MAPLE SIRUP PRODUCERS MANUAL 



43 



Fuel oil storage tanks must be large enough 

 to hold enough oil for at least 1 day's operation. 

 Larger tanks may lower delivery costs. The 

 tanks must be installed to meet local building 

 codes. 



Suinniaiy 



(1) If possible, locate the evaporator house on 

 the main road close to the other farm 

 buildings. 



(2) Build it large enough to provide at least 4 

 feet of free space on all sides of the evapo- 

 rator. 



(3) Construct it so that it can be kept clean. 



(4) Provide a w^orkbench along one w^all. 



(5) Provide the evaporator with a cover and 

 steam vent pipe. 



(6) Elevate the evaporator arch on a founda- 

 tion that extends into the ground below 

 the frostline. 



(7) Make the floor of concrete or other easily 

 cleaned surface. 



(8) Provide ducts in the house for intake of 

 outside air. 



(9) Set the evaporator high enough above 

 ground to raise the pans a minimum of 4 

 feet above the floor. 



(10) If possible, provide a separate but adjoin- 

 ing room for processing the sirup and mak- 

 ing other maple products. 



(11) If possible, equip the house with running 

 water, electricity, and gas fuel supply. 



(12) Provide adequate storage for dry wood or 

 oil. 



(13) If wood is used for fuel, provide means for 

 transporting the wood to the evaporator. 



(14) Locate the sap storage tanks outside the 

 building. 



(15) Cover the tank with material (plastic) 

 transparent to the low ultraviolet radia- 

 tion of daylight. 



(16) If the tank is enclosed, illuminate the sap 

 with germicidal lamps. 



THE EVAPORATOR AND ITS FUNCTION 



The maple sirup evaporator is an open pan 

 for boiling water from the sap. Although the 

 primary purpose of the evaporator is to remove 

 water, it must do the job economically and in 

 such a way as to improve but never to impair 

 the quality of the sirup being made. 



Maple sirup evaporators have gone through 

 an evolution in design. The first evaporator, 

 used by the Indians, was a hollowed log in 

 which water was evaporated from the sap by 

 adding hot stones. The next evaporators were 

 metal kettles used by the white settlers. Both of 

 these were batch-type evaporators, that is, the 

 entire evaporation process, from the first addi- 

 tion of sap to the last, was done in one kettle. 

 Sap both high and low in sugar content was 

 added. It might be many hours before the sirup 

 was finally drawn. As a result, a dark strong- 

 flavored sirup was produced. 



The next improvement in evaporators was 

 the use of multiple kettles (fig. 77). This evapo- 

 rator was the forerunner of today's continuous 

 evaporators. 



The sap was partly evaporated in the first 

 kettle, transferred to the second kettle for fur- 

 ther concentration, and then finally transferred 



to a third and sometimes a fourth kettle where 

 evaporation was completed. The multiple-kettle 

 method was a semicontinuous operation and 

 resulted in an improved (lighter colored) sirup 

 because the time of heating at near-sirup den- 

 sity was shortened. 



The source of heat for all the early evapora- 

 tors was an open fire, which is poor in fuel 

 economy. 



The first major change in design of evapora- 

 tors was the introduction of the flat-bottom pan 

 and the enclosed firebox (fig. 78). Both the 

 increased heating surface of the pan and the 

 confined fire increased the efficiency of the fuel. 

 This design was quickly followed by partitioned 

 pans, which were the forerunner of flue-type 

 evaporators. 



The modern flue-type evaporator, developed 

 about 1900, was the next and last major change 

 in design. Use of "flues" or deep channels in the 

 pans, and altering the firebox so that it arched 

 the hot gases between the flues, caused the hot 

 gases and luminous flames to pass between the 

 flues before escaping up the chimney. Fuel 

 economy was increased. Also, the rate of evapo- 

 ration was increased, which shortened the 



