Flex tubing on all PERC’s.
Some of the most valuable information I get comes from the field. Probably the most perplexing has been units several months old that seemed to decrease in their toxicity to kill gophers. The answer had to be air contamination of the exhaust gasses, but everything was tight with no visible air leak. When the unit was new, it worked great. After several months, there seemed to be more and more gopher mounds showing up in the area treated.
I figured it out, but it took some serous head scratching!!
The contamination problem was (and is) coming from the SS flex tubing from the motor to the cooling coils and from the cooling coils to the compressor. Vibration has always been a serous consideration and it reared its ugly head once more.
The flex tubing is really a long strip of light weight stainless steel that is formed to hook together in a spiral. Tolerances are tight and when new, it is close to air tight. But with use, the units vibration causes continue flexing of the tubing and causes the joints to create very small cracks that will leak.
There is positive pressure inside the tube from the motors exhaust and it has been assumed that this positive pressure would overcome any cracks that developed from use. But we missed one very important fact. The positive pressure works great when it is blowing towards the hooked joint. When it is blowing away from the hooked joint, it causes a vortex in the V formed by the joints which in turn creates a venturi effect. This vortex will actually cause a vacuum that will draw outside air into the exhaust stream in the flex tube. This creates a venturi effect and introduces air contamination to the exhaust reducing its ability to kill rodents.
On the 620 and the 412, this is very easy to fix. If the unit is within a year old, the flex tube can be inspected and if the folded portion of the joints point away from the motor or exhaust flow, it will not suck air. If it is pointed towards the motor, it will suck air.
If the fold is pointed towards the motor, take the clamps loose and reverse the direction of the flex tube and re-clamp it. If the unit is over a year old with heavy use, the tubes should be replaced. Either we can furnish the tubes or they can be bought from most auto supply stores.
The flex tubes on the 206 pose a bit of a complication. I have not found exhaust pipe clamps that will fit on the one inch tubing we use. While we can furnish the rings, the tool needed to tighten them up is the band-it junior and is a special tool. Heavy duty screw type clamps can be used in combination with a high temperature gasket sealant. Any exhaust gas that leaks will be minor and in this situation, air will not be sucked into the exhaust stream contaminating it.
I am drawing up an illustration that will have both graphic form and written instruction that we will mail to PERC owners. I appreciate your patience and want you to know that we are dedicated to keeping all our units in the field working.
Allen
Uncategorized | admin January 28, 2010
