Category Archives: Maple Education
Les Ober OSU Extension
I got up this morning and it was 60 degrees. All I could think of was that a lot of my friends who make maple syrup got up, saw the same thing I did and headed straight to the sugarhouse to find their drills. To say the least this is unusually warm for this time of year and it has everyone scratching their head. I also looked at the internet and questions were coming into the OMB about whether it is time to tap. This is topic that will be address in depth at the Ohio Maple Days but due to the early warmup I will give you my take on the subject.
First a little science! To quote New York Maple Specialist Steve Childs we need to know “How Does Sap Happen”. Sap flow is the result of sap rising and falling in the tree through the vascular system of a maple tree known as sapwood. The sap flows to provide nutrients to all of the vegetative growth above ground. Sap flow from the roots to very tips of the branches nourishing the buds that will develop into leaves. This process is on a phonological clock that limits the amount of time that we have to intercept a very small portion of that sap and make it into maple syrup. Once the buds emerge the sap is no longer useable for syrup production. Sap rises because of a variation in spring temperatures that we call the freeze thaw cycle. The tree freezes, this creates a suction that draws nutrients from the roots along with ground water. Once the temperature rises above 32 degrees F, gases begin to form inside the tree. This pushes the sap up the sapwood the tree up into the very tops of the branches. Considerable pressure is produced in the process. In fact that pressure can reach 40 psi. When you drill a hole in the tree sap leaks out into a bucket and continues until the tree quits pushing sap or it freezes again. We can increase that flow by applying vacuum to the tap with a vacuum pump and tubing. If the temperatures stay warm sap flow will gradually decline. Sap can flow up to 72 hours without the repeat of the freeze thaw cycle. Without freezing the sap level in the tree drop below the taphole and the flow will stop. Once the temperatures drop below freezing the whole cycle starts again. This is a very simple explanation of a very complex process.
What else can cause sap to stop flowing from a taphole? Once a taphole is drilled into a tree the maple season clock starts to run. With buckets and open tap holes that window of opportunity is around 4 weeks before the taphole starts to heal up and the sap flow stops. This healing is the result of the taphole being exposed to air and from the growth of bacteria in and around the hole. Air dries out he taphole and supplies oxygen to bacteria that coat the hole with slime that eventually seals off the exposed sap wood. Similar to what happens when you get a cut. Blood flows for a while but eventually it coagulates and the bleeding stops. A vacuum tubing system is different in that the taphole is not exposed directly to the outside air and sap is kept flowing under vacuum for a longer period of time. If operated correctly the hole will be kept free of bacteria for most of the season. This can be accomplished two ways. First you can keep the vacuum running continuously whenever the air temperature is above freezing. This will keep the sap moving keeping the lines clear and the taphole cool. Producers have found that they will gather enough sap during extended warm periods and make enough syrup to pay for the cost of running the pumps during that period of time. The other method is to us a vacuum system with check valves to prevent bacteria laden sap from the lines being pulled back in the tree. A tree will draw sap from the lines just like a hose will siphon water from a tank when you turn the tap off. This bacteria laden sap will aid in healing and shutting down the taphole for the season. The check valve will close when the vacuum is released and it will seal off the tap. I discussed many of these taphole sanitation techniques along with the use of check valves in an earlier post on this blog. A side note; for those of you using a 3/16 gravity system, research at the Cornell Maple Program, shows that because you are generating a higher level of vacuum a pull back into the tree occurs. Preliminary research shows that using a check valve will increase the yield in a 3/16 tubing gravity system. I intend to discuss 3/16 tubing in an article to be published on the OMB at a later date.
Now to answer the question should I tap or not tap during and early warms spell. My suggestion is to obtain all the information you can about upcoming weather patterns. Then look at your system. If you are a small producer or a backyard producer looking for the ideal 30 day window, January is most likely too early to tap. Your taps may dry out and you may miss some of the really good runs in late February or March. You could re-tap but that is hard on the tree and is never recommended. The best approach is to watch the weather and be ready to get those good runs in February and March. For those of us who have vacuum tubing. We can stretch the season with taphole sanitation techniques. Watch the weather and tap when to opportunity arises. You may get some very good early runs. If you are going to tap now make sure you change out your spouts or use check valves. You have to create a closed system at the tree to prevent taphole healing. If you have enough taps consider tapping the side of the woods that runs early now and the late running sections later on, spread the season. The best you can hope for is two months before your taps start to shut down. I have personally kept my taphole open from the 10th of February to the 10th of April with the use of check valves and continuous vacuum operation. No matter what you decide to do it is a gamble, here’s hoping your decisions pays off. Here is a little additional information that may help to make you decide. NOAA Weather has now released their 3 month forecast for January, February and March. It is now calling for above normal temperatures during the period for Ohio into New England. I will hedge a little but my taps will be in by February 1st.
