How To Build The Pump
-Most of the parts for this pump can be purchased at a hardware store. Here is a schematic of the shaft/plunger assembly:
The 1/2" PVC caps (non threaded) and the 1/2" sections of PVC pipe (non threaded), must be cemented into the 1/2" threaded Female PVC Tee. Only the bottom hole of the female PVC tee is threaded; that end threads into the 1/2" PVC riser AFTER THE 2" PVC CAP (DRILL A 7/8" HOLE DRILLED IN THE CENTER AND 3/16" VENT HOLES) IS PUT ON (AS SHOWN IN THE NEXT PICTURE). This cap will act help guide the pump shaft.
-To make the plunger, it is necessary to combine the small halves of two 2" wing-nut plugs. It takes two wing-nut plugs to make one plunger.
<--Two wing-nut plugs (before) <--After
-The shaft/plunger assembly looks like this assembled. The bottom two nylon lock nuts will be tightened later when you adjust the plunger diameter.
-Now it is time to make the pump housing. To do this cut a length of 2" PVC pipe about 1.5" longer than the shaft plunger length (see the picture below).
-Cement the 2" PVC cap (without the hole) to the bottom of the pump housing. DO NOT CEMENT THE TOP 2" PVC CAP TO THE PUMP HOUSING AT ANY POINT (YOU MUST BE ABLE TO REMOVE THIS TO SERVICE THE PUMP).
-You will need to get a bicycle pump hose with a pressure gauge. I bought a pump at K-mart for about $12, then I removed the hose/gauge assembly. This particular hose/gauge assembly has a built in check valve (only allows gas to flow out of the hose which prevents backflow of pressure).
-Next you need to assemble the rest of the pump parts, the following is the schematic for this:
-The 3/8-1/4" barbed fitting and the 1/8" MPT Hex nipple screw directly into the base of the pump.
-For the 3/8-1/4" barbed fitting, drill a 1/2" hole approximately 1-1/4" from the bottom of the pump (the threads are self tapping; they will screw right into the hole).
-For the 1/8" MPT hex nipple, drill a 3/8" hole approximately 1-1/4" from the bottom of the pump on the opposite side of the 3/8-1/4" barbed fitting (the threads are self tapping; they will screw right into the hole).
-To make a good seal, put a light application of clear silicone in and around the holes, and make sure to wrap the threads with Teflon tape (approximately 4-5 wraps). WRAP ALL OF THE THREADS WITH TEFLON TAPE (even the connection between the gauge and the 1/8" FPT coupler.
-After the fittings are screwed into the base of the pump, apply a liberal coat of silicone around the fixture, smooth it out, and let dry over night.
-Once the silicone has dried, it is time to install the inlet check-valve and hose (you can buy these liquid/gas check valves from http://www.usplastic.com). To do this, simply push the hose onto the barbed fitting attached to the pump then hose clamp it. Then insert the 3/8" barbed liquid/gas check valve into the other end of the hose (make sure the valve is arranged so the gas can flow in and not out of the pump), then hose clamp that.
-Now it is time to insert and adjust the plunger assembly. Start by applying a liberal amount of petroleum jelly around the outside edge of the plunger (just the part that will come in contact with the inside of the pump housing). This will lubricate the pump, and may need to be applied a few times as the pump gets broken in, and in the future to service the pump. Once the plunger is lubed, insert it into the pump housing, notice how the bottom two nuts are not tightened against each other yet.
-Tighten the bottom nut to increase the diameter of the plunger, and loosen it to decrease the diameter of the plunger. The plunger should have a snug fit, but not too tight so that it makes pumping hard. The plunger should be able to slide up and down with minimal resistance; however, it should be tight enough to make a good seal. Once these adjustments have been made, tighten the bottom two nuts against each other (make sure not to misadjust the plunger diameter while doing this).
-While the pump is not in use, the plunger will seize against the inner wall of the pump housing, THIS IS NORMAL. The plunger will feel "stuck" and is difficult to move at first. DO NOT TWIST THE HANDLE TO FREE IT, instead push down on the handle (as if you were pumping) to break it free. This is why you must leave the pump handle slightly up when you are done using it.
-The pump is now complete, it is time to capture Co2, this will be discussed on the next page: