GPM versus PSI in Cleaning Applications

[Larry Cobb]

We have been researching the Impact of Truckmount & Portable pump systems.

In talking with Spraying Systems engineers, the importance of GPM over pressure has been clarified.

Impact is more dependent on GPM than PSI.

If you double GPM. the Impact goes up 100%.

If you double the PSI the Impact goes up 41%

We have noticed this dramatically on rotary jet Tile & Grout cleaning.

The top rated T&G equipment (Turbo Hybrid) has two 0502 jets (total of #4).

On a TM, changing to two 0503 Jets will increase the impact to 150%.

Try this out on a tough T&G cleaning job.

We also like a minimum of #8 or #10 in total jet size on 14" wands.

Pressure hose diameter does become a factor with long hose runs.

 

[Lee Stockwell]

Arlen Knight and Bill Hachtmann had a great demonstration of this in 1982 at a road show in Atlanta that Kleenrite shared.

It involved moving trays of sand at a constant speed under jet with various volume and pressure setting to simulate impact variables.

 

[Cleanworks]

It would be good to get some comparisons with portable machines as there has been a shift to smaller jets and higher pressure pumps over the last decade or so. Most machines used to use a 5 or 6 flow at 100-500 psi. Now we commonly see machines with a 2-3 flow, probably because the heater can't keep with a higher flow. So what's more effective? A 2 flow with heat or a 4 flow with tap hot water?

 

[Larry Cobb]

It would be good to get some comparisons with portable machines as there has been a shift to smaller jets and higher pressure pumps over the last decade or so. Most machines used to use a 5 or 6 flow at 100-500 psi. Now we commonly see machines with a 2-3 flow, probably because the heater can't keep with a higher flow. So what's more effective? A 2 flow with heat or a 4 flow with tap hot water?

The #4 flow with hot tap water,

if all the electrical power is used for Vacuum & Pump power.

 

[jcooper]

So, generally... Instead of increasing pressure, use larger jets!

 

[clean image]

Larry, your assuming unrestricted energy requirements



Given finite power, such as a water otter, 15 amp, 1 would choose 1200psi and #4 over 550psi and #6


Although good food for thought,

 

[Giorgio]

If You up the jet size heat exchange machines won't maintain temp. My experience is best TnG cleaning results are achieved by using rocking chems, mechanical agitation and high temperature rinse.

If those three criteria have been properly satisfied then psi and flow are subordinate.

I suggest hi temp will out perform flow and psi consistently.

 

[Giorgio]

I notice grout damage can occur at psi 900 and up. At least the grout in my regain. If you slow down in one spot too long the psi can remove cementous material from the grout lines. Not to mention blast out actual chunks of loosely installed or cracked grout. Then, your looking around for all the little pieces to put back like a jigsaw puzzle hoping the homeowner doesn't notice. Lol. Has that ever happened to you?

 

[Giorgio]

Guessing I run psi at 500 or lower for higher temps and optimal results on TnG

 

[Cleanworks]

So, generally... Instead of increasing pressure, use larger jets!

You have to keep things in balance. There has to be a high enough flow to flush the soil and traffic lane cleaner from the carpets. There has to be enough pressure to loosen the soil from the carpets. Pressure is agitation. Then you have to have enough vacuum power to recover the solution. Heat always helps but not at the expense of pressure and flow.

 

[Giorgio]

Hi heat will melt chewing gum from carpet.

18 flow wand at 900 psi won't touch it.

But, if your going for quantity vs quality then hi flow and psi is definitely the way to go. :-)

 

[Russ T.]

Heat, flow, psi. Each is important and will change a bit from machine to machine to find the optimum performance. It's tough though, because running a rotary and then running a wand put different demands on the machine so that may require having different flows going through the tool. I think this is where a high quality truckmount comes in and delivers consistent heat without much care for flow.

Ideally with my machine, I'd uses short choppy strokes and allow the heat to BUILD. I use 6 flow on my 14" wand but am pretty compelled to try some bigger jets on the ol' Westpak. But that's just how my Cleanco is. It has the Max Heat option and how much water I'm spending will dictate wether it's putting out 200° or 245°.

Larry's numbers looked pretty interesting. I bet I will benefit by going to at least 8 flow.

Does anyone know what jets are set up on a new Devastator Wand?

 

[Larry Cobb]

Larry's numbers looked pretty interesting. I bet I will benefit by going to at least 8 flow.

Does anyone know what jets are set up on a new Devastator Wand?

Devastator has four #2 jets for a total of #8.

 

[Cleanworks]

Heat, flow, psi. Each is important and will change a bit from machine to machine to find the optimum performance. It's tough though, because running a rotary and then running a wand put different demands on the machine so that may require having different flows going through the tool. I think this is where a high quality truckmount comes in and delivers consistent heat without much care for flow.

Ideally with my machine, I'd uses short choppy strokes and allow the heat to BUILD. I use 6 flow on my 14" wand but am pretty compelled to try some bigger jets on the ol' Westpak. But that's just how my Cleanco is. It has the Max Heat option and how much water I'm spending will dictate wether it's putting out 200° or 245°.

