MANUFACTURING METHODS FOR PRODUCING WATER PASTEURIZATION INDICATORS (WAPI)

摘要

Securing safe drinking water in developing countries is a significantly important problem for engineers to be aware of. Out of 6.5 billion people in the world, 1.1 billion people still do not have access to safe drinking water in their daily lives. A team lead by the Department of Biological Science at our institution developed a prototype device called Water Pasteurization Indicator (WAPI). This device is used to check if water temperature heated by a solar ray reflector panel reached above the pasteurization temperature. The WAPI consists of Carnauba wax in a polycarbonate tube with both ends sealed, a washer for adding weight and setting up the orientation of a WAPI when it is submerged in water, and a fishing string for pulling the WAPI out of water. This paper describes development of a mass-production method for WAPIs. It is essential to establish a mass production method for WAPIs so that it can be made available to people in developing countries in large quantities with an affordable price. The manufacturing method was developed considering appropriate technologies which can be adapted by people in developing countries. In addition, the manufacturing method should be simple, economical, productive, and consistent in quality of WAPIs produced. After the prototype WAPI processing device was developed, a full-factorial design of experiment (DOE) was conducted to optimize three critical process parameters for sealing both ends of a polycarbonate tube by a pair of heat-clamping plates. These parameters are claming temperature,claming time, and clamping gap. During the period of Summer 2004 through Spring 2005, approximately 2000 WAPIs were produced by the WAPI processing device and were sent to Kenya and Tanzania, and all were tested to work successfully.