Tapping and Tubing

Tips for Working Volunteers into Your Maple Woods

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Whether you have children eager to help or new volunteers wanting to participate in your woods, you are undoubtedly familiar with the tug-of-war.  On one side, you want to get new hands engaged and interested.  On the other hand, if you want something to be done right the first time, do it yourself!  At the Ohio State Mansfield sugarbush, I am constantly balancing the need to get volunteers into the woods while still maintaining standards of quality and efficiency.  Here are a few tips that we use to make sure our volunteers are a help and not a hinderance.  Hopefully you can use one or more of these ideas to streamline your own efforts to reach this delicate balance.

Precision tappers are expensive, but precision tappers are also efficient and effective at controlling the single most important activity in your woods – tapping!  Precision tappers allow you to set the exact tapping depth and reliably expect that the grip points on the end of the device will result in a steady straight taphole each and every time.  While they are costly, our taphole consistently went through the roof when we employed these this sap season for the first time ever.  Precision tappers are probably not for the average producer, but if education and outreach is a central part of your mission, they may well be worth the cost.

An extra step for ensuring excellent tapping is to clearly mark your tapholes at season’s end with a dot of forestry paint.  If you are employing geometric tapping (e.g, over 3 inches-up 6 inches, over 3 inches-down 6 inches, …), then next year’s instructions simply become “find the [insert color of your choice] dot, space over, and tap.”

While we are on the subject of tapping, choose a sacrificial tree to train your tapping crew.  This double-trunked specimen is below our sap shed, has half its crown busted out, and has been tapped no fewer than 100 times in the past 5 years.  Our sacrificial tree is a classic “take one for the team” scenario.  Drilling a good taphole is only part of proper tapping.  How to properly set the spout is just as important, and in my experience, more apt for abuse and mistakes.  Repetition with back-and-forth feedback are minutes worth their weight in gold if volunteers or new help tap a significant portion of your woods.  Make your mistakes here – not on your production trees.

Lead by example in the sanitation department.  If your sap tank is filthy and scummed over, it’s hard to expect your help to take you seriously about sanitation in the rest of the woods.  If your tapping gear is mud-caked and filthy, it’s probably a bit hypocritical to expect your volunteer crew to keep your gear spotless and spit-shined.  Be diligent about sanitation, speak often about sanitation, and your help will take sanitation seriously as well.

Keep a volunteer’s job simple but always give them a roll of flagging tape to pinpoint potential issues they may run across.  If they see something suspect, have them tie up some flagging tape so you can check it out later.  Better yet, and particularly useful for keeping track of progress and directions in the woods, if you incorporate some numbering system into your main lines and laterals.  Below you’ll see an aluminum write-on tag that we tie on each lateral loop starting with main line number and ending with lateral line number.  So in this case, you’re looking at the 3rd lateral line on main line #1.  Navigation and giving directions becomes exponentially easier with this numbering system in place.

While we are talking about lateral loops, show your volunteers the rapid visual checks a producer has to ensure their woods are working properly.  As volunteers walk the woods, it’s easy to visually confirm that sap is traveling around the loops signaling a functioning system.  The same goes for sap flow through the drops into the laterals.  If the loops or drops are empty but the rest of the woods is running good, a strip of flagging tape might be warranted.

And lastly, do not realistically expect perfection.  I found this double spout tree untapped just last week.  It’s too bad we didn’t get this one tapped earlier, but if 1 big tree’s production is the price I pay to get someone excited about maple – that’s a price I suppose I’m willing to pay.

Fall Maple Assessment – Get Ready for Next Season

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The leaves have changed and have mostly fallen from the trees.  In some corners of Ohio, the first snow has already fallen.  For maple syrup producers, that means the push to get ready for a new season is upon us.  This is the best time of year to walk through your entire operation and systematically appraise your operation.  Now is the time to walk your sugarbush with a notebook in hand.  This assessment process allows you to locate the little things that make a big difference when the sap starts flowing.

Begin by looking at the most logical place first – your trees!  What condition are the trees in?  Are they healthy?  Did the June storms cause wind damage to the crowns?  The health of the trees will determine the number of taps per tree, and to some extent, the depth of your taphole.  If trees appear stressed, consider tapping a bit shallower (1.5 inches) rather than the full 1.75” or 2” depth.  It is not unusual to rest a tree for a season, allowing it to overcome obvious stressors.

