Vacuum Static Gap
I use a single vacuum static gap. I use an 8 inch PVC drain that connects to 4 inch PVC. The vacuum motor
is a 1.5HP motor from a $30 Sears Craftsman Wet-Dry Vac (Sears item #00917713000, Mfr. model #17713).
The intakes are made from 3/4 inch PVC, four 3 inch pieces and two 6 inch pieces. The ends are made from
threaded PVC fittings with 3/4 inch to 1/2 inch brass reducing couplers. The openings on the brass couplers are
3/8 inch. I do not glue any of the parts together, except where they connect at the t-joint. This allows me to
easily make adjustments to the gap size and to ensure the electrodes are lined up properly.
To make the cover, I simply trace the removable drain cover on a 1/4 inch piece of plywood. I also do the
same on a sheet of paper, cut out the circle and fold it in fours to create a template to mark the center of the
plywood. After cutting the plywood disk, I drill a small hole in the center, put a bolt through it and throw it in a drill. Spinning the disk against a file or rough sand paper gives a near perfect circle. I then
drill the hole for the t-joint.
On the lower 8 inch side of the drain, I drill two 1/2 inch holes to serve as the exhaust for the vacuum motor.
I extend the bottom of the drain with a section of 4 inch PVC. This is to accommodate the cooling fan that
comes on the motor. The bottom edge has six 1/2 inch holes to provide intake for the cooling fan.