The transfer system yielded 27 percent more sap one year and 17 percent more the next year.
A leak-free system substantially increase the volume of sap collected. The benefits of increased sap flow in artificial vacuum systems are found throughout the season, but are best realized during poor sap flow days. Artificial vacuum systems do not pull or suck maple sap from the taphole; The process is more complex. Sap flow is generally initiated as temperatures rise above freezing. along with an associated increase in sap pressure within the tree.  Fresh sap flowing out of the maple tree contains anywhere from 1 6% sugar. Finished maple syrup is 66-67% sugar. To increase the sugar concentration of sap, many gallons of water need to be removed. For example, to produce one gallon of syrup, 43 gallons of sap with 2% sugar content are needed. This means that 42 gallons of water must be removed from the initial 43 gallons of sap. In most maple operations, the water is removed by boiling the sap Making birch syrup is more difficult than making maple syrup, requiring about 100-150 liters of sap to produce one liter of syrup (more than twice that needed for maple syrup). The tapping window for birch is generally shorter than for maple, primarily because birches live in more northerly climates. While maple sap may be boiled down without the use of reverse osmosis, birch syrup is difficult to produce this way: the sap is more temperature sensitive than is maple sap because fructose burns at a lower temperature than sucrose, the primary sugar in maple sap. Non Technical Summary. Maple sap yields typically decline each year after a mainline and tubing system is installed. The causes for this decline are unclear, however the difference between yield in the first season and yield after 5-10 years of operation can amount to 50% or more.  Abstract. Yields of sugar maple sap collected from three plastic pipeline systems by gravity, vacuum pump, and a vacuum pump with a transfer tank were compared during 2 years in northern Vermont. The transfer system yielded 27 percent more sap one year and 17 percent more the next year. Higher vacuum levels at the tapholes were observed in the transfer system. For collecting sap without vacuum, more taps will be needed to produce the same volume of sap as vacuum. Tree growth rate affects the number of taps, but a conservative starting point a trees 10-17 inches in diameter (31-53 inch circumference) should have no more than one tap. The Rule of 86 is used to calculate the gallons of sap needed to produce one gallon of syrup. It states that the number of gallons of sap you need to produce one gallon of syrup is equal to 86 divided by the percent sugar. Rule of 86Gallons of sap to produce one gallon of syrup = 86 / % sugar content in sap. For example, you would need 43 gallons of sap with 2% sugar content to produce one gallon of syru Maple sap is reminiscent of water with the exception of its slightly sweet taste. It takes 55 gallons of maple sap to produce one gallon of maple syrup. The reverse osmosis machine separates water from water-soluble solids and can reduce the boiling process in half. From the reverse osmosis machines the sap concentrate goes into the boiler. At this point it only takes approximately eleven gallons of the sap concentrate to create a gallon of maple syrup. Between the reverse osmosis process and the boiling, the sap goes from 2% or 3% sugar to 66% sugar in the final syrup. Maple syrup production in the United States is mainly in the Northeast and the northern Midwest. According to the National Agricultural Statistics Service (NASS), national production averages more than 1.3 million gallons a year with an average income of slightly over $37.5 million. The best species of maple for syrup production in Pennsylvania is sugar (often called hard or rock) maple (Acer saccharum). However, red, silver, and Norway maples may be used. Generally, the sugar content of the sap of these species is not as high, requiring more sap to produce syrup.
http://extension.psu.edu/maple-syrup/collecting/tubing-system-installation/vacuum http://maple.dnr.cornell.edu/produc/evap.htm https://en.wikipedia.org/wiki/Birch_syrup http://www.reeis.usda.gov/web/crisprojectpages/0205286-strategies-to-limit-reductions-in-maple-sap-yield-in-vacuum-installations.html http://www.nrs.fs.fed.us/pubs/1440 http://maple.dnr.cornell.edu/FAQ.htm http://branonmaple.com/making-maple-syrup.html http://extension.psu.edu/business/ag-alternatives/forestry/maple-syrup-production
how much more sap will a vacuum system produce