Mainline size for gravity/vacuum

[pdr]

I will have approximately 3500 taps on steep slope, fairly evenly distributed along 2500' of open-ended, 5-7% sloped mainline. I expect to average 25-35 taps on 3/16" laterals, each of which will have 150' to 300' elevation change. Table 6.4 (pg. 98) in the North American Maple Syrup Producers Manual suggests that a 1.5" mainline will handle only 1,200-2,000 taps. Will a combination of 500' of 3/4" into 1,000' of 1.25" into 1,000' of 2" be sufficient? How should I adapt the 3/16" lateral to the larger diameter mainline? Run some 3/4" parallel to the bigger mainline and "Y" it in? Reduce from 2" & 1.5" to 3/16" for each lateral?

Also, I noticed (pg. 107) in the Manual the author suggests a wet line size of 3/4" on a dual system for 1,000 taps, a 1" for 2000 taps, 1.25" 3500 taps, etc. I assume it means that the given line size is good for up to the given number of taps. Seems like a huge discrepancy between the that and table 6.4 - i.e., the latter suggests a 1.5" mainline can 1,200-2,000 taps vs. the 3,500 taps suggested on page 107.

Just don't want to spend more than I have to. Thanks for any insight.

[DrTimPerkins]

Also, I noticed (pg. 107) in the Manual the author suggests a wet line size of 3/4" on a dual system for 1,000 taps, a 1" for 2000 taps, 1.25" 3500 taps, etc. I assume it means that the given line size is good for up to the given number of taps. Seems like a huge discrepancy between the that and table 6.4 - i.e., the latter suggests a 1.5" mainline can 1,200-2,000 taps vs. the 3,500 taps suggested on page 107.

You're comparing apples (single conductor system) and oranges (wet/dry system). A dual-conductor (wet/dry lines) system is designed for artificial vacuum, and the wet line is designed to ONLY carry a full-pipe of sap (under peak flow conditions). In a single pipe system under vacuum, the lines need to be larger to allow the vacuum to run in the upper portion of the mainline and the sap to run across the lower half.

If you're collecting sap with gravity or with natural vacuum, your lines don't have to be as large, since they aren't carrying vacuum (air). They should be sized large enough to carry primarily the liquid. If you ever do change to pumped vacuum, those lines would be undersized however.

[mountain man maple]

I don't know what brand of materials your using but lapierre makes saddles that fit up to 2" mainline. Myself I wouldnt use over 1.5" mainline have heard 2" is very hard to hold because of weight. I run around 560 gravity taps on a .75 inch mainline never runs much over half full only problem is plastic connectors bottle necking it and making place for slush to catch and back up. Myself I would start with .75 at around 600 taps go to 1" around 1500 taps jump to 1.25 and at 3000 taps go to 1.5" for remainder of taps. I would also use SS fittings to connect mainline you only will need a few for 2500 feet and will flow better.