Higher GPM PW's

[Littlefield 65]

Alan, thanks for the enlightenment. I see I was wrong again. :) I thought I had the flow/pressure thing figured out, but was not taking into account unloader type. Also, with wood restoration, all my efforts have been toward increasing flow and reducing pressure, I didn't realize I could reduce flow by dropping the orifice size. Obvious now that you point it out...

[Dale 16]

Some of this stuff still confuses me..can you damage your pump if you use a tip that puts out more pressure than your pump is rated for?....

[R. Williamson 14]

Dale you will not damage your pump as long as the unloader is set for the max PSI the pump is designed for.

Robert Williamson

[Atlantic Power Washing 14]

Sometimes it is necessary to reduce the water flow, one example for me is when I clean foundations for builders that have already put mulch in around the house, it still takes a lot of pressure to remove the mud from the foundation but if you keep the flow at 8 GPM it would blow the mulch everywhere. When it comes time for me to rinse the driveways and sidewalks I switch to a # 20 tip, my flow goes up and pressure drops down, now I’m not blowing the pee out of everything….. Also when cleaning decks a high flow will damage the wood. It takes a certain amount of pressure to clean the wood but if you meet that pressure requirement at 8 GPM it will splinter the wood. I like to use about 1,800 to 2,000 PSI @ 4 or 5 GPM. One last example, if your removing gum and you still want your high pressure, but very, very HOT water, you have to sometimes reduce the flow, so here you would go to a smaller tip size.

I think of it like this, a # 4 tip will only allow so much water to flow thru it, the more water that flows thru it, the higher the pressure. Your pump will not push 8 GPM thru a # 4 tip unless it is like a 7,000 PSI pump.

If you have an 8 GPM pump, the pump is always going to pump a full 8 GPM at full throttle. If you reduce the tip size the extra water has to go somewhere, it goes into bypass.( pressure type unloader only)

Forgive me if I made absolutely no since…It’s too early in the morning....... :coffee:

[Guest rfitz]

Also when cleaning decks a high flow will damage the wood. It takes a certain amount of pressure to clean the wood but if you meet that pressure requirement at 8 GPM it will splinter the wood. I like to use about 1,800 to 2,000 PSI @ 4 or 5 GPM.

I would disagree with this statement, actually just the opposite happens,

less flow and more pressure do more damage to the wood, more volume and less pressure is best for wood, and I personnally never use more than 1200 PSI for wood, and even that seems high, I like more of between 750-1000 PSI, if you are using the right chems, you shouldnt ever have to go above this, and also, I hardly ever have any furring on my decks with this pressure,

but more importantly, is the fact is I use a potassium hydroxide based stripper as opposed to a sodium hydroxide based product, it strips just as well, and you wont get furring, one thing I learned with any type of wood is washing several times at lower PSI will get you much better results, as opposed to only washing/stripping once with strong chems, before I strip any wood, I use a good alkali soap and weak bleach solution, this in return makes the stripper work just on the sealers, not the mold, dirt etc.. therefore using a much milder stripper

[Aaron Ochsner 14]

I agree Rob, water & chems clean, not pressure(on wood at least). The reason we are buying higher volume machines is exactly because of that. So Rob are you pre-washing before stripping? Is that what I am hearing? I think I heard James mention something like that on another board....? It seems like extra time to me...........I am curious how you can use a more dilute stripper, on already wet wood/failed finish? Do you have to increase your dwell time because of the dilution? I understand the point of the stripper actually working on the finish only, just curious about the effectiveness of what seems to be a very low chemical dilution. Would you use this on a hard to strip product? Or use full strength, on dry substrate? Also please explain what you meant by potas/hydrox not felting the wood when stripping? I have used both sodium and potassium hydrox, and have noticed mild felting with both. This is only on Cedar or Redwood though, I have never had felting occur on PT.

Cheers,

Aaron

:yoda:

[Guest rfitz]

Hey Aaron,

I mix my own solution of potassium hydroxide, sodium metascillate, and sodium percab, I just play with the mixture until I get my desired results,

but when you actually pre wash with alkali and chlorine maybe 4 or 5 to 1 on the chlorine, and 6136 it is a soap Bob at pressuretek.com sells I mix that maybe 20 or 30 to 1 and apply, and amazingly with that mixture, you will strip off maybe 25-50% of the stain/sealer along with dirt mold etc.., then I come back with my stripper mix I mentioned earlier, apply on wet wood dwell, 20-45 minutes and the remaining stain/sealer just melts off, then if needed I will apply my Oxilic or citrolic acid, I actually learned this by accident, I was washing houses only that had decks, and when my house washing mix would sit on the deck to long, I would notice it would actually take off the finish, so now I pre wet the decks with water if I am only doing house washes,

Now you might think doing a deck twice takes longer, but when you have no sanding to do when you come back, you actually break even, if not better, because now I dont spend the extra cash on sanding pads, sanders, etc..

if you do get a touch of furring on the softer woods like cedar etc.. you can just take a pool brush, after you finish the deck and just lightly brush the areas, that furred and the stuff comes off like saw dust...

Hope this helps

[Mike Williamson 198]

I've got a flow type unloader, and I use various sized tips regularly....my gpm stays constant, my psi is what changes. Maybe I have a unique flow unloader, but I've never heard anyone on any of the boards mention not using tip size to regulate psi...If I want 3000psi, I use a 6.5 tip...If I want a lower psi, I use the corresponding larger tip to drop psi....the same amount of water is passing through the tip, just as a different psi. Am I not understanding the question here?

[Aplus 525]

There are two ways to lower pressure. The first is to use a dual lance wand. The second is to change nozzles.

I use a #9 25 degree nozzle for deck cleaning. It provides about 4 gpm at about 750psi.

