JACK PINE AND HEMLOCK FOR MECHANICAL PULP. 9 



Swing cut-off saw American Pulp and Paper Association. 



3-ton scale Paper (Inc.). 



2 Ash ton relief valves Do. 



1 pulp truck W. A. Lounsberry & Co. 



1 wood truck Do. 



1 54 by 27 inch pulp stone Manufacturers' Paper Co. 



12 42-inch screen plates Union Screen Plate Co. 



1 wet-machine felt Albany Felt Co. 



1 wet-machine felt Appleton Woolen Mills. 



1 set barker knives Dowd Knife Works. 



1 set sectional and solid burrs. .Ticonderoga Machine Works. 



Plate I shows a portion of the pulp-making equipment. The 

 grinder (PL I, fig. 2) has three pockets, the cylinders are 14 inches 

 in diameter, and it is designed for a 54 by 27 inch pulp stone. Each 

 of the grinder cylinders is equipped with a pressure gauge, and the 

 pressure line between the triplex pumps and the grinder is provided 

 with Ashton relief valves, which make it possible to obtain very 

 uniform pressures up to 100 pounds per square inch. 



A recording thermometer gives a record of the temperature in the 

 grinder pit. From the grinder pit the pulp is passed through a 

 mechanically agitated sliver screen, then pumped to a storage tank 

 by means of a 6-inch centrifugal pump, and from there pumped to a 

 centrifugal screen. A variable-speed motor direct connected to the 

 screen makes it possible to obtain speeds of rotation from 400 to 600 

 revolutions per minute. Throughout the tests, however, the speed 

 was maintained at 500 revolutions per minute. The plate in the 

 centrifugal screen is perforated with holes 0.065 inch in diameter. 

 The tailings from it are led by gravity to a 12-plate horizontal dia- 

 phragm screen, the plates of which are the Union Screen Plate Go's, 

 type B, cut with 0.012-inch slots. 



The good pulps from the centrifugal and the plate screens are 

 united in the vat of the wet machine, which is direct connected to a 

 variable-speed motor giving felt speeds ranging from 75 to 115 feet 

 per minute. The wet machine is provided with a small triplex pump 

 by which the cylinders connected to the press rolls are operated, the 

 dryness of the pulp being determined by the pressure applied to the 

 cylinders. A vacuum of from 10 to 15 inches, produced by a rotary 

 suction pump, is maintained on the felt, and this, too, assists in 

 obtaining the desired dryness of the pulp. The white water from 

 the wet-machine vat is pumped back to the grinder sliver screen by a 

 4-inch centrifugal pump. White water from the felts is run directly 

 to the sewer, as is also the white water from the felt suction. Plate 

 I, figure 2, gives an idea of the general arrangement of the pulp- 

 making machinery. A 40-inch swing cut-off saw and a Green Bay 

 wood barker are used to prepare the wood. 