Geauga County OSU Extension
Two years ago this Fall the maple syrup industry completed the adoption of a new system for grading syrup. It took a long time to get everyone on the same page to complete the process that was officially started in 2011. The International Maple Syrup Institute took the old USDA Standard grades that included USDA Grade A Light, Medium and Dark and Grade B and transformed them into four Grade A categories that would include all saleable syrup. Two important additions were the flavor descriptors and the Tc (light transparency) range. This allows consumers to compare grades on flavor and it also opened the door for the use of instruments in the grading process for color determination.
The four Grade A categories are Golden Delicate, Amber Rich, Dark Robust and Very Dark Strong. You will find that Golden Delicate parallels the old Light Amber Category. Amber Rich includes all of the old medium and the very top of the Grade A Dark Category. Dark Robust includes the rest of the of the Grade A Dark category and the very Top of the old Grade B Category. The Very Dark Strong Category includes the rest of the syrup that was formally classified as cooking syrup. Most very dark syrup that is produced and does not have an off flavor or a density problem will fall in this category. If syrup has an off flavor or does not meet the above minimum of 66 brix, or the below maximum 68.9 brix density standard it will be sold as commercial syrup and priced accordingly. It should be pointed out that the retail price in most markets does not change for any of the top 3 grades and many producers sell their very dark syrup for the same price.
The new grading system allows us to not only sell syrup on color but also on flavor and after all, flavor is what sells maple syrup. Flavor is a component of maple syrup judging that is very subjective. Everyone has their own idea of what maple syrup should taste like. It is almost unfair to put maple syrup in a jug that has not been graded. It would be like labeling a cut of meat as beef. You as a consumer would be buying the package of meat and not know if it was a Porterhouse Steak or Stew Meat. That type of marketing went out the window with the anticipation of finding out what the prize was in a box of Cracker Jacks. Today’s consumers are getting smarter about what they buy. Why would you try to sell them syrup that could be Very Dark Strong, Golden Delicate or something in-between? If you are just putting syrup in a jug you are missing out on an important part of marketing, interrupting and understanding what the consumer truly wants. You maybe marketing high grade of Golden Delicate syrup when the consumers is looking for a darker more robust flavor. The comment you often hear about Golden Delicate is that it is very sweet with little or no maple flavor. If this were case, do you think you will have a return customer; even though you put what you believe is your best product in the container?
There is however, one caution about selling graded maple syrup; it had better be graded right. That is where spectrophotometry comes in. Today for 60 to 80 dollars you can buy a Hanna Checker. There is also a more accurate and expensive model available for commercial packers, contest and grading fanatics. It is all based on the transmission of a beam of light through the sample. As the product darkens the percent light transmission drops. Once you have a reading you match the %Tc light transmission reading on the device to the %Tc range of one of the new grades. Each grade has a % Tc range. The end results are similar but a lot more reliable than a temporary grading kit. Over the last two months putting, together my maple syrup evaluation programs, I have had a chance to look at dozens of samples of maple syrup, some graded and some not. Many times these samples were so close it would be impossible to grade accurately on a hand held temporary grading kit. This new instrumentation makes it easy to grade syrup. This proves once again that maple syrup production is pure science from start to finish.
Generally overall the new grading system has been well received at various locations where we introduced it to the public. At many fairs and shows we have been able to stimulate conversation about the characteristics of each individual grade. Using sample tasting is a great way to interact with your customers. Generally overall potential consumers liked Amber Rich but more and more are trying and enjoying Dark Robust. This has been a learning experience for both the producer and the consumers alike. Ultimately I think many of the producers end up learning a little more about consumer preferences and the product they are selling. Grading in many states is not mandatory and Ohio is one of them. The other factor here is that consumers are really not familiar with how maple syrup is graded. The only thing they can compare it to is your average table syrup which has no identity. This is where maple producers can take a lesson from the wine and craft beer industry. They have built a whole marketing program around identifying the various characteristics of their product. Is it out of the realm of reality that we might someday include a tasting room in our sugarhouses where potential customers could sample the various grades of syrup and other value added products? Think about it, this could add a whole new dimension to the way we market maple syrup.
If you want to learn more about how you can use the new grading system to improve your marketing and your production practices I will be teaching a 4 hour workshop at the Lake Erie Maple Expo on Friday November 11th in Albion Pa. For more information on the workshop contact www.pamaple.org
Ohio State University Extension
This post is in response to the article on maple syrup quality written by Dr. Michael Farrell in the last edition of the Maple News. First let me say that the article was not only excellent but very timely. The article addresses an issue that all of us producing maple syrup need to look at as we start a new seasons production. What I hope to do is highlight some of the areas in the production process where quality can be compromised. These are often identified through off flavors. The University of Vermont and the Vermont Ministry of Agriculture have given us an excellent tool for identifying the sources of off flavors in maple, “The Map of Maple; Off –Flavors”. This was also published in the last edition and is also available from the IMSI publications
After producing maple syrup for over 40 years and teaching seminars on maple syrup production for close to 20 years I have made, and have seen others make, most of the common mistakes that lead to off flavors and poor quality. In this article I will go over some, but certainly not all, of the factors that lead to poor quality. Many of which can be controlled by the producers with proper best management practices. The map of Maple: Off Flavors identifies 5 primary areas where off flavors occur; Mother Nature, defoamer, processing, chemicals and others. I want to address each of these, not in order but how they would occur from the start of the season to the end.
