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The WAPI (Water Pasteurization Indicator) is a reusable, inexpensive device employing a plug of soy wax which melts at 65 degrees centigrade (the temperature of water at which all living organisms are killed)The wax is encased in a small tube of clear plastic which is suspended in a container of water using a length of fishing line.
[[Image:Wapi-before-after.jpg|thumb|right|200px| A WAPI showing before (left) and after (right) position of the wax]]
The WAPI (Water Pasteurization Indicator) is a reusable, inexpensive thermometer employing a plug of soybean wax which melts at 68˚C, just above the 65˚C or 149˚F pasteurization temperature for water or milk, at which point all disease-causing organisms (bacteria, viruses, and parasites) are killed.   


Since the water is not heated all the way to boiling, and merely reaches the pasteurization temperature, time is saved and less fuel is consumed.
[[Image:.284jpg|Fig 1: Women checking the wax in their WAPI after heating water in a solar cooker to 65C]]
 
==Construction and use==
The hydrogenated soybean oil called Myverol 18-06 K (a food-grade emulsifier powdered wax) is encased in a small clear plastic tube, weighted with a metal washer. Fishing line or wire suspends the WAPI toward the bottom of the water container (where the water is coolest). The WAPI is oriented with the wax plug at its top, but after melting the wax flows to the bottom part. Then the user can remove the WAPI by the string or wire without contaminating the clean water with the fingers.
 
==External links==
*[http://solarcooking.wikia.com/wiki/Water_Pasteurization_Indicator Solar Cookers World Network Wiki article on the WAPI]
*[http://solarcooking.wikia.com/wiki/WAPI_production_information Buying vs making your own WAPI]
*[http://shop.solarcookers.org/?pn=WAPI&cn=Water+Pasteurization&p=630&c=31 WAPIs for sale from Solar Cookers International].
*[http://makewapis.blogspot.com/2007/03/how-to-make-wapis.html How to make WAPIs]
*[http://solarcooking.org/phpBB2/viewtopic.php?p=82&sid=ef8dae20a4e79b4fa8fd4ceacdc08755 Making a WAPI from a ballpoint pen]
 
[[Category:Water purification]]
[[Category:Solar]]
[[Category:Solar cooking]]

Revision as of 19:01, 13 February 2013

A WAPI showing before (left) and after (right) position of the wax

The WAPI (Water Pasteurization Indicator) is a reusable, inexpensive thermometer employing a plug of soybean wax which melts at 68˚C, just above the 65˚C or 149˚F pasteurization temperature for water or milk, at which point all disease-causing organisms (bacteria, viruses, and parasites) are killed.

Since the water is not heated all the way to boiling, and merely reaches the pasteurization temperature, time is saved and less fuel is consumed.

Construction and use

The hydrogenated soybean oil called Myverol 18-06 K (a food-grade emulsifier powdered wax) is encased in a small clear plastic tube, weighted with a metal washer. Fishing line or wire suspends the WAPI toward the bottom of the water container (where the water is coolest). The WAPI is oriented with the wax plug at its top, but after melting the wax flows to the bottom part. Then the user can remove the WAPI by the string or wire without contaminating the clean water with the fingers.

External links

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