Here is a nozzle chart. Study it carefully and you will figure out how to use it.

[One Tough Pressure 580]

Originally posted by oneness

I've got a flow type unloader, and I use various sized tips regularly....my gpm stays constant, my psi is what changes. Maybe I have a unique flow unloader, but I've never heard anyone on any of the boards mention not using tip size to regulate psi...If I want 3000psi, I use a 6.5 tip...If I want a lower psi, I use the corresponding larger tip to drop psi....the same amount of water is passing through the tip, just as a different psi. Am I not understanding the question here?

Bigger tips equal less pressure, and smaller tips equal less gpm. That can not be applied to all machines as they need the correct type of unloader to perform this.

High psi and less volume can be as useful as low psi, and high volume. Just depends on the situation.

[R. Williamson 14]

When you change to a larger orifice your PSI drops the GPM remains the same. When you change to a smaller orifice your GPM drops and the PSI remains the same. Because the extra water that will not flow through the nozzle is bypassed.

A flow type is a complete different animal. You can go up but cannot go down. That is when like Alan has said you have to bypass the water with a valve back to your inlet. Hope I said this correctly.

Robert Williamson

[Atlantic Power Washing 14]

Bigger tips equal less pressure, and smaller tips equal less gpm. That can not be applied to all machines as they need the correct type of unloader to perform this.

High psi and less volume can be as useful as low psi, and high volume. Just depends on the situation.

Can i get an AMEN?:D

[Paul B. 523]

Envirospec states in their catalog that the K-7 and K-5 flow type unloaders do not allow an operator to downsize high pressure nozzles, because it senses flow. Reducing the flow at the nozzle causes the unloader to cycle repeatedly. These flow type unloaders should also NOT be used with weep type guns, as leaks will cause it to cycle.

[Mike Williamson 198]

Ahh, I gotcha! I was missing that you were talking about using SMALLER tips than the machine required for max gpm/psi.

You're saying this will not work with a flow type unloader? Wish it would....there are a couple accounts I have that I could do just as well with a good bit lower gpm, and I have to haul water, so it would save me trips to fill the tank.

[One Tough Pressure 580]

Mike,

I know the feeling. I plan to add a bypass valve soon, just waiting on a reply from the distrib.

If adding one of these, you should have an adjustable thermostat, or else you will get steam, and may do some damage.

When I get the info, I will pass it along.

[Jon 533]

Alan I always run in by-pass mode, so much that when I do feel like washing my car or truck I forget and end up with a tank full of soapy water!

Makes a lot of sense to run by-pass as it also keeps the pump cooler.

[JustMe 14]

So when in bypass mode you can not use a downstreamer or upstreamer? I'm confused :)

[Jon 533]

I did not say that!

IF you are going to use either before you start your engine move the valve to regular mode so the chemicals do not go back to the tanks.

That is what happens with me, I keep forgetting to shut down and move it back so whatever I am running ends up in the tanks.

Now to explain why I seldom use up or down stream, I use a Shur-Flo pump to apply my chemicals from a 35 gallon chemical tank.

When I used to get the bug to clean our vehicles I would apply the soap forgetting to take it out of by-pass. Simply little mistake till you see all the foam in your 220 gallon tank!

Hey the tank needed to be cleaned anyway. LOL

[R. Williamson 14]

Ron, When you upstream and you return the bypass into the tank and do not have a on/off valve you will get soap in your feed tank, because you are injecting chemical into the inlet side of the pump.

When you downstream this is not a issue, because you are injecting chemical on the high pressure side not the intake side. When the pump is in the bypass mode it does not pull chemical.

Robert Williamson

[One Tough Pressure 580]

When I decided to run my bypass back to the tank, I got the idea from you Jon. Remember those pics I was snapping of your trailer?

I too, have forgot and upstreamed with the valve in the wrong spot, nothing better than a 230 gallon tank of pink suds.

I recently acquired a small cold water unit that I will use to wash the cars with now. Nothing fancy, but it beats the garden hose. I actually wanted to use it for a chemical pump, but do not want to cart the thing around and have a seperate tank to feed it with.

[Guest rfitz]

I am curious as to why anyone would want to upstream their chems, as opposed to down streaming, ? you get the same ratio, with no chance of chems going back into water tank, and you wont do any damage to your pump with downstreaming, someone please explain the advantages..???

[Atlantic Power Washing 14]

I have ran into a similar problem...I have a 5 gallon tank that is hooked to a 3 way valve. If you turn it one way it pulls from the 225 gallon tank, turn it the other way and it pulls from the 5 gallon tank...I keep antifreeze in the 5 gallon tank so that when I’m done at the end of the day all I have to do is flip the valve and it will run antifreeze thru the system......The problem I run into is, a lot of times I forget to open the trigger on the gun, so when I start the pressure washer, it goes into bypass immediately, and before I realize my mistake, it pulls all my antifreeze into the larger tank, because that is where the bypass water goes..

[Atlantic Power Washing 14]

Rob......i think some people use high pressure soap for fleet cleaning, they use chemicals that are safe to run thru the pump.....Never make the mistake of running chlorine thru your pump as i'm sure most of you know this..i made the mistake myself and ended up replacing the pump.

[One Tough Pressure 580]

I run upstream when I am using the surface cleaner. Won't operate under pressure from the downstreamer.

Ratio's are different on the US and DS. US is before the pump and the pump will only do the max it is rated for. which in my case 5.5. On the DS, it will do the 5.5, plus the soap, since the soap is added to what already came out of the pump.

I always run the machine much longer for rinsing than I do for chem applications, so it gets a really good rinse.

Except for the pool floater in my reclaim tank, I do not run chlorine in my cleaning applications.

[Atlantic Power Washing 14]

Alan...why not just put the chemicals down with a regular gun and then switch to your surface cleaner?