When you start out the season you need to be aware of several problem areas that can lead to off- flavors. Most stems from equipment maintenance after the previous season and going into the new season. When producers and hobbyist ask how I should clean up my equipment, my response is with a lot of water and elbow grease. Anytime we use chemicals to clean equipment we run the risk of leaving behind residues that can compromise flavor. If we use chemicals on our pans to clean them at the end of the season the chemical residue needs to be thoroughly cleaned out. If we store filters make sure there is no mold on those filters when they come out of storage. If you have mold on your filters, throw them out. Never use detergents to clean filters it will alter the flavor. Finally make sure you store your chemicals in a secure place away from the process of making syrup to avoid unintended contamination of your product. Finally if you use a tubing cleaner make sure it is flushed from the system. If you suspect some cleaner may be left in the lines then let part of the first run go to the ground. Most of the above are common sense but they need to be mentioned.
Probably the biggest culprit when it comes to off-flavor is processing. This is where the majority of the mistakes are made that result in off flavors. When we grade syrup we look at 4 primary areas density, color, clarity, and flavor. Even though each is judged separately they are actually all interrelated. Density affects syrup quality in several ways; first syrup must be 66 brix to meet USDA standards and if it is below 66 brix it can ferment and cause an off flavor. Syrup above 67 brix normally does not have an off flavor but the higher density can cause crystallization in the bottom of the container and loss of revenue to the producer. As syrup moves across the front pan the density changes rapidly and so does the color. Density changes occur with the rapid removal of water increasing the sugar concentration. Color changes occur as the sugar molecules change due to the introduction of heat. These changes happen very quickly and need to be monitored closely. Anything that interferes with flow of sap through the evaporator can cause the syrup to get darker and possibly cause an off flavor. Many feel that density is the most critical part of the process and at times reaching the proper density can be very illusive. Improper density management can lead to two off flavors that are very common in syrup; fermented and scorched. It can also lead to an unwanted change in color. The additional boiling time can also affect flavor causing an unnatural taste that is not representative of the grade you are processing.
We use three tools to measure density, the hydrometer, the thermometer and the refractometer. All sugarmakers use a hydrometer. Hydrometers should be inspected or checked for possible problems and replaced if suspect. Often the paper with the scale printed on it can slip resulting in the wrong brix reading. The hydrometer can become coated with film resulting in an inaccurate reading. A good hydrometer will give you an accurate reading only if it is used at the right temperature. Temperatures below that require consulting a chart to get the right brix reading for a specific temperature. Maple syrup boils at 7 degrees above the boiling point of water or 219 degrees. Many producers use a thermometer to determine the draw off point. The only problem is that that the 219 reading is only accurate if the barometer is at 29.9 hg barometric pressure. A thermometer needs to be recalibrated every time the barometric pressure rise or falls. This makes a thermometers reliability somewhat suspect. However, syrup temperature is vital when it comes to setting an automatic draw off. The final tool is what many consider the judge and the jury of maple syrup density, the refractometer. What many producers do not realize is that, for a refractometer to work properly, it needs to read a product that is finished and one that is stable in temperature. This was pointed out the other day, when I had a conversation with Robert Crooks of Marcland Instruments. For a refractometer to work properly it has to be able to refract light coming through the sample it can only do that accurately if the sample in the instrument is a clear finished sample. Taking a sample of cloudy unfiltered syrup can lead to an inaccurate reading. The temperature of the product also affects the light refraction. Even though the refractometer is built to automatically compensate for temperature that temperature needs to be stable. If you leave freshly drawn off syrup set in a container it will continue to evaporate water until it cools down. Think of what happens to a roast when you pull it from the oven, it continues to cook. This is why it is recommended that you cover a container with hot unfiltered syrup to stop the loss of moisture. If you use a refractometer to set the draw off, take the syrup and run it through the filter and collect a sample allowing it to sit for 15 minutes then take your refractometer reading. This will give you the most accurate reading from your refractometer.
