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AGRICULTURE HANDBOOK 134, U.S. DEPT. OF AGRICULTURE 



masonry or cast iron. The masonry arch or the 

 base of the cast iron arch should extend below 

 the frostline and sufficiently high above the 

 floor level so that the height of the evaporator 

 permits the sap to flow by gi-avity from the 

 pans to the filter tank and then from the filter 

 tank to the finishing pan. Setting the evapora- 

 tor high also makes it easier ^o fire when the 

 fuel is wood, and brings the thermometer (for 

 checking the boiling point of the sirup) to eye 

 level for ease of reading. 



If the sirup is only partly finished in the 

 evaporator and evaporation is completed in a 

 finishing pan, the finishing pan should be 

 mounted adjacent to the evaporator. 



Air Supply 



When the evaporator is in operation, great 

 quantities of outside air are required for com- 

 bustion of the fuel. For example, 150 cubic feet 

 of air per minute is required to burn seasoned 

 hard maple at the rate of one-fourth cord per 

 hour. If the steam is removed through an open 

 hood, an additional 10 cubic feet of air per 

 minute per square foot of evaporator will be 

 required. For example, an evaporator 4 feet 

 wide and 12 feet long requires 480 cubic feet of 

 air per minute to remove the steam through a 

 ventilator. 



If this air is supplied through an open door or 

 window, the evaporator house will be very cold 

 and drafty. A more desirable method is to 

 deliver air where it is needed. Ducts along both 

 sides of the evaporator will supply the hood 

 ventilation and the combustion air. These ducts 

 should be 8 inches wide and open at the top and 

 at the ends toward the firebox. They should run 

 the entire length of the evaporator. The air 

 coming in through these ducts tends to keep 

 the steam under the hood. If the evaporator is 

 covered and has a steam vent pipe, the ducts 

 will need to supply air only for combustion. 



Siriip-Proressinjj Room 



If the evaporator house is a single room, it 

 must have space for filtering the sirup and for 

 canning it. It is better to process the sirup in a 

 second room built as an "L" to the evaporator 

 room (chart 4). This arrangement does not add 

 appreciably to the cost of construction and the 



sirup can be processed under better working 

 and sanitai-y conditions. 



The processing room houses such operations 

 as filtering, heating, and packaging the sirup, 

 and making maple confections. The equipment 

 consists of a filter rack, a stove for boiling the 

 sirup (preferably heated with gas), a maple- 

 cream beater, and sugar stirrers. 



There should be a sink for dish washing, a 

 hot water heater, and a trough with cold run- 

 ning water in which sirup that has been cooked 

 for making maple cream can be cooled rapidly. 

 Storage space should be provided for cooking 

 utensils and containers. 



If the evaporator house is to serve as a 

 salesroom, space should be provided for display- 

 ing the products attractively and for storing 

 the products. 



Fuel Storagje 



When wood is used for fuel, sheltered storage 

 must be provided in a convenient location. This 

 storage space holds enough wood for a run of 

 sap. The supply is replenished from a larger 

 storage shed. In some large operations, the 

 wood is stored in a separate building and is 

 transported to the evaporator house in a truck 

 mounted on rails (fig. 76). An overhead tram- 

 way can also be used. By installing the tracks 

 with a slight downgrade toward the evaporator, 

 the heavy loads of wood can be moved by 

 gravity. 



Figure 76. — Wood for fuel is conveniently 



separate shed. The wood is moved in a flanged-wheel 

 truck that runs on rails to a point adjacent to the 

 evaporator. If the storage shed is at a slightly higher 

 elevation.'the loaded truck can be moved by gravity. 



