544 



CHAPTER XXVII 



discharged. This discharge is controlled by the conical valve, H, which 

 also has a rubber seating, and thus a joint is formed against the wall of the 

 tank at S. 



It will be seen that the liquid is delivered on to the tun-dish, Q, connected 

 with the outlet valve, H, and the weight of the liquid on this tun-dish has the 

 effect of holding the valve open until all the liquid is drained from the 

 weighing tank. This valve returns by means of the weighted lever, M, when 

 relieved of the weight of the liquid on the tun-dish, Q. 



The sides of the tank are continued down to prevent splashing, and a 

 mechanical counter, R, registers every weighing. 



Another juice weigher, the Leinert Meter {Fig. 348) consists of two tanks 

 of equal capacitv A-^ and A 2', they are balanced on a knife-edge B; at C is a 

 syphon pipe and at D is arranged an adjustable counter- weight. The juice 

 discharges from the pipe E into the gutter F, which is tilted one way or the 

 other by the movements of the tanks. The juice flows into one tank until 

 the weight is just sufficient to counterpoise that at D, when the tank tilts 



Fig. 348 



into the position shown by the dotted lines and allows the juice to discharge 

 through the syphon ; simultaneously the gutter is tilted and directs the flow 

 of juice to the other tank. The number of fillings is registered by an auto- 

 matic counter. 



In the absence of these devices resource must be had to measurement 

 in tanks. These should be provided with an overflow, and the juice should 

 be allowed to enter until it discharges over a wide weir, the excess being 

 allowed to return to the pump suction. To reduce the error in measure- 

 ment, tanks are sometimes built with a constricted upper portion. 



It is not a hard matter to accurately gauge a tank or to fill it to a constant 

 level, but the accurate volume measurement of juice requires attention as 

 regards the following points : — i. Allowance must be made for the juice 

 retained by capillary attraction at each emptying. 2. The volume of air 

 entrained must be ascertained. This is best done by filling the tank to the 

 overflow, and allowing to settle for some time and noting the decrease in 

 volume. 3. The suspended solid matter must be ascertained and allowed 

 for. 



The corrections for these three sources of error can only be average 



