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Sap Value Calculator

Use this online calculator to determine the proper price to pay for sap.

Check-valve spouts vs. standard clear spouts

Leader Evaporator Co. Check-Valve (CV) spouts and adapters incorporate a small, free-floating ball which is designed to reduce or prevent backflow of sap into the taphole during freezing, when leaks in the tubing system occurs, and when mechanical releasers dump and introduce air into the system. Several studies over nearly a decade have compared sap yields from CV adapters and spouts to various non-CV spouts and adapters.

Tapping Zone Model – Tubing

This model estimates the proportion of clear, conductive wood in the tapping zone of an individual tree each year (for 100 years) based on the values input for tree diameter, tapping depth, spout size, number of taps, and dropline length. This is equivalent to the chances of tapping into conductive wood in this tree each year Ð if 80% of the wood in the tapping zone is conductive, you have an 80% chance of hitting conductive wood when you tap that tree. The model can be used to estimate whether various tapping practices are likely to be sustainable. A more complete description of the model and guidelines for its use can be found in the companion technical report “A Model of the Tapping Zone”, which is available on the UVM-PMRC website (

3/16 inch Tubing with Check Valves Trial

In a normal sap flow event, trees exude sap during the above freezing period and replenish that lost water by ÒsuckingÓ it up from the roots during the below freezing period. If on a tubing system, during this negative pressure period they tend to draw sap back into the tree from the dropline. Sap, once it enters the droplines, is quickly contaminated with microbes. When they are drawn back into the tree, tap hole closure is initiated. The problem is compounded in 3/16- inch tubing because, unlike 5/16-inch tubing, the smaller diameter collection tube remains full of sap. A Cornell study found that up to 12 feet of sap in a 3/16-inch tube can be drawn back into the tree during this recharge time. CV spouts are one proven method of limiting this drawback with 5/16 inch tubing. The question was: will they also be effective with 3/16-inch tubing that is full of sap?

Does Color Matter? Spouts come in variety of hues. Does it affect yield?

In general, it is presumed that any effect of Òspout colorÓ on sap yield arises due to thermal warming of darker-colored spouts during sunny periods. Darker-colored spouts warm faster and the spout temperature can rise considerably above air temperature when hit by the sun compared to lighter-colored spouts. To assess the effect of Òspout colorÓ on sap yield, we conducted a multi-year study at the University of Vermont Proctor Maple Research Center in Underhill, Vermont. Twelve treatment plots were randomly assigned a different spout type, with one mainline and releaser for each plot.