Now reflect on your tubing system’s performance the very first year it was installed.   Compare that year to the way your system performed last year.  Have you noticed a drop-off in performance? It is easy to blame a poor season on the weather; in reality, the cause could be the age of your system and some neglected repairs.  For many producers, the first inclination is run out into the woods looking for squirrel chews and start repairing lines.  Do not get me wrong, that is important, but it is just one stage of a more holistic leak detection process.  The first order of business should be to inspect the lines for more systemic degradation and disrepair.  I hope that everyone is starting every season with all new spouts?!  However, your assessment should look deeper still.

When was the last time you changed the drops?  How long are the drops?  Are they long enough to allow you to reach around the tree?  Thirty-two inches is a good starting point for drop length in established systems.  What condition are your tees in?  Bad tees lead to micro leaks that sometimes are worse than squirrel chews because they are harder to locate and might be ignored an entire season.  What condition are your laterals?  Do they need to be replaced?  Are you noticing a mold buildup in the lines?  Are your lines patched together because of multiple repairs and damage?  When you replace laterals, it is a good time to look at the overall layout of the lateral system?  Count your taps on each lateral to determine if one is overloaded.  Remember, any given lateral should only be carrying 5 to 7 taps.  Also look at the slope of each lateral.  Is it running straight and tight and downhill for best performance?  What about your saddles, are they leaking?  Old saddles, just like old tees, need to be replaced on a regular basis – at least every 5 years.  Old saddles are often one of the major causes of leakage in maple tubing systems.

The next area of concern is the mainlines.  Ultraviolet light and wind damage are major causes of stress on mainlines.  Mainlines are good for 10 to 15 years, but eventually they must be replaced.  Yes, that is an expensive project!  However, the benefits outweigh the cost.  Installing new lines also allows you to remove damaged and unwanted trees during the repair.  Sugarbush stand improvement is important as it will improve the overall health and productivity of your sugarbush in the long-term.  Hazard trees, such as standing dead ash, should also be dealt with during a mainline replacement project.

It is easy to see how performing a pre-season assessment of your tubing system can be beneficial.  And that is just the tubing system!  After you walk your sugarbush – clipboard in hand – go back to the sugarhouse and develop an improvement plan. What must you buy?  In what quantity?  When will it arrive?  Are their supply chain delays?  Rank everything you have found in order of importance and start chipping away at your list – sap season will be here before you know it!

Ohio Maple Boot Camp

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We hosted Maple Boot Camp at Ohio State Mansfield on June 22-24.  Carri Jagger, Thomas deHaas, and Kathy Smith pulled this post together for the Buckeye Yard & Garden Online blog.

We cannot hold events of this quality without a lot of help and support.  A big thanks to Carri and Kathy, Mike Lynch from CDL, Mike Hogan of OSU Extension, Sayeed Mehmood, Les Ober, Mike Rechlin, Kate Fotos, and Mike Lucero.  I hope I am not forgetting anyone.  And an especially huge thanks to the Brown family at Bonhomie Acres and Stan Hess for opening up their operations for tours and interfacing with Boot Camp attendees.

Here are a sprinkling of photos to supplement what you’ll see at the linked write-up above.

UVM Proctor Red Maple Research

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There is plenty to learn from this video focused on Proctor’s red maple research.  How much sap is produced?  How sweet is the sap?  What sort of quality can be achieved with the syrup?  This research has a similar set of questions to the USDA ACER grant we are working on here in Ohio comparing sugar maples to the red x silver hybrids on The Ohio State University-Mansfield campus.

Sap Yields: Why CODIT and Non-Conductive Wood Matter

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CODIT stands for Compartmentalization of Decay in Trees, and sugar maples are darn good at CODIT!  Mark Isselhardt, during the 2021 virtual Ohio Society of American Foresters spring meeting, gave an excellent microscopic and physiological explanation of how maple trees wall off and seal up old tapholes.

