Spray Bars: Holes v's Slotted Comparison

[elbowgrease]

Hi Folks

Had the pleasure of catching up with golddoctor last weekend, taking up his offer to come and have a dig around one of his local haunts.

Being the first proper field test of my highbanker it was a good opportunity to get a look at how it ran, among other observations I wasn't completely happy with a few dead spots in the hopper where water coverage wasn't great.

The existing setup is three rows of 3mm holes, the upper most row holes spaced 2cm apart, the middle and lower rows holes spaced 4cm apart and offset 2cm from each other. While in the field I noticed, despite cranking the pump up to flat out, I couldn't seem to get much more volume through the box so I ended up drilling out the middle row of holes on both sides out to a 4mm hole which made a noticeable difference.

Alas even with an improvement in water volume it didn't really help the dead spots in the hopper so I've redesigned a set of spray bars with angled slots.

I've taken a quick video of both sets of bars running side by side installed in the hopper. At first glance the slotted spray bar looks better, it will undoubtedly still need a bit of tweaking but it looks like a good starting place. Video quality isn't great, just taken on my phone and blowing a gale outside.

I'd love to get peoples feedback on their experiences with slotted or drilled bars and what you might have found to be pro's and con's for each.

Cheers
Adam

[video=480,360]http://youtu.be/TMXDzVhTTc4[/video]

 

[rc62burke]

Hi Adam
Mate I had a look at the vid, to me it looks like not enough flow or volume for either side, holes or slots.
I think the holes would be better, but start them at 2mm dia & keep them closer together ( this means keep the rows closer together less degrees of separation) try rows 5mm apart.
In the Vid was the pump flat out? what size pipe do you run from pump to hopper you may have friction loss? show us your pump set up.
Lee

 

[WalnLiz]

G'day Adam.

Firstly what's the Litres/min rating on your pump, as this will dictate the kind of washing procedure you will have to take. The holes will need fairly high water pressures to deliver any sort of water volume....and volume is what you're after. The spray bar is a better option, but again reasonable delivery is required.

You don't need spray over the full length of the grizzly, so if you were to run with the spray bar version I would cut them back to 3 either side instead of 6 and make the slots wider using a drop saw blade if possible.

Another option if the pump has low volume is no spray at all and rely on directing the full volume of water without pressure onto the grizzly. This would require a slight change of the plumbing and take me a full page to describe it. Send me a PM and i can go through what i call a flood method of washing and I'll explain the technique with some pictures.

Cheers Wal.

 

[elbowgrease]

The pump in the video isn't going great guns maybe 1/4 - 1/3 throttle.

Its a Aussie Pumps GP1/GX25 Honda 4 Stroke 1hp 1" Pump. Max Flow 120 litres per minute.

I went with that pump for a couple of reasons, firstly its light. 5.4kg dry weight, the next part is 1" pump means 1" layflat and suction hoses which again saves a lot of weight. The highbanker is 250mm tapering down to 210mm and the couple of field tests I've run the volume of water is pretty close to right without revving the guts out of the pump.

rc62burke When I'm running that pump in the backyard (as in the video) I'm just using 1" suction hose from the outlet on the pump up to the spray bars which are 1" PVC pipe.

Wal I'm familiar with the flood method of washing. I think to go that way would take some redesigning of the hopper as I'd need to shoot the water in from the (currently) open end similar to way the dredge inlets on the US style highbankers often have. I suppose I could use the existing holes and fashion some backwards pointing PVC pipe to dump the water in instead.

The last slot on the slotted spray bar I made fires a bit to close to the end. If I had my time again I'd probably have not put that one on, I might even look at filling it with glue or something. Unfortunately I don't have a drop saw so I did that this morning using a hacksaw.

 

[rc62burke]

Hey Adam
The best thing is mate, the pvc is cheap & easy to work with to adjust your sluice, try 2 rows of holes, you want the sprays from 1 bar hitting an area of 100mm in the hopper Don't glue the spray bar as it gives you some adjustment in the field until you get it sorted. from your description of the pump ( I don't know it) you need small holes closer together like I said before.
cheers
Lee

 

[elbowgrease]

Hey Adam
The best thing is mate, the pvc is cheap & easy to work with to adjust your sluice, try 2 rows of holes, you want the sprays from 1 bar hitting an area of 100mm in the hopper Don't glue the spray bar as it gives you some adjustment in the field until you get it sorted. from your description of the pump ( I don't know it) you need small holes closer together like I said before.
cheers
Lee

G'day Lee

The Aussie Pumps GP1/GX25 is bassically identical to the Honda WX10. Both the Aussie Pumps and the Honda use the same Honda 1hp motor, the only difference is in brand of pump head. The stats (max flow, max head, lift) are pretty well identical but the Aussie Pumps version is about $180 -$200 cheaper.

I think you might be right, its just going to take some fiddling around and testing a number of setups before I get it right. Luckily I had the foresight to know it was going to take a few goes at, so the back half of the spray bars is all glued and sealed but the bars themselves are removeable! (yay for planning!!!)

Last night I re-made a set of slotted bars, both sides with 5 slots each side. (got rid of the one from the video as the 6th slot sprayed right on the end of the grizzly)

I've still got another 2 "lengths" of PVC, enough to knock up another two sets of spray bars.

I find its kind of difficult to compare water volume visually when swapping out the different bars, like there is obviously a point where there is clearly not enough, but after that it all kinda looks "about right". I know the pump can supply enough water to make it work as the field tests have proven that, whether its enough water to scrape by or if considerably more would be more ideal I really don't know.

Cheers
Adam

 

[rc62burke]

Hey Adam
Something else you may like to consider is, screw caps on the end of your spray bar to replace the glue on ones, so you can remove them for cleaning etc.
cheers
Lee