MAPLE SIRUP PRODUCERS MANUAL 



51 



PN-4771 



Figure 81.— A steam-heated finishing pan, Uke a gas-fired pan, provides positive control of the finished sirup and 



eliminates danger of scorching. 



When a finishing pan is used, the following 

 procedures should be observed: 



(1) Do not finish more than 5 to 10 gallons of 

 sirup in a batch. 



(2) When the sirup is finished, that is, when it 

 reaches the proper temperature (7° F. above 

 the exact boiling point of water), heating must 

 be stopped immediately. 



(3) Drain all the finished sirup from the pan. 

 If any sirup is left in the pan, it will darken the 

 next batch. 



(4) Use two finishing pans alternately. 



Aiitoinatic Drawoff 



An automatic drawoff is well suited for draw- 

 ing the partly evaporated sap from the evapo- 



rator for later completion in the finishing pan 

 (fig. 82). A high precision thermoregulator is not 

 required, since a tolerance of ±0.5° F. is accept- 

 able. Corrections need not be made for slight 

 changes in the boiling point caused by changes 

 in barometric pressures throughout the day. 



Automatic valves can be purchased as com- 

 plete packages, or they can be assembled as 

 indicated in chart 10. These valves are operated 

 by a solenoid, which in turn is opei-ated by a 

 thermoregulator. The thermoregulator is ad- 

 justed by hand to open or close the valve when 

 the boiling sirup reaches the desired tempera- 

 ture, as measured by a precision thermometer. 



A thermoregulator, if used to control the 

 removal of finished sirup from the evaporator 



