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Pumps and Systems Leak
Pumps and Systems Leak testing on progressing cavity pumps Fig. 3: To find the right specification and produce a practical test solution, the company experimented with a pilot system for the series-production assembly of small pumps. apply the preserving agent. While this is not a crucial issue on durable stainless steel pumps, standard pumps – which are often made of more inexpensive carbon steel – have an increased risk of corrosion on the rotor. The procedure also uses 10 l of test medium, which is critical considering the growing worldwide shortage of drinking water. Health and safety aspects should also be considered: After successfully completing the test, the water has to be drained from the pump in the test bench. It runs onto the workshop floor and then through drainage channels and into the sewer system, creating wet surfaces that are a slipping and accident risk for the staff. Other advantages of compressed air testing: saving resources while increasing safety and customer satisfaction While a leak test with water takes 5 to 15 minutes, this period is reduced to 1.5 to 5 minutes when testing with compressed air. This reduces the processing time on the test bench by 30 per cent overall – despite the installation of the equipment for a compressed air test requiring more time and greater precision. In addition, the 10 l of drinking water needed per test can be completely omitted, saving not only water but also ensuring a clean and safe workstation – no more slipping hazards around the test bench. In addition to all this, the time required for drying the pump and applying corrosion protection to flanges and threads can be omitted entirely. Overall, the compressed air leak test developed by the pump manufacturer is a reliable, SAP-compatible process that can be conducted flexibly with a mobile test trolley while significantly reducing quality problems caused by corrosion. The purchasing costs for the system are just under 17,000 euros, resulting in a payback period of the investment costs for the manufacturer of only six months when all potential savings from the new test solution are taken into account. As the process for conducting the pressure tests with compressed air increases health and safety as well as customer satisfaction, the system has been used since August 2021 for testing all pumps of the sizes NM 003 and NM 063. It is only for pumps NM 076 and larger that the company still uses water as a test medium because the large empty volume means that test section cannot settle with compressed air within an adequate time. Since 1 October 2021, the Indian subsidiary in Goa has also successfully used the new process for leak testing. A changeover is scheduled for other factories worldwide. The Author: Dipl.-Ing. (FH) Johann Vetter, Director of Integrated Quality Management, NETZSCH Pumpen & Systeme GmbH, Waldkraiburg, Germany 40 PROCESS TECHNOLOGY & COMPONENTS 2022
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