If you use a conventional auto draw-off, be aware that it takes time to complete the draw off process. This means that syrup will be drawn off over a range of temperatures. Therefore set the draw off to actuate slightly below the desired temperature and it will finish slightly above. Using a hydrometer is the best way to set your draw off. However, make sure you are reading the hydrometer at the recommended syrup temperature. You can use a refractometer but it has to be used on a finished temperature stable product. This process may take more time than you have to make a correction on the draw-off.
As sap moves across the evaporator temperature gradient sets up. Ninety percent of the water is removed by the time the sap reaches the middle of the front pan. Syrup needs to move from the middle of the syrup pan to the outlet relatively fast. Any interruption with this process that interferes with the temperature gradient and holds the syrup on the pan longer will result in syrup that can be darker and denser than desired. One common mistake is to allow the pans to cool during the firing process. Anytime you cool off the pans the temperature of the sap drops and this causes the boiling temperature to drop resulting in the sap on one side of the gradient to mix with sap on the other gradient. You need to keep a constant heat level on the front pan at all times. This is more critical in a wood fired evaporator.
The other problem is foam control. Excessive foam in the back pan can cause problems with you float and may interfere will your ability to control the level of the sap in the evaporator. If this happens you will need to use a defoamer to control the problem. When using defoamer, the only place the defoamer should be added is at the point where sap enters the rear pan and occasionally a couple of drops if needed, at the draw-off if foam builds up as you are drawing off. This should be done at regular intervals placing the prescribed number of drops (2 drop per foot of width) where the sap enters the evaporator. Never spray defoamer across the front pan to control foam. Using defoamer in this manner will impede the boil and break down the gradient. This can lead to the dreaded big batch. If the front pan is foaming excessively, then the foam is not being properly controlled in the back pan, correct the problem back there. Use only small amounts of defoamer, excessive use can result in an off flavor. Organic producers must use safflower or canola oils which are very poor defoamers. Be careful, using an excessive amount of these products can result in an off flavor.
The other problem that can cause scorching in an evaporator is to allow niter to buildup. When niter buildup it will insulates the bottom of the pan from the liquid creating a potential hot spot which can result in a scorched spot on the pan. You need to keep liquid in contact with the pan at all times. Always keep your pans as niter free as possible by rotating sides or using a clean set of pans. Using a good syrup filtering system to remove niter is vital if you want to produce syrup that meets the clarity standard. You should be able to read newspaper print through a sample bottle of syrup that has been properly filtered. Cloudy syrup with a lot of niter can produce an off-flavor. Remember every time you heat your syrup to a boil more niter will precipitate out and it will need to be re-filtered. That is why you do not want to bring your syrup to a boil when canning. 185 degrees Fahrenheit is the required temperature for canning.
As maple producers we fight the growth of bacteria through our entire system. When bacteria colonies multiply within sap they convert sucrose sugar molecules to Glucose and other invert sugar molecules. This increase in invert sugar, when exposed to heat will cause a darker product. This is most prevalent at the end of the season when the bacterial content of sap is at its highest. Bacteria can affect the entire process of making syrup from the tubing system right through canning. Because sap has a sugar content it is a perfect media for bacterial growth. It goes without saying you can never be too clean when it comes to making syrup. Sap needs to be collected in clean equipment, it need to be kept cool and processed quickly. At the beginning of the season if we start with a properly sanitized system we have few problems with bacteria but as the season progresses the problems increase. Maple Producers need to know when to end the season. Producing syrup late in the season when the trees are near budding and the sap is out of condition has little value to you or the industry. Syrup also needs to be packaged correctly to control bacterial growth in container that can lead to spoilage. That is why we always pack plastic jugs at 185 degrees. This prevents condensation which can supply an environment for bacterial growth in the container.
As you can see there are many areas within the process of making syrup the sugarmaker can have an impact on the quality of the product that is producing. The is attention to detail from equipment sanitation to efficiency of processing is what separates many producers when it comes to product quality. Making the highest quality product possible should be your goal, you reputation as a maple producer depends on it.