Why does understanding compartmentalization matter to a maple producer?  Compartmentalization creates the all-important non-conductive wood that sugarmakers try to avoid with each year’s new taphole.  And just in case you were wondering – how much does it matter?  Through work conducted at University of Vermont’s Proctor Maple Research Center, Mark Isselhardt document sap yield declines of 70-75% when a taphole intersects non-conductive wood.

Ohio Maple Days 2021 Presentations AVAILABLE

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Despite being virtual due to COVID-19, 2021 Ohio Maple Days – or more accurately Ohio Maple Day sans the “s” – was a success.  The audience, two hundred or so strong, heard presentations on tapping and updates from our ACER grants in addition to how production might be increased with red maple.  A big thanks to this year’s speakers and an extra round of applause for the committee who worked hard on an event that looked quite a bit different than in years past.  One silver lining to having a virtual event is that the sessions are easily recorded.

Visit the Ohio Woodland Stewards Maple page and scroll to the bottom of that webpage to access the different presentations.  Let us know what you think and send us any questions, comments, concerns, or suggestions to talk topics for next year!

Optimizing the Performance of My Vacuum Tubing System, Part III

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The goal of the previous two articles (Part I, Part II) and this final installment is for you to realize that there are many factors that go into installing and running a maple vacuum tubing system. All the factors are interrelated and each one needs to be careful considered on the part of the operator.  The below information is contained in the Cornell New York State Tubing and Vacuum System Notebook (NSTVN) written by Cornell University’s Maple Specialist Steve Childs.  Much of the information is these three posts is a synthesis of past content with some more recent best practice guidance.

Part I introduced basic concepts of vacuum in a tubing system, some different variants within vacuum systems, and the different factors (most well within the control of the producer!) that influence vacuum levels throughout a system.  Part II walked you through how to calculate vacuum levels within your system and how to ensure your production needs are met by your system’s capacity.  The final installment will help direct you towards a vacuum pump that will do the job you need it to do.

 

When someone brings up the subject of vacuum, one of the first questions producers ask is, “What size vacuum pump will I need to run my system?” They will also sometimes ask, “Will the old rotary vane pump my grandfather abandoned in the barn 10 years ago (or longer…) do the job?” The question I also ask back is this, “What vacuum level do you want to run at today and into the future?”

We should get the second question out of the way first. Grandpa’s pump was designed to milk cows, and Bessy would get a little fussy if the vacuum level were to jump above 15 Hg. So the simple answer is that Grandpa’s pump will work, but it is not designed for optimizing maple production. But if you are happy with a modest increase in production beyond simple gravity-fed lines, dust off the old rotary vane pump and run it at the recommended RPM. Moving on to where the maple industry has evolved.

To review, vacuum pumps are designed to remove air from the system, and we already know that vacuum pumps are rated in terms of their ability to remove cubic feet per minute (CFM) from the system. Two additional factors come into play when comparing vacuum pumps. One is the horsepower rating, or the power required to remove air at high levels of vacuum. As the air is removed from an enclosed area the molecules of air in that area become very sparse. A pump must work very hard to remove the remaining molecules of air in the system. The pump must also overcome the force of the negative pressure inside that enclosed area, and this challenge requires more horsepower. A larger pump with a higher CFM rating has a higher capacity to accomplish this task but bigger pumps also require higher horsepower motors. The final factor is pump speed. If you turn a pump faster your will move more air thereby increasing the pump’s capacity. However, over-speeding a pump can cause excessive wear on the pump. This becomes a critical factor when sizing a gasoline of diesel motor driven pump. Pullies need to be sized correctly or performance is sacrificed.

Caption: Vacuum gauge measuring 26+ inches of vacuum

Most of today’s liquid ring, flood vacuum, rotary claw and new age rotary vane pumps are designed to run at vacuum levels up to 29 inches. An important thing to remember is that all pump ratings and vacuum level capacities are preformed using a standard test at the factory removing air from a sealed vessel and a performance curve is developed. This is done in a controlled environment. Now the question becomes what happens when you lower the air temperature and increase or decrease the barometric pressure? The result is confusion. Today, many maple equipment companies are simply listing pump sizes by motor horsepower instead of by CFM capacity. I have personally never seen optimum conditions out in a sugarbush in February and March, and as pointed out above, motor horsepower is only one factor determining pump capacity.

