M. M. Hunting
An apparatus for producing a blast for a small blow pipe by water power may be made in the following manner.
A piece of 4-in. iron pipe, 6 ft. long, is fitted with a cap at each end. About 1 in. below the cap at the upper end, drill and tap a hole and screw in a short piece of 3/8-in. pipe; C, Fig 1. At the other end, about the same distance from the cap, drill and tap a hole for a 1/2 in. pipe and screw in a short nipple to which may be attached the exhaust pipe 2 1/2 in. long, with valve as shown at B, Fig 1.
In the center of the cap at the upper end of the large pipe a hole is drilled and tapped for a 1/2-in. pipe and the aspirator shown in Fig. 2 is attached at this point
The aspirator is made asfollows: In a piece of 1/2 in pipe 4 in. long and threaded on both ends, drill four 1/4-in. holes, B, Fig. 2, at equal distances around the circumference, and at a line on the pipe equi-distant from the ends.
Into one end of this piece run a 1/2-in. tap so as to thread the inside of this pipe down to the point where the hoies are drilled. Cut a thread 2 in. long on a piece of 3-in. pipe and screw it into the 1/4 in. piece until the end comes nearly down to the 1/4-in. holes; A, Fig. 2. Saw off the other end flush with the end of the larger pipe.
An elbow may now be screwed on the upper end of the aspirator for convenience in attaching to the source of water supply. The lower end should be screwed tightly into the cap on the large pipe.
When a stream of water enters the aspirator at A Fig. 1, it draws in the air through the four smalt holes. As the water rises in the large pipe the air is given a pressure and flows out of the small pipe C, Fig. 1. A rubber tube connects this pipe with the blow pipe.
The valve B may be connected with a waste pipe and should be partly closed so that the water may rise in the large pipe enough to give the air an even pres-sure. All threads should be well leaded before screwing together in order to secure air and water-tight joints.