Today I want to talk about spray bars in your highbanker, there are so many variations that work well and then there are many that don't in all conditions I'll try to cover off all the variations I've tested in this article.
PVC Highbanker Spray bars
My first spray bar was a simple PVC wraparound type that while it looked nice it didn't achieve what i wanted it to. Not only was it clunky as in needed to be cable tied in four to five places but I found that the pressure simply wasn't enough to clean the rocks properly. I tried many small holes in each and every direction then i tried a few large holes with small ones in between, my conclusion was that i needed more water coming out quicker and without weed getting stuck.
Poly pipe Highbanker Spray bars
By far my favourite to date and the most effective in most cases, poly pipe has served me well and I still use it today. By far the easiest to work with, cheapest to buy and the only downside is the cost of fittings like elbows etc. So you need to weight things up these will work the best if you are in a clay like area or have very dirty cloggy pay-dirt. I take two variations out with me in the field one for all purpose that has heaps of pressure and its all i need 99% of the time.
As you can see I use the blue lines on the pipe to mark how deep i cut and have found that any further than 3/7 of the pipe you will cause the pipe to blow-out under pressure. Pressure is key because we want to wash those rocks real good and we want to see if a nugget falls off the back during the classifying process. I generally cut these 3mm wide and around an inch apart, it will depend on your pump and the pressure you run as to how many slits you want. This 3mm gap works best when your likely to pick-up grass or weed in your pump, anything smaller and you'll get clog ups. I've intentionally taken a photo with the weed to show you what happens, this spray bar was still working perfectly fine with the grass lodged.
The above example is a very fine slit and this pipe bends considerably under pressure, its designed to laser cut clay. I use this spray bar only when throwing clay through the highbanker that I know is gold rich. This in conjunction with a a piece of mesh in the hopper that holds the clay works really well for clay ripping.
I'll post up another article about the methods i use for clay another day.
If you are like me and would rather things came cut and ready to put together then you'll love this set-up, i found these i the toilet plumbing section at Bunnings recently and the lengths are just perfect, the whole thing cost around $15, I don't know what type of plastic it is but its hard as rock and about 4mm thick. I love this one in particular because the pipe comes pre threaded so I can make as many variations of spray bar as i like and twist them on and off to suit without using any hose clamps or fittings. Whilst two spray bars is not detrimental these are situations where you want to blast the material in your highbanker hopper and then you want to blast it through the classifier as well, many times rocks will stick to clay as they tumble and we want that clay blasted off and into our highbanker and sluice.