Comparative Table of Technologies Available on the Maple Sugaring Market
| Advantages | Risks/Disadvantages | |
| Oil-lubricated rotary vane vacuum pumps |
› Vacuum level of 29.9’’ Hg
› Wide range of flow rates › Constant flow rate from the atmospheric pressure to the end vacuum › Simple design › Quiet operation |
› Risk of oil contamination by sap
› Risk of oil expulsion between 0-20’’ Hg Maintenance: – Frequent oil and filter changes – Wear of vanes if maintenance is faulty |
| Dry claw vacuum pumps | › Vacuum level of 28.4’’ Hg
› Constant flow rate from the atmospheric › Constant flow rate over time (no wear parts) › Simple design › Quiet operation › Proven technology in maple syrup production Maintenance: – Almost non-existent – No fluid in the compression chamber |
› More limited vacuum level on models over 130 CFM (27’’ or 25.5’’ Hg) |
| Dry-running rotary vane vacuum pumps |
› Simple design
› Quiet operation |
› Vacuum level limited to 25.5’’ Hg
› Low capacity vs power output › Capacity loss of up to 30% because of › Risk of clogging with the mixture of maple Maintenance: – Frequent and expensive vane changes |
| Liquid ring vacuum pumps | › Vacuum level of 28.9’’ Hg (double stage)
› Wide range of flow rates › Quiet operation › Tolerant to maple sap Maintenance: – Almost non-existent |
› Low capacity vs power output (less CFM for the same HP)› Variable performance based on water temperature› Water consumption› Complex oil recirculation system |
| Lubricated screw vacuum pumps | › Vacuum level of 29.9’’ Hg
› Wide range of flow rates › Quiet operation |
› Variable performance
› Actual consumption higher than the motor › Complex design with multiple components › Electronic system often required for operation › Risk of oil contamination from maple sap Maintenance: – Frequent oil changes and part – Complex and expensive on-site |
Did You Know That:
- Nature may abhor a vacuum, but maple producers don’t
The job of a vacuum pump is to reduce the amount of air in a tubing network. Removing the air reduces the pressure. What we measure in ’’ Hg is the pressure difference between the ambient air and the interior of the network. Nature works hard to fill the void by pushing air from a high pressure to a low pressure. It is this pressure difference, applied through the tree, that increases sap production. - Best vacuum, best sap production
According to a study by the University of Vermont*, a better vacuum can save up to 5% more maple sap per additional ’’ Hg without any negative effect on sap chemistry, sugar content or the tree’s health. - Vacuum level matters, especially at the tree!
Measure the vacuum level difference between the end of your lines and your releaser when sap runs. For every extra ’’ Hg between the two, another 5% of production is lost. - Small leaks become very large under vacuum
The better the vacuum, the more space is taken up by air. Leaks of 1 CFM at 15’’ Hg become 3 CFM at 25’’ Hg, 5 CFM at 27’’ Hg and 15 CFM at 29’’ Hg. This means leaks become 3, 5 or 15 times bigger under vacuum, which involves just as many more steps in the woods to repair them. - The optimal vacuum level for maple syrup production is between 25’’ and 27’’ Hg
A vacuum pump that reaches 29’’ Hg is easy to find. A network that can maintain 29’’ Hg during production and throughout the season is much more difficult and expensive to achieve, even unrealistic in most cases. As a result, a 25-27’’ Hg vacuum is the best option for maximizing your maple sap production at reasonable network costs. - At high altitudes, there is less air to remove
If we are at altitude, the barometric pressure is lower. The pressure reserve is also lower, so we can create a smaller pressure difference with a vacuum. Regardless of the vacuum pump, we inevitably lose about 1’’ Hg per 1,000 feet of altitude. - The largest pump in the world will never replace leak checking
With an oversized pump, it is possible to reach a good vacuum level without having to repair leaks in the network. However, this is strongly discouraged. Leaving too many leaks could freeze and block the tubing lines.