Video - 3/8" hose v 1/2" hose

Steven Button

Steven Button

Administrator
I got a 100' section of 1/2" pressure hose today and thought I would shoot a quick video to show comparison in performance. It's short and simple - I'm not a technical guy, so any comments are welcome as to the pressure difference or suggestions on how to avoid the over 1000psi pressure loss I am seeing in total.

The video is a bit shaky, but the gauge read 1700psi with the 3/8" hose and 1900psi with the 1/2" hose.

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When you run the water through the heater coil its just like adding more hose.That unit you have has a 660,00 btu burner with about 168 feet of coil.So if you bypass the coil you will have more pressure and get better draw because the water is not flowing as far.Nice videos.Hydrotek should have put a 30hp kohlor on that machine and got all the good out of that pump.Thats a 660 cat capable of 10 gpms a 3000 psi.Do you like the 1/2 inch hose better and where did you get it?
 
Thanks for the info Hal - I didn't realize that was the length of the coil, that woul account for some loss along with the fittings, 1-4" trigger gun outlet and 3/8" hose on surface cleaner...

Not tested the hose out yet, we've got 2 centers to wash tonight, so I'll see if quality and production is any different.

Got the hose from pressure washer products in Clearwater, FL.
 
I think 1000 psi loss through the coil would be high, but I don't really know what pressure drop should be for the coil. But like kilo said bypass the coil and see what the difference is.

Question - if you run the pump with no hose just spray out of the coil, and you read the pressure gauge at the pump, is that the 'back pressure' or pressure loss through the coil?
 
Steve get rid of the trigger gun! I know you will feel the difference.
 
Ran the pump with pressure gauge after unloader (bypassed coil), 4' jumper hose from unloader and I am reading 2600psi. Second gauge coming from pump outlet reads around 3100psi - I believe this is running pressure. But how would I tell if it is back pressure?

So it would appear that around 400 psi is being lost at unloader, another 400 or so at he coil (I tested pressure from unloader with 100' 1/2" hose) and the rest from restrictions at fittings, etc