Ohio State University Extension
When you bring 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 also ask if the old rotary vane pump their grandfather abandon in the barn is good enough? The question I ask them is; what vacuum level do you want to run at today and into the future. As I stated in Part I there are two way to measure vacuum pump performance, inches of mercury and CFM. Inches of Mercury measure 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 15. At 25 inches of mercury approximately 85% of the air has been removes from the lines. CFM on the other hand measures the amount of air being evacuated from the lines measure in cubic feet per minute. Pumps are rated (CFM) on their ability to remove air and this largely determines the size of the pump. Two other factors come into play when comparing vacuum pumps. One is the horsepower rating. As the air is removed from an enclosed area the molecules of air in that air become very sparse. The pump has to work harder as the air becomes thinner. The pump also has to overcome the force of the negative pressure inside that area. This requires more horsepower. A larger CFM rating does this faster but requires more Hp. The other factor is pump speed. If you turn a pump faster your will move more air and will increase the capacity. However, over speeding a pump can cause excessive wear on the pump. To answer the second question first, Grandpas pump is not designed to produce anything over 15 inches of vacuum and that is not high vacuum. Most of the liquid ring, flood vacuum rotary claw and new age rotary vane pumps are designed to run at vacuum levels up to 29 inches. Remember all of the pump ratings and their ability to increase vacuum level are done at the factory removing air from a sealed vessel. From this information a performance curve is developed. What makes this whole process more confusing is that many maple equipment companies are now listing there pump sizes by motor horsepower instead by CFM capacity. As pointed out motor Hp is only one factor determining pump capacity. When questioned about CFM, one dealer told me his pump will develop 11 cfm at 29 inches of vacuum. This has to be a specification taken off of a performance curve taken at the factory. The question I have how likely is that pump will ever reach 29 in of vacuum in a maple system? The fairest comparison should be made when the CFM is measured on a pump being run at 15 inches of vacuum. Otherwise unless you have performance curve data in hand for every pump you are considering how you can make a fair comparison. Will the pump be able to deliver 29 inches in the woods at a higher elevation, hooked to thousands of feet of line that is anything but leak free?
Are the dealers wrong when they tell you that your pump will produce 29 inches vacuum? The answer that question is yes and no. As stated most pumps are capable and have been tested to deliver 29 inches of vacuum. This is clearly shown on the pump performance curve. However because the performance curve is read at the barometric pressure at sea level an adjustment for elevation above sea level needs to be made. For every 1000 feet of elevation you lose 1 inch of vacuum, this means the highest vacuum level achievable at an altitude of 2000 feet is around 28 inches depending on the barometric reading on any given day. So what is going on when a producer tells you that his pump gauge mounted somewhere nears the inlet of you pump is reading 28 inch of vacuum but out in the woods it is 18 in. or less? Is that wrong? The answer to the second question is no. Because of line diameter is restricting the flow (Line Loss), the vacuum pump has the ability remove all of the air from the system within a short distance of the pump inlet. This phenomenon occurs because the pump can pull air out faster than the line can deliver it, thus creating a small area of high vacuum close to the pump. The gauge at the pump measures only the vacuum in that area. This is graphically displayed in the line loss charts used in the Cornell New York State Tubing and vacuum system notebook. A 60 CFM pump set at 15 hg hooked to a 3 “ line can maintain over 40 CFM out to 5000 feet. That same pump hooked to ¾ inch line is incapable of delivering 15 in. of vacuum at 25 feet. This is covered in a previous post; April 24, 2013 How Can I Get More Vacuum Where I Need it? The pump is only one part of the total system. If the line diameter is too small it will reduce the capacity of the pump to remove air. The reality is that the only vacuum reading that counts is the reading that is taken out in the woods at the last tap.
How do you determine the CFM capacity of the pump that will best fit in your operation? The NY State Tubing Vacuum Notebook (NSTVN) written at Cornell University by State Maple Specialist Steve Childs states that to go from 15 inches to 18 inches of vacuum of vacuum you need to increase the CFM capacity of your system by 50%. You start with the number of taps you have on the system. Let’s say you have 3000 taps. You know that for every 100 taps you need 1 CFM to keep up with the air and gases coming into the system primarily from the trees. This means that it would take a least a 30 CFM pump to remove the air that is coming into the system from the outside. The vacuum level under these conditions would be somewhere around 12 Hg. The NSVTN states that for every 1 in of vacuum you will lose 10% of the capacity of the pump. In order to increase that vacuum level to 18 in or beyond you would need to increase the pump size by at least 50 %. That would mean that you would need a 45 CFM pump. This is only 18 inches of vacuum and you want to produce a high vacuum rate of at least 25 inches. This is based on research done at UVM Proctor Research Center you need to have at least 25 in of vacuum in the lines to get near optimum sap production. However to get to 25 in vacuum you would need to add 7 more inches of vacuum. Starting with a 45 CFM pump running at 18 in of vacuum, using the 10% loss for every 1hg gain you would end up with only 13.5 CFM (4.5 X 7 = 31.5 – 45 = 13.5 CFM). If you go to 75 CFM pump it translates 22.5 CFM (7.5 X 7 = 52.5 – 75 = 22.5), which falls 7.5 CFM short. A 100 CFM pump translates to 30 CFM (10 X 7 = 70 – 100= 30), enough to run the 3000 tap woods at 25 in of vacuum. Again all pumps are not created equal motor size and pump revolution speed come into play. These are just guidelines, some systems are easier to operate than other and it depends on well you manage your system for leaks.