Another question I have is this – “What is the likelihood of that pump reaching 29 inches of vacuum in your sugarbush?” How many times have you heard producers tell you that the pump gauge mounted somewhere near the inlet of the pump is reading 28 inches of vacuum and therefore he must be producing 28 inches of vacuum at every tap in his woods? The harsh reality is that out in the woods he might be struggling to produce 15-20 inches of vacuum. What has the producer not factored in? First, line loss because line diameter can be restricting flow and impairing the ability of the vacuum pump to remove all the air from the system. Second, the producer might have an abundance of leaks in his or her system. The reality is that the only vacuum reading that counts is the reading that is taken out in the woods at the last tap. Today in the age of maple tubing system monitors, producers can know exactly what level of vacuum they have at the end of each line. They can also monitor the level of vacuum at the releaser and make the comparison to the end of their lines and isolate and correct problems as they occur.

To determine what sized pump your operation requires, you should begin by constructing an evaluation like the one used in the NY State Maple Tubing and Vacuum System Notebook. Start by calculating the proper line size for the number of taps you have now and do not forget to think ahead regarding possible expansions you may make in the future. Factor in your equipment such as the releaser you want to run, whether you have lifts in your system and other CFM consuming features. Do not forget to build in some reserve performance to allow for possible leaks and for keeping up with your during peak runs. At this point, you should have a good idea of the right-sized pump for your operation. If you are right on the edge of meeting CFM demand, you should strongly consider buying a pump one size or even two sizes bigger than you planned especially if expansion is in your future. What’s the old adage? Buy once, cry once.

The Bottom Line

You have now made all the calculations and are beginning to understand the logic and principles behind setting up a vacuum tubing system. So what is the return on investment (ROI) for spending money on a bigger pump and increasing the size of your lines? For that answer, let’s look at yield research done at UVM Proctor Research Center. For the UVM study, the goal was to determine yields in systems up to 25 inches of vacuum. The results showed that sap yield doubles when vacuum is taken from 0 to 15 inches (8 gallons per tap). From 15 to 20 inches, the payoff was a 3 gallon increase, and pushing vacuum another 5 inches to 25 Hg resulted in an additional 2.5 gallons. At 25 inches vacuum, you have added nearly 14 gallons of sap per tap.  Even at 20 inches of vacuum, the additional yield is still over 10 gallons. In today’s market you can add a modern vacuum pump, a releaser, and moisture trap for less that $10,000. If you increased your production by 75% on 1000 taps, you would go from 250 gallons a year to 400. If those 150 extra gallons sold on the retail market for $50.00, your return would be $7,500 dollars. At that rate, you have paid for your vacuum upgrade in two years. What are you waiting for?!

This is the final installment in the 3-part series dedicated to optimizing your vacuum tubing system.  Be sure to leave questions or comment below.

Author: Les Ober, Geauga County OSU Extension

Optimizing the Performance of My Vacuum Tubing System, Part II

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The goal of the previous article (Part I), this article, and the next is for you to realize that there are many factors that go into installing and running a maple vacuum tubing system. All the factors are interrelated and each one needs to be careful considered on the part of the operator.  The below information is contained in the Cornell New York State Tubing and Vacuum System Notebook (NSTVN) written by Cornell University’s Maple Specialist Steve Childs.  Much of the information is these three posts is a synthesis of past content with some more recent best practice guidance.

Part I introduced basic concepts of vacuum in a tubing system, some different variants within vacuum systems, and the different factors (most well within the control of the producer!) that influence vacuum levels throughout a system.  Part II will walk you through how to calculate vacuum levels within your system and how to ensure your production needs are met by your system’s capacity.

