuser sizes. Leadscrews run along each side of the test fixture and are driven by mounted stepper motors. The leadscrews and guide rails are used to move the nozzle carriages along each side of the diffuser to scan the seams. The nozzle carriages are comprised of a simple C shaped frame where the nozzles, valves, and a...