Boring Flow Techie Stuff

[dgardner]

I posted this on another board, mainly to help the less experienced folks out there. Not sure if any of you seasoned vets can use it, but just in case, I'll post it here too.

First up is a standard nozzle flow chart. It seems every time I need a value, the charts out there don't list it. Maybe pressure on the chart jumps from 250 psi to 500, and I need 400, or it lists flow for a 25 jet and I'm looking for a 24. Anyway, I punched the flow calcs into a spreadsheet and did pressures every 50 psi from 50 to 800, and jets from 1 to 24. Like every other nozzle table, pressure is at the jet.

Last is a hand-drawn chart I did a while back to approximate flow from a jet (or jets) at the end of a 100 foot 1/4" hose. It overcomes the major limitation of the standard nozzle flow charts that don't take hose friction losses into account. It doesn't figure losses through the valve or wand plumbing, so your actual flow will be a little lower, but it is worlds closer to real life. The pressure here would be ATM with wand keyed and water flowing.

 

[Lee Stockwell]

Good job Dan!!

 

[dgardner]

Thanks, Lee.

The graph can show you lots of interesting things if you take the time to puzzle through it. For instance:

• The spot where the pressure lines cross the Y axis (vertcal line) is flow through a 100' open hose (no jet, just a hose with the end cut off). Look how close 24 flow is to an open hose!
  
  If you read straight down from the operating point, this tells you how much pressure is left at the jet. For instance, go straight down from 24 flow/600 psi and you cross the X axis at about 85 psi. That's the pressure at the jet with 600 ATM and 100' of hose. Amazing! (to me at least).
  
  The 02 flow line is nearly horizontal. This means flow is primarily controlled by the jet, whereas the 24 flow line is nearly vertical, meaning flow is primarily controlled by hose friction losses. The 24 jet does little to actually set the flow rate (with 1/4" hose anyway).
  
  The pressure lines get closer and closer together where they cross the Y axis, meaning that increasing pressure has a point of diminishing returns. At some point, increasing pressure will have little to no effect on flow.
  
  You can achieve identical flow rates while varying how hard you impact the fibers. For instance, you get almost the same exact gpm with the following combos: 06 flow/600 psi, 08/425, 10/340, 12/280, 16/240, 24/215 all get you around 2 gpm.
  
  Draw a line horizontally across the graph at your pump's rated gpm. Any jet/pressure combos below this line will work as expected, any above the line will not acheive the desired pressure. The point at which the flow line crosses the pump gpm line is the maximum pressure you will see.

 

[Mikey P]

Great!!

 

[Ron Werner]

Thats awesome information Dan.
Thanks

AAAAAAAAAAAAAAAAAAAAAAAAA

 

[Shane T]

Does water temperature have any significant effect on pressure? For example 150 degrees compared to 200 at the wand?

 

[dgardner]

I don't believe so, Shane.

 

[Delta Dave]

LOVE IT. So far I've spent about 3 hours with your chart. Just wanted you to know your work is appreciated.
Thanks Dan

David

 

[Lee Stockwell]

Welcome to MB Dave! You come from good people.

 

[Delta Dave]

Welcome to MB Dave! You come from good people.

Thanks Lee.

 

[Delta Dave]

So Dan am I getting this right? The x axis displays your jet pressure. As in 10 flow at 600 psi/atm, translates to approximately 290 psi at the jets?

 

[Duane Oxley]

Slight kink in the works...

PSI at the machine and PSI at the wand valve are different. Your chart is accurate, if you're talking PSI at the wand, which you'll need a gauge at the wand to verify.

From what I remember when I did a similar evaluation using 1/4" hose, there was about 1 PSI lost per foot of hose, so, at the end of 100, you'd lose 100 PSI, 200 ft. resulted in - 200 PSI, etc.

And if the hose in question is on a live reel and wound up, loss is even more.

If I recall (and I did this in 1997 or so, so I could be off a bit regarding specific figures), a live reel with 200 feet of 1/4" hose on it, caused a loss of about 250 PSI, using a #6 jet.

Interestingly, a 3/8" hose only lost 50 PSI. (But we didn't do that on a live reel.)

Bottom line: If you're using the system pressure gauge as the gauge of pressure, you'll need to compensate for that.

In addition, I suspect that a shell and coil exchanger (vs. a shell and tube), would cause additional loss.

 

[Louis]

Good stuff. printed and saved

 

[ayetti]

Chart ROCKS! it has been helping me a ton.

 

[Mikey P]

bump

 

[hogjowl]

What practical use does that information offer to a cleaner?

 

[dgardner]

I know this thread is extremely old. Shortly after I started it, I had a couple of deaths in the family that altered my priorities in life, and I never saw all the replies after Feb of 2011. I’m going to answer a couple of the old questions so those who find this thread with a search will have more complete information.