It is not uncommon during a peak or flood run for your vacuum to drop. If you maintain your lines and are running a tight, leak free system what is the possible explanation for this sudden drop in vacuum? One possible reason is CFM Allocation (air flow measured in Cubic Feet per Minute). In the most basic systems, all vacuum lines are properly and equally sized with the same number of taps per line and all running to a single collection point. The CFM requirements to maintain optimum vacuum will be equally distributed across the whole system. For example, if you have 4 lines of equal diameter connected to a 60 CFM vacuum pump each line would receive 25% of the vacuum CFM (15 CFM). According to theory that would be enough vacuum to run 1500 taps on each line. To use another example, if you are using a 20 CFM pump on a system with 4 equally sized lines and each line serviced 200 taps each for a total of 800, then you would be allocating slightly less than 5 CFM to each line – still more than enough to run each line. However, Total CFM utilization is not always dictated by the number of taps in the woods. One must account for the CFMs utilized by other components of the system, such as if you run a mechanical releaser and other add-on features like lifts or reverse-slope releasers. This reduces the number of available CFMs to accommodate tree loss and leak loss.

Caption: Vacuum Pump with Vacuum Gauge

Now let’s add some complexity to our scenario. Let’s say you expand your 800 tap operation by adding 600 taps to the backside of one of your 200 tap lines. What happens to your 20 available CFMs if you remove a 1” line and replace it with a 1 ¼” line to service the line that now has 800 taps. Now you have 3, 1” lines and the new 1 ¼” line servicing 1400 total taps.  Now you must calculate your line allocation to determine proper CFM distribution.

The first step is to calculate the cross-sectional area of each pipe which is easily accomplished with basic geometry’s “area of a circle” equation.

Cross-sectional Area of a Pipe
Diameter Area
¾” 0.44 in2
1” 0.78 in2
1 ¼” 1.23 in2
1 ½” 1.77 in2
2” 3.14 in2
3” 7.07 in2

Second, you need to determine the percentage of your total vacuum going to each line.  As a reminder, our example has 4 mainlines: 3, 1” lines and a single 1 ¼” line.  Here is a simple way to determine vacuum distribution.

The cumulative cross-sectional area of our 3, 1” lines = 0.78 + 0.78 + 0.78 = 2.34 square inches.  And for the single 1 ¼” line, 1.23 square inches.  The grand total sums to 3.57 in2.

Now divide the cross-sectional area of each line by the total to see what proportion or percentage of vacuum is being applied to each line.  You will find that each 1” line is pulling 22% of your overall CFMs which leaves 34% of the vacuum for the 1 ¼” line.  By CFMs (remember you started with 20 CFMs), each 1” mainline is pulling a maximum of 4.4 CFM and the single larger line is hovering just under 7.

You can quickly see that you are sending way too many CFMs to each of the 1” lines and not enough to maintain good vacuum on the 1 ¼” line.  A quick solution would be to combine the 3, 1” lines into a 1 ¼” manifold with the existing 1 ¼” line going directly into the releaser. That would result in the releaser with just two lines coming out each equally sized at 1 ¼”. This solution would re-allocate 50% of the CFMs to each line solving the problem of line allocation.

It is important to remember, you need to account for leaks that will introduce more air into lines. You might be able to maintain peak vacuum on most average days, but will your system  keep up with sap flow when the big run hits and you need to move as much air as fast as possible to maintain vacuum levels. If you have your lines sized properly, you now need to take the next step to determine what size pump you should purchase.

Stay tuned for Part III (What Pump to Purchase?) on Thursday and be sure to leave questions or comments!

Author: Les Ober, Geauga County OSU Extension

Optimizing the Performance of My Vacuum Tubing System: Part I

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The goal of these next 3 articles is for you to realize that there are many factors that go into installing and running a maple vacuum tubing system. All the factors are interrelated and each one needs to be careful considered on the part of the operator.  The below information is contained in the Cornell New York State Tubing and Vacuum System Notebook (NSTVN) written by Cornell University’s Maple Specialist Steve Childs.  Much of the information is this and the next two posts is a synthesis of past content with some more recent best practice guidance.

When we talk about tubing systems, we have two roads to travel. One is a gravity system and the other is a vacuum system. A conventional 5/16” gravity system is not much different from running sap into a bucket. The yield is much the same as collecting sap in a bucket. When we add vacuum to a tubing system, we increase the sap yield 5% for every inch of vacuum we generate in our system. For example, if we produce 15 inches of vacuum in a line, we should be able to almost double our sap yield.  The first year after installation is always the best. As time on a system accumulates, wear-and-tear hampers performance.