Larry's numbers looked pretty interesting. I bet I will benefit by going to at least 8 flow.

Does anyone know what jets are set up on a new Devastator Wand?

I use a 6 flow on a 12 inch wand. It make sense to go up a little on a larger wand.

 

[Mikey P]

Tom's 8 flow ain't the same as other's 8 flow.

High psi is for lazy cleaners who want to skip pre scrubbing

 

[hogjowl]

So?

 

[ruff]

I agree with Larry. Done within reason, I found that the larger jets (say 02 versus 01) definitely improved the flushing and all in all cleaning results.
I did not take it past that and never tried 03. Anybody uses 03?

Mike, how's Tom's 8 flow different? Are you talking recovery ability or does it produce more gallons per minute?

George- smaller jets will not produce more heat on the carpet.

 

[Cleanworks]

Tom's 8 flow ain't the same as other's 8 flow.

High psi is for lazy cleaners who want to skip pre scrubbing

C'mon Mikey, turn that pressure up to 500 psi and see the difference.

 

[Jimmy L]

I'm really confused at this time. I didn't realize this could be so complicated.

 

[Bob Savage]

Both of our truckmounts use #14 flow - one wand at #6 flow, the other at #8 flow (dual wand setup).

Having our big LP heaters (230,000 BTU), we are never at a loss for heat to 2 wands, even in the depth of the Ohio winters. We have never turned our heater up past the middle setting on the dial using 2 wands at the same time, and still can melt chewing gum and candle wax with no added chemical.

It's nice to not ever have to worry about not enough heat for cleaning, and I agree a #6 flow should be your minimum standard flow rate in order to get enough flushing. More flow is better up to a certain point, that certain point being compromising your heat while cleaning. You will also need sufficient vacuum for recovering the waste water at the same rate as you are used to when cleaning with a lower flow rate.

 

[steve_64]

The bigger the jets the more fiber distortion you will get. At least in my experience. I'm using 1.5 because the .02 caused more distortion even at about 300 psi.

I run about 600 psi and it seams to be the sweet spot for heat too if I keep the trigger pulled enough.

I don't change the setup if I need to prescrub and if I need more flushing I just slow down the stroke.

 

[Cleanworks]

The amount of distortion you get sometimes depends on how close your jets are to the carpet. On my machine 12, I am using 4 1.5's and it works beautiful. The jets are angled to shear across the carpet fiber. I have a 2 inch westpack that has 4 02 jets that angle straight down and distort deep pile carpet. I feel if I could change the angle, it would work fine.

 

[Able 1]

George- smaller jets will not produce more heat on the carpet.

How do you figure? Every truck mount is different..

How I look at it, you go with the biggest jets that you can still maintain great heat with.. With my Peak the valve will pop pretty good in the summer and will cause heat distortion when going over a carpet a couple times trying to rinse something out with 6 flow, not so much with 9 flow.. My Apex would cause a LOT of heat distortion if I ran 6 flow wand.

We run 400 psi and I would rather flush stuff out with bigger jets then spray through the backing with small jets and higher psi and have my dry times sacrificed...

IMO 6 flow sucks as far as flushing the carpet, 9 flow has been a perfect balance for both of my truck mounts..

 

[Larry Cobb]

The amount of distortion you get sometimes depends on how close your jets are to the carpet. On my machine 12, I am using 4 1.5's and it works beautiful. The jets are angled to shear across the carpet fiber. I have a 2 inch westpack that has 4 02 jets that angle straight down and distort deep pile carpet. I feel if I could change the angle, it would work fine.

Devastator will let you change the jet angle with 2 fingers.

 

[hogjowl]

Yeah, but tighten it down with some pliers or it'll move on you.

 

[steve_64]

Just lift the wand higher to adjust spray pattern.

 

[Old Coastie]

My life is so uncomplicated. I just gotta work five times as hard.

 

[Goomer]

The amount of distortion you get sometimes depends on how close your jets are to the carpet. On my machine 12, I am using 4 1.5's and it works beautiful. The jets are angled to shear across the carpet fiber. I have a 2 inch westpack that has 4 02 jets that angle straight down and distort deep pile carpet. I feel if I could change the angle, it would work fine.

I agree...the effectiveness of PSI/GPM is relative to the distance between the jets and the surface being cleaned, so it is a big consideration.

Anyone who does pressure washing knows that it is the GPM, not the PSI that does most of the heavy lifting, and that at ? psi using an ? degree tip, there is a sweet spot in the distance to maintain the lance tip from the surface being cleaned to maximize cleaning effectiveness and minimize damage.

 

[Mikey P]

The bigger the jets the more fiber distortion you will get. At least in my experience. I'm using 1.5 because the .02 caused more distortion even at about 300 psi.

I run about 600 psi and it seams to be the sweet spot for heat too if I keep the trigger pulled enough.

I don't change the setup if I need to prescrub and if I need more flushing I just slow down the stroke.

No glide?

What wand?

 

[steve_64]

No glide?

What wand?

No glide prochem quad stainless old and heavy as fook.