So Dan am I getting this right? The x axis displays your jet pressure. As in 10 flow at 600 psi/atm, translates to approximately 290 psi at the jets?

That’s exactly right DD, with one caveat: The pressure curves represent pressure at the machine while the wand is keyed (this is always a little different from static pressure with no water flowing). To use the 500 PSI curve for instance, you would key the wand and adjust the regulator for 500 while the water is flowing.

So yes, under the conditions you state, you would see approximately 290 PSI if you plumbed in a pressure gauge at the wand.

PSI at the machine and PSI at the wand valve are different. Your chart is accurate, if you're talking PSI at the wand, which you'll need a gauge at the wand to verify.

Interestingly, a 3/8" hose only lost 50 PSI.

Quite right Duane, the point of the chart was to approximate what happens at the wand (at the end of a 100’, ¼” line). And 3/8” hose has much lower loss than ¼” at typical carpet cleaning flows we use.

What practical use does that information offer to a cleaner?

Good question, Mr Sutley…

Say you were happy with the total amount of water your wand delivers to the carpet, but want a little more impact on the fibers (higher spray velocity). The second chart allows you to pick a new pressure/jetting that will deliver the same GPM, but at higher velocity. For instance, you run 08 flow at 425 PSI. If you switch to 06 flow and bump the pressure to 600, you will deliver the same gpm, but with more force. It works in reverse, too.

The chart can also help you validate your choices. For instance, if you run a porty with a 1.5 gpm/500psi pump and you want to run 06 flow, it ain’t gonna happen. The 06/500 point is above the 1.5 gpm line, showing that your pump won’t be able to keep up. If you follow the 06 flow line to the left to the point it intersects the 1.5 gpm line, we see that it falls between the 300 and 400 psi curves. So the pressure ATM will drop from 500 to around 370 psi when you key the wand, and reading straight down from there shows you’ll only have about 260 psi at the jet(s).

And once you know you will be running 260 psi and 06 jetting, the first table tells us that your combo will result in a 1.5 gpm flow, validating our conclusion that the pump will be operating right at its limit.

The top table was created primarily because I was frustrated by existing charts. They would have flow values for 400psi, for instance, and the next higher column would be 800, and I wanted flow at 500! – Grrrrrr….. so I did the calcs for every 50 psi to 800 and every flow from 1 to 24.

OK then, I can let this thread die peacefully (again), now that the questions are answered.

 

[mirf]

Thanks Dan.
Planning on sticking around?

 

[dgardner]

Thanks Dan.
Planning on sticking around?

Yup!

 

[Bob Savage]

Yup!

Dan-

Glad to see you back. So sorry to hear why you've been absent.

Sent from my DROID RAZR using Tapatalk

 

[dgardner]

Thanks Bob. What are you doing these days? Still manufacturing equipment?

 

[Bob Savage]

Thanks Bob. What are you doing these days? Still manufacturing equipment?

Still cleaning carpet, and just revamping my slide-in, and the ETM, but have retired from manufacturing.

Although my ETM is still working great, they are a hard sell to carpet cleaners.

I cannot find anything else for improvements on the ETM, other than the redesign inside the van to maximize space, and adding more fresh water on-board (total of 90 gallons - Astro van).

Sent from my DROID RAZR using Tapatalk

 

[GCCLee]

Bump for Tom Ingram

 

[Larry Cobb]

Good job, Dan .

Lots of pressure loss in just 100 ft. of typical solution hose.

A lot more loss @ 200 ft.

I always tell my TM users that they must increase pressure @ the TM to maintain a given flow with longer hoses.

Larry

 

[dgardner]

Lots of pressure loss in just 100 ft. of typical solution hose.

A lot more loss @ 200 ft.

I always tell my TM users that they must increase pressure @ the TM to maintain a given flow with longer hoses.

Good advice Larry. I wonder if they realize how much is really needed?

I did a quick comparison using a meager 10 flow wand running 400 psi at the machine, with a 100' hose run. To duplicate the same performance (gpm and pressure at the jet) for a 200 foot hose run they would have to increase pressure ATM from 400 to about 650 psi. It's worse for larger jetting, not as bad for smaller jets.

Leaving the pressure the same would result in about a 20% hit in gpm delivered to the carpet with the 200' run.

If you run a high flow wand and already run high pressure ATM, the pressures needed to maintain the same performance as you increase hose run quickly become astronomical.

 

[Lee Stockwell]

The only time I disagree with Dan is when I'm wrong...

 

[Mikey P]

Dan

I hope this is OK with you..

http://mikeysboard.com/how-to-predict-your-tool-flow-rates-by-dan-gardner/

 

[dgardner]

Very cool!