Caption: Year 1 Production with a Brand-New System Should Provide Your Best Vacuum Levels

The definition of vacuum is the absence of air. The maximum level of vacuum achievable on any given day is determined by the barometric pressure. This means that our vacuum level can never exceed the barometric pressure in the location of our sugar bush. There are two way to measure vacuum pump performance, Inches of Mercury (hg) and Cubic Feet per Minute (CFM). Inches of mercury measures the negative pressure produced when air leaves the line. For example, if 50% of the air is removed then the inches of mercury should be somewhere between 14 and 15. At 25 inches of mercury, approximately 85% of the air has been removed from the lines. CFM on the other hand measures the amount of air being evacuated from the lines in units of cubic feet per minute. This is the amount of air that a vacuum pump is pulling out of the system in one minute’s time. Where is the air coming from? The answer is gas that is forming inside the tree and being expelled through the tap hole. As a rule of thumb, there is a 1 CFM requirement for every 100 taps on the line.  However, the biggest contributors are leaks allowing air to enter the system through damaged or aging tubing. This statement emphasizes the importance of managing leaks in a vacuum tubing system.

Caption: Vacuum Gauge Measuring Vacuum in Inches of Mercury (hg)

Speaking of leaks, the most important part of operating any maple syrup system is the time you spend in the woods making sure your vacuum tubing system is leak-free. Much of the rest of the article is spent discussing different technologies and equipment, but the simple fact of the matter is this – the best equipment with poor care in the woods won’t do you a lick of good when it comes to putting more maple syrup on tables of your customers. You must always account for leaks that introduce air into lines. You might be able to maintain peak vacuum on average days, but your system will show its weak points when sap flows are running fast and you need to move as much as air as fast as possible to maintain vacuum levels. Being able to spot and repair leaks quickly is essential. To accomplish this, you should design your system so you can isolate lines to pinpoint problems. This can be done by compartmentalizing your system with valves and vacuum gauges placed at the starting point of each line. The installation of a tubing monitoring system can be a wise investment as well, and the time saved and extra sap produced will pay for the cost of the upgrades in short order.

Back to our lesson on vacuum and barometric pressure. There are factors that have a direct effect on barometric pressure. One is altitude. As the altitude increases the maximum barometric pressure declines (rule of thumb: for every 1000 feet of elevation you lose 1 inch of vacuum). For example, at sea level, or 0 altitude, the average barometric press can be 29 inches; at 2000 feet, the average maximum barometric pressure obtainable is only around 28 inches. In addition, barometric pressure changes under different environmental conditions, and variations in barometric pressure caused by atmospheric changes can occur multiple times in a day. If we are running a vacuum pump under a low barometer at 2000 feet elevation, we might struggle to maintain 28 or even 27 inches of vacuum on a very tight well-maintained tubing system.

Sap moves down the line by gravity on a system of tubes suspended with wire. The basic components are spouts, tees, and drops moving sap from the tree into lateral lines. A lateral line should have no more than 5 to 10 taps per line and should be no longer than 100 feet in length. The lateral lines flow into main lines. In large systems, secondary mains flow into Wet-Dry lines and or trunk lines (large diameter lines) that move the sap to a central collection point.   To properly function, sap lines should be straight, pulled tight, and sloped downhill. To this point gravity systems and vacuum systems are similar, with the gravity system relying on slope and Newton’s law of gravity to move the sap.

Caption: 65 CFM Bush R-5 Vacuum Pump

When vacuum is added to the system, sap flow is aided by the movement of air.  The components of a vacuum tubing system are the vacuum pump, which is connected to lines via a sap releaser. Even though it is called a vacuum pump, it is not a pump in the conventional sense of the word and that is a bit confusing. A conventional pump moves liquid creating pressure ahead of the liquid and suction on the backside of the liquid. There are other types of pumps used in maple production. For example, a diaphragm pump is a conventional pump and that creates enough suction (secondary vacuum) to draw sap from a tree. However, if liquid is not present in the lines that suction can be lost.  A true vacuum pump moves air, not liquid and it creates a higher level of vacuum (absence of air) as the air is removed from the lines. That level of vacuum can be maintained with or without sap in the lines and will only drop if a leak allows outside air to enter the line.  Because the pump is designed to move only air, the liquid must be separated from the pump. This separation process is performed by a sap releaser. If sap enters the vacuum pump severe damage to the pump can occur! To prevent this from happening, a moisture trap is placed between the pump and the releaser.