Now let’s look at the yield side, again based on research done at UVM Proctor Research Center. In their study determining the yield up to 25 in of vacuum was their goal. The study shows that sap yield doubles when vacuum is taken from 0 to 15 in. From 0 to 15 in. there was a 8 gal per tap increase, from 15 to 20 in. there was a 3 gal increase and from 20 to 25 in. a 2.5 gallon increase. At 25 in. vacuum you have added 14 gallons of sap per tap. However, at 20 in of vacuum you have added 11 gallons of sap.. So what would happen if you settled for working at a lower vacuum level? If you backed down to 22inches of vacuum a 45 CFM pump would deliver 27 CFM just short of the amount needed. Going up to a 60 CFM pump would deliver 36 CFM, adequate to run the woods with some reserve. You would raise your production by 12 gallons per tap per season. That is 80% of your original goal of 14 gallons per tap.
You have now made all of the calculations and are beginning to understand the logic and principal behind setting up a vacuum tubing system. The one thing we did not mention was the importance of reserve vacuum. You also need to factor in the vacuum that is needed to run a manual releaser (at least 5 CFM) and anything else like lifts and vacuum piston pumps. All of these eat up CFM. You do not want to be maxed out on CFM capacity when Mr. Bushy Tail shows up. Factor in another 3 – 5CFM in reserve vacuum and hope he does not bring his relatives. Your system need capacity to recover from leaks and other unforeseen problems and it need to do it as quick as possible. In my small world of maple production I am not comfortable with anything under 35CFM. Here’s why! Our home woods only have 400 taps, the requirement to run those taps is only 4 CFM but I have maxed out a 35 CFM pump. Here is how we did it. First we have long mainlines because the woods is spread out. Secondly most the lines drain to a low point that is totally inaccessible to sap pickup. We use a lift to bring the sap forward to the releaser. We then move the sap from the releaser tank to road via vacuum operated piston pump. No one in their right mind would have put tubing these woods but we did and it works. We maintain 25 inches at the releaser, 22 inches of vacuum at the lift and 18 to 20 inches at the end of the mainlines. I will replace that pump with a bigger one someday but in the meantime we are constantly looking for new innovative ways to conserver vacuum and utilize what we have in the best way possible. Just like everyone else we are spending countless hours looking for what Mr. Bushy Tail and his friends have done to our tubing. I cannot over emphasize the importance maintaining your system. The most important time you will invest in you maple syrup operation will be the time you spend in the woods managing your tubing system.
Footnote: Many producers are successfully rnning their vacuum systems over 25hg. They are successful because their system is properly designed and maintained.
The variety of vacuum pumps on todays market is very extensive. Although vacuum has become a mainstay in maple production our utilization of vacuum pumps and equipment is very small compared to their use in the industrialized world. Maple production is just on the tip of the iceberg when it comes to vacuum utilization. Even though vacuum is used extensively in the maple industry we have only been at it a very short time. For this reason there is a lot of misunderstanding about the laws of physics (Quantium Mechanics) that govern the science of vacuum. The online encyclopedia Wikipedia definesthe word vacuum as “void of matter”. In fact it stems from the latin word vacuus which means vacant. The study of vacuum goes back to the Greek Age and the time of Aristotle. Several basic scientific principals apply when it comes to vacuum. Due to pressure exerted by the earth’s atmosphere (15 lbs per sq. in.) you can only achieve a maximum vacuum level of 29.92 inches of mercury. You actually can only achieve a vacuum level equal to the barometric pressure on any given day at any given location. Barometric pressure changes with the elevation above sea level. Another principal is how we measure vacuum. The level of vacuum is a negative measure (because you are creating a negative pressure inside of a vessel) and is read in inches of Mercury. The rate of air being removed from a vessel by a vacuum pump is measured in cubic feet per minute on an English measurement scale.
Even though it has become the Holy Grail, in the maple industry, the term “High Vacuum” is largely misunderstood. High Vacuum or perfect vacuum exists only at 29.92 in. Hg. This is the highest level of vacuum achievable in our atmosphere and occurs only when every molecule of matter is removed from a vessel. This is extremely hard to achieve because once all of the air is removed there are still other gases that qualify as matter and are very hard to remove. In fact the closest thing to a perfect vacuum only exists in outer space and we are not producing syrup on the moon. Wikipedia states “There are three levels of vacuum achievable with modern vacuum pumps. Low vacuum (vacuum cleaners), Medium Vacuum (achieved with a single pump) and High Vacuum (achieved with multi-staged pumps and measured with an ion- gauge).” As you can see the vacuum we use falls in a range of somewhere between low and medium. Obviously the average maple producer does not live in the scientific world of vacuum, nor does he need to. The reality is that we are not dealing with a closed vessel but rather miles of tubing where the introduction of air occurs at every tap, fitting and squirrel chew. The range that most maple producers should be comfortable with is around 20 in. to 27 in. of vacuum depending on their system and the pump they are using. The reason being is that, this is that all vacuum pumps are not created equal and vary greatly in their ability to produce vacuum. Now this is where the discussion and the debate begin. As I have stated in an earlier post (March 25, 2013 Is it The Pump or The Mainline Size That is Effecting the Performance of Your Tubing System?) the producer must consider the entire system before he decides on the type and size of vacuum pump to use. Even though we are increasing the volumn of sap being produced by increasing the level vacuum closer to 29.92 we need to be more concerned about the ability of the whole system to remove air from the system efficently. Rather than concentrating on achieveing the maximum depth of vacuum we should be paying closer attention to the systems ability to overcome leakage and everyday wear and tear.
