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Leak & Flow testing applications Page 2
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2) Leak testing shower mixer units:
Testing of this mixer assembly was taking considerable time using the existing method of pressurising the unit, after blocking off the three holes, and then submerging the unit under water too watch for bubbles over 30 seconds. This method not only created a major bottleneck in production but also resulted in operators passing leaky units. We used a pressure decay measuring instrument that tested the units in 5 seconds with a clear pass / fail indication. The bottleneck was removed and quality improved!!
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3) Testing for correct aerosol nozzle hole sizes:
An international manufacturer of aerosol spray caps needed to 100% test assembled caps to ensure correct end user operation. Each of the customer's machines produced caps at up to 6 per second, with one reject in 10,000 being unacceptable SPC methods would not work. As measuring air flow would take too much time, approximately 1 second per test, the only alternative was to offer a solution based on 6 Mini-Flow instruments and a high speed carousel, this solution appeared expensive for the product's value but was the only way to test at this speed. Note, as there were 6 instruments each instrument had 1 second to test its component at full speed, this solution worked well and is under evaluation with more units required.
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4) Fibre tip pen nib testing for correct ink flow rates:
A large German manufacturer of drawing instruments needed to check that the pen nibs, for its disposable range of fibre tip pens, would flow the correct amount of ink - different ink colours require a different flow rate. The present method of testing was to get a sample, attach a standard ink cartridge to it, wait for the ink to be absorbed and then to draw with it at different speeds onto paper to check for correct ink flow, not a very satisfactory method for a high volume product! Samples were supplied to us and using our Mini-Flow instrument we quickly determined that accurate measurements were possible. Immediately the prospective customer asked for a demonstration unit for evaluation - 3 weeks later we were told that they were keeping the instrument and required another quickly! 18 months later and another Mini-Flow was ordered.
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5) Checking carburettor jets for correct flow characteristics:
A large, well known German manufacturer of garden power tools i.e. lawnmowers, chainsaws etc. required tighter control of the tiny carburettor jets used for these small engines, this was due to the stricter rules on engine emissions. Their supplier, based in Ireland, were using Solex type air gauges but were now faced with tolerances of +/- 3 mm of liquid column height, the errors with reading the liquid height were now significant. Samples of the jets were sent to us and we showed that the Mini-Flow had 10 times the resolution as well as unambiguous digital displays and pass / fail lamps, however, the sensitivity of the Mini-Flow showed up problems with the temperature change of the flowrate of the jets, this caused the supplier great concern as they had not been able to see this previously. The end result was that they preferred to not see this effect and to continue using the Solex gauges, even though we had proved the worth of the Mini-Flow!
This example allowed us to examine the difference of using air to gauge jets which were to flow liquid, after many tests we were more than happy to report that air gauging gave a similar deviation of flowrate than with a liquid.
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March Designs & Measurements
Unit 11, Alfred Street
Dunstable
Beds LU5 4HZ England
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