Caption: Sap house releaser (right) with Vacuum Piston Pump (left)

A properly sized vacuum pump with a proper CFM rating will be capable of removing air faster than it is introduced. However, there is one factor that can interrupt and slow that process – line size. Vacuum lines are designed to conduct air to the pump. If your line diameter is too small, the air movement will be restricted requiring more time for the pump to clear air from the lines. This phenomenon is referred to as line loss. The smaller the line the more the air flow is restricted resulting in higher line loss. As an example, a 60 CFM pump set at 15 inches of vacuum hooked to a 3“ line can maintain over 40 CFM out to 5000 feet. However, that same pump hooked to a ¾” inch line is incapable of delivering 15 inches of vacuum at 2500 feet from the pump. Line loss increases the time (recovery time) needed to evacuate air from the line and restore peak vacuum level.

What is missing from this equation? The capacity of the line to conduct liquid. Every diameter of pipe has a maximum liquid capacity. The size of the pipe that is needed is determined by the number of taps flowing into the pipe. Each tap during a peak flow might contribute upwards of 0.2 gallons of sap per hour. Once you calculate the amount of sap flowing in you can determine the size of the pipe that is needed. There is however one caveat, the steeper the slope the faster the sap moves through the line thereby effectively increasing the capacity of a given-sized line on steeper slopes. Slope can also influence sap flow in other ways. The portion of the line, 50 feet or longer with the least amount of slope, will strongly influence sap flow. Examining this critical portion of your line might dictate a necessary increase in line diameter to allow for adequate air and liquid flow. Remember, you need to move air as well as liquid through a maple pipeline. To do this you must maintain the proper ratio of air to liquid inside the line so as not to inhibit sap movement. If you look at a working cross section of tubing it should contain 60% air and 40% liquid. This is a primary consideration when determining what size of line to use in your sugarbush.  If the liquid level increases beyond that ratio or is uneven (wavy), the air movement will be restricted resulting in a drop in vacuum.

Caption: Whip Connection to a Wet-Dry Line.

There are two ways to solve this problem. The first would be to increase the size of your main lines but 1 ½” inch and 2” tubing is expensive, and it adds to the overall expense of the tubing system. Still, increasing tubing size may be justified if you have a large number of taps coming into a trunk line. The other alternative is to install a dual-line conductor commonly known as a Wet-Dry Line. Composed of two lines of equal size (or a dry line slightly larger than the wet line), a Wet-Dry system can excel at moving sap across flat areas or areas where multiple secondary mainlines merge. Secondary mains may enter the Wet-Dry line at a booster, or a line configuration called a whip. This allows sap to move down the wet line without impeding the airflow in the dry line. This set-up is particularly useful in flat areas where slope in minimal and sap flows slowly which may inhibit the necessary amount of air flow. Wet-Dry lines can be a cost-effective way to move sap through areas of minimal slope.

Stay tuned for Part II in a couple of days and be sure to leave questions or comments!

Author: Les Ober, Geauga County OSU Extension

Handling Sap and Syrup During the Season

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The maple season is now underway and this is a good time to talk about handling your sap during and after collection. How you handle your sap prior to boiling will strongly affect the quality of the syrup you make. When quality syrup is the goal, timing is everything, and the clock starts as soon as the sap leaves the tree and doesn’t stop until it hits the evaporator.

When sap comes from the tree, it is sterile. That all changes once the sap starts to drain from the taphole. The air and surfaces surrounding the tap contain an abundance of microbes. The sap supplies the food source and a media for the microbes to grow and multiply. Research at Center Acer in Quebec found 21 different strains of microbes present in sap. At first you would think that could be problematic, but the reality is, you need certain strains of bacteria to produce the color and flavor that is unique to maple syrup. For microbial growth you also need the right temperature. Once the environment warms the sap, microbes multiply rapidly. Producers can monitor the potential for microbial growth by checking the temperature of sap. If the temperature is close to freezing, growth is suppressed. Below 40 degrees Fahrenheit, the growth of bacteria is slow, but once the temperature rises above 50 Fahrenheit microbial growth is rapid. The chances for 50 degrees and above temperatures are greatest at the end of the season.