There is a wide variety of vacuum pumps that can be used to apply vacuum to a maple tubing system. In fact with the use of 3/16 tubing (based on the research of Tim Wilmot at the Proctor Maple Research Center) you may not even need a vacuum pump to achieve your vacuum goal. Most of the pumps used in the maple industry are adapted from some other type of use. The first pumps came from the dairy industry and were used to milk cows. These were rotary vane pumps that were designed to produce around 16 inches of vacuum. The vacuum was produced as the air trapped between the vanes held in an offset rotor was expelled to the outside via the exhaust. As the vacuum level increases heat is builds as a result the system needs some kind of lubrication to absorb the heat. The pump is lubricated with oil that was contained in an oil reservoir. Once you went above 16 inches the strain on the pump produced more heat that it was designed for. For that reason oil coolers and oil-reclaimers were used to make them more efficient. Bearings need to be lubricated with a precise amount of oil to maintain function. When running above 20 in hg, if any of the above are neglected you are headed for a Chernobyl type melt down. There are commercial rotary vane pumps (running a flood vacuum) on the market that are capable of achieving up to 27inches of vacuum. One of the most popular pumps being used is the liquid ring pump. The liquid ring pump uses an impeller running in a ring of liquid producing close to 29 inches of vacuum. As the air is drawn in it becomes trapped in a compression chamber that is formed between the impeller veins and the liquid. The air is expelled to the outside as the liquid (oil or water) is recycled. These pumps achieve as close to 29 inches of vacuum as any pump on the market. The down side of this type of pump is that a water source is needed and that source needs to be kept above freezing. If oil is used then there are environmental considerations.
One of the most recent pumps to come on the maple scene is the rotary claw pump. The rotary claw will produce 27 inches of vacuum, just under a liquid ring. This is a pump that is designed for continuous duty and one that requires minimal maintenance during the season. The claw runs at a very close tolerance to the chamber and traps air in-between the claws and the chamber and expels it to the outside. A small amount of oil is used lubrication. The downside is that these pumps are very expensive. They are designed to be run year round. Long layover periods may allow the pump to develop a rust layer inside to the pump resulting in excessive air. Because they run at a very close tolerance this may lead to early breakdowns. If you buy a rotary claw you need to fog the pump with anti-oxidation oil in the off season to prevent premature wear.
The last pump is the new age rotary vane pumps that are designed to run continuously and to produce a vacuum of 29 inches. This appears to be a very efficient pump. These pumps are similar in design to the older rotary vane pumps but have very close tolerances. They lubricate with oil but total requirement is minimal. So let’s rate the pumps on their ability to produce high vacuum from top to bottom. At the top is the liquid ring and the new age rotary vane with the edge going to the liquid ring especially one of the two stage models on the market at this time. These pumps will consistently reach 27 to 29 inches of vacuum. Not far behind is the rotary claw which will produce 27 to 28 inches of vacuum. Next is the improved rotary vane with a flood system at 27 inches. At the bottom is bossy’s favorite the old style rotary vain used in milking systems. She liked it because it produced no more than 16 inches of vacuum. Any more and she would send it across the room with one swift kick. No matter what you use you will get more sap from you trees. Collecting maple sap with a vacuum system not only saves time and labor but the vacuum will increase your sap yield by up to between 50 % and 150%. In the next post I will cover things you need to consider before you hook your pump into the system.
Ohio State University Extension Geauga County
(This is a follow-up post to the July 16th post on leasing and evaluating maple stands. It contains more questions than answers.)
Over the Thanksgiving holiday I had a chance to read in depth the latest edition of The Maple News. What caught my eye was and articles about a recent scientific study concerning with the health of the maple trees in the Adirondacks Mountains in upstate New York. The article documented the relatively slow growth of the sugar maple trees in that region. For many reading articles like these, the importance does not always hit home because it is about a potential problem in an area that is a long way from the home sugar bush. Therefore, why should we be concerned? The answer to that question became all too clear after attending a two day planning meeting on woodlot management held at the Holden Arboretum in Kirtland, Ohio.
