"lab test"

[Mountain View 14]

Ok folks, this is my first “lab test” using two panels of a fence between my neighbors house and mine. I would welcome comments about what I did right and/or wrong. Remember, I’m still new to this, try not to flame me too bad.

Specifics:

Fence is about 6 year old cedar (I think), never treated, faces east with not very much direct sunlight. Grayed with some mold and algae.

Left side was treated with percarb mixed 6oz/gal and allowed to soak for 15minutes. It was kept wet with product to stop it from drying out.

Right side was treated with 1.5% sodium hypochlorite (6% cut 1:3 w/water). It was allowed to soak for 15 minutes and kept wet with product to stop it from drying out. I haven’t been able to source 12.5% liquid product yet, hope my math is right.

Both sides were rinsed with a 3700psi/4gpm cold-water unit with a 25 degree #12 tip for five minutes. I held the tip no closer than six inches from the wood, usually 8-10 inches.

Oxalic was applied to both sides (3 oz/gallon), kept wet, let dwell for 10 minutes and rinsed the same way as above.

To say this stuff furred up is putting it mildly. Did I do something wrong? Did this happen because it’s old, untreated, and probably low-grade wood? Is sanding/defurring just something that needs to be done in this case? I’m trying to do this right, so if I’m going down the wrong road, I’d like to be corrected and adjust the way I do things sooner rather than later. Thanks for the help.

[Mike Stahmer 14]

I dont notice any change of GPM with my unloader set low I dont think!! WHat is the point of having it if it doesn't serve the purpose! I dont understand how adjusting your unloader can damage a pump! I have been usning my same pump for six years with no problems and I have changed the pump oil 1 time! Go figure! I am not a power washer mechanic or expert but I would really like to know if GPM's change with the unloader adj and what is accually the best way to accomplish low pressure/high volume

[PressurePros 249]

I know this has been debated before, but I disagree. Your pump puts out a certain amount of water, say 5gpm. That water has to go somewhere, whether it is flowing out of the trigger gun or going back to the tank via bypass. If you're using a #10 nozzle to get 1000 psi, then all the water is flowing out of the trigger gun. If you then back the unloader down to where you're only getting 500psi from the trigger gun with a #10 tip, then you only have approx. 3.5gpm coming out of the trigger gun. The other 1.5gpm has to be going somewhere, and it can't be out of the trigger gun, our you'd still have 1000psi. It HAS to be bypassing.

No Mike, you don't back off your unloader to 500 psi in my example you back it down to match your nozzle. You would turn down the unloader until it was matching, in our example 1000 psi. It was explained to me why you would want to do that, and I know this is going to sound moronic, but I can't remember exactly why. I am not real strong in the mechanics of a pressure washer.

[Richard 17]

We __only___ use split nozzle guns. We can adjust pressure as we go, depending on each individual circumstance. Agreed there realy is only cedar or pt spruce used in our area. We start off slow and increase pressure as required.

I'm to lazy to go back to find out who posted "I've only changed the pump oil once". Remember, OIL is cheaper than metal.

Love this site. There's always things to learn.

I figuered it was time I added my 2cents worth.

[PLD 14]

While the basic premise of using the unloader to control pressure is not a great idea, it's actually fine to turn down the unloader to match the pressure of your output. You will not lose any flow.

Example: You use a number ten nozzle to achieve your pressure, say 1000 psi. Using a pressure guage, you can back off the unloader until the pressure begins to fall below 1000 psi, then just turn it back up a quarter turn.

Ken,

I completely understand what you are saying, but I cannot understand why you would do this. The unloader is like a circuit breaker. If it is set for 1000 psi, it does nothing until 1000 psi, then it opens. If the nozzle you are using generates a line pressure of 1000 psi, it makes no difference if your unloader is set at 1100psi or 5000psi. In both cases, the unloader will sit closed.

[James 625]

JUst get a machine that puts out 4 gallons at 2500 psi. a 40 tip and a varible speed wand. You control every thing. From drooling to throwing up !!

I have by passes with regard to my hot water machines. Let it run all day,