When sap leaves the tree, the sugar is 100% sucrose. Once the sap is exposed to bacterial action, a small fraction of the sucrose is converted into glucose and fructose, often referred to as “invert sugars.” When maple sap containing sucrose, glucose, and fructose is heated, you create an amber color and a unique maple flavor. The problem is when undesirable bacteria begins to outnumber the good bacteria. This changes the chemistry of the sap. As the invert sugar level increases, syrup begins to take on a darker color and a stronger maple flavor. This produces the different grades of syrup. Syrup early in the season has a light color and very mild flavor. The maple syrup produced at the end of the season is often darker and stronger flavor. Syrup containing higher levels of bacteria can develop a very strong almost bitter off-taste known as sour syrup. The syrup consistency takes on a thick almost rubber like appearance and is often referred to as ropey syrup. Sour sap is often confused with buddy syrup because it happens most often at the end of the season. Buddy syrup is caused by sap coming from trees where the buds are getting ready to bloom. The chemistry is completely different from sour sap. Sour sap can happen any time during the season when a warm spell causes extreme flushes of bacteria growth. Sour sap can be prevented with good sanitation practices. Buddy syrup is a natural occurrence every year at the end of the season.

The quality of syrup produced from buckets and bags is best early in the season. Once the hole is drilled and the spout is exposed to the air, microbial development and taphole healing begins. Your season has begun, and you are now on the clock. A normal season for a bucket, bag or gravity tubing producer is 4 to 6 weeks. During the cold periods early in the season, the sap stays fresh just like it would if you put it in your refrigerator. Keep your sap below 40 degrees Fahrenheit and you are fine, but let it heat up to over 50 degrees and you asking for trouble. That happens readily at the end of the season. What many producers forget is that the bucket is an incubator for bacteria if it is not cleaned out regularly throughout the season. Leaving sap sit in a dirty bucket for any length of time is a problem. Remember bacteria does not grow in a clean dry bucket. If you are in a warm spell wash out your buckets and place them upside down next to the tree. If you are in a extended cold period, you should collect your buckets and let them hang until the next run. And never let stale sap sit a bucket, hot or cold.

As for tubing, we have discussed tubing sanitation multiple times over the years and those articles are in the Ohio Maple Blog Archive. Keep your lines as clean as possible throughout the season. This is difficult unless you are on continuous high vacuum. I know it sounds expensive to run the pumps 24/7, but it works to your advantage by keeping the lines cool and dry when the sap is not running. Another essential is to follow the tubing sanitation guidelines, installing new spouts every year, and new tees and drops every three years. You will improve the quality of your syrup.

Once you get the sap to sugarhouse, there are additional things you can do to improve quality. Sap that is going to be stored for longer periods of time needs to be stored in a stainless steel tank. Avoid poly tanks for sap storage. Plastic tanks are incubators for bacteria. Older galvanized tanks, like galvanized buckets, need to be discarded because of the risk of lead contamination. For the backyard producer, make sure your tank is in the shade. Pack around it with snow if possible. You can even freeze some sap and put it in the tank during warm spells. What ever it takes to keep your sap cold, take those necessary precautions. Anytime your sap reaches 50 degrees Fahrenheit and you can’t immediately cool it back down, boil immediately.

What about the evaporator? Boil your sap as quickly as possible. If you are using a reverse osmosis machine, make sure you do not let your concentrate sit. Boil it as soon as it comes through the RO. You double, triple, and in some cases, quadruple the sugar concentration in your sap, and bacteria builds fast in concentrated sap. If you are using a small evaporator, it is a good idea to drain and flush your rig. Leaving partially boiled sap on an evaporator in a warm sugarhouse can result in ropey syrup. Once the syrup is filtered get it into a barrel or a container as fast you can. Do not let it sit around. Pack your drums hot and do not open them until you are ready to use them. Do not store syrup drums in a warm building. Move them into the basement where it is cool or package the syrup at 185 degrees Fahrenheit shortly after the season. From the tree to final container, paying attention to details pays big dividends.

Author: Les Ober, Geauga County OSU Extension