The Holden Arboretum is considered to be one of the top Arboretum’s in the country. Their research on trees is highly respected around the world. The arboretum covers 4000 acres and includes all types of hard and soft wood species. It also includes the sites of several old sugar bushes and a grove of super sweet trees. One of Holden’s latest projects is entitled the “Working Woods”. It is setup to take a hard look at how local woodlots are managed, for not only timber sales but forest products including maple syrup production. The initial meeting was more of an introduction to the project and a chance to share opinions on the subject of forest management. The group sitting at the table included arborists from several states, commercial foresters and foresters from the Ohio Division of Forestry, along with members of the Holden staff. I was fortunate to be selected to represent the local maple syrup industry at this meeting. What I was able to take home from the discussion changed my prospective on forest management. I quickly became aware that there are many things we need to be concerned about regarding the health of our trees and their future.
For several years now, one of my projects at the Geauga County OSU Extension has been to examine what is happening to the maple tree resource in NE Ohio. This project entitled, “Preserving Sugar Maple for the Next Generation”, is finding out that NE Ohio maple syrup production may be entering a new phase. After WWII just about every farm (most were small dairy farms) in NE had a sugar bush. The sugar bushes were small and there were many individual sugar camps in a square mile area. This gave the appearance of an endless supply of maples to tap. Fast track to the year 2000, most of the small dairy farms are sold because their owners could not keep pace with the modern expansion of the industry. Many of the sugar bushes are cut down and replaced with housing developments. This type of development also increases the demand for home furnishings. One of the most popular furniture’s today is made of hardwood which includes maple. It is no surprise that Ohio has become one of the leading producers of hardwood furniture in the country. That industry is centered in Holmes County just 60 miles from the Geauga County. Suddenly there is a new interest in the maple tree and it is not only for syrup production. Tracts containing old sugar bushes are being harvested at a steady pace to keep up with the demand of the furniture industry. This would be ok if we lived in an area where there were expansive tracts of timber but we do not. Instead we live in an area where there are small woodlots, 10 to 20 acres that cannot stand extensive harvest. To make matters worse the people doing the logging feel that the only economical cut they can make is a clear cut. Selective cutting just does not generate enough revenue to bring in a mill. As a result NE Ohio has become the poster boy for bad logging practices.
One of the things I learned at the Holden meeting was that along with increased harvest our maple trees are now coming under increased environmental pressure on multiple fronts. We live in world of invasive species, natural imbalances and yes the dreaded term, climate change. As the article on the Adirondack forest maples pointed out, trees that should be thriving are just not growing at the rate they should, do to multiple factors affecting their growth. In Ohio we have also seen increased pressure from wildlife and insect damage on the surface and earthworm damage from beneath the soil. Both have led to reduction in the regeneration of young trees to replace the aging trees that will soon be lost. I was able to document this at Holden over the last 8 years. While recently standing in the middle of the Holden Arboretum Working Woods demonstration sites (an Old Sugar bush) I was very alarmed at the lack of regeneration that had taken place over that span of time. The question came to mind; if you are unable to regenerate a new growth in a well-managed woodlot, within an arboretum, what are the chances of maple trees coming back in a site that had been clear cut for timber production? The answer to that was all too obvious. Only under the best circumstances could a clear cut woodlot come back into maple production. Unfortunately in NE Ohio, Best Management Practices in logging are seldom used. This leaves one to ponder; with 60 % of Ohio’s maple syrup currently being produced in NE Ohio, what will the Ohio Maple syrup Industry look like in 2050? The bigger question is what will be needed to protect this valuable resource.
One of the facts produced by the OSU study is that the risk to maple trees is significantly higher on private property, than on public property. There are still good healthy stands of maple trees growing in our parks and on other publically owned land. However, even those maple stands are under constant pressure from expanding poorly managed deer herds. For the most part we will always have stands of maple on public lands; it is the maples in privately owned woodlots that are at risk. The goal of both of these projects is to educate private landowners on how to manage woodlots on their property. The education process starts by showing a landowner what the options are for available for woodlot utilization and management. Beyond that, they still need to be convinced that the best way to make those decisions to seek professional help before they sign any contractual agreement. This means that certified foresters need to be brought in appraise the resource. If they decide not to cut and to go with maple syrup or sap production then they need to contact someone who can show them how to make that happen. As Cornell University Maple Specialist Dr. Michael Farrell points out in his book, “ A Sugarmaker’s Companion”. “Often the best way to save a maple tree is to utilize it for maple syrup production”.
It is not the intention of anyone to dictate what a landowner should do with his or her property. Certainly if they have made up their mind to harvest the timber for whatever they are offered, they have the right to do that. The big problem here is that what looks good on the surface does not always end up that way and there are often regrets when the process is completed. We need to make sure when a woodlot owner makes a decision it is an educated decision. Hopefully somewhere along the way we will see less woodlots with maple trees being cut down and more going into maple syrup production. In the mean time enjoy the hours you spend in your sugarbush and never take the sweet gift of making maple syrup from these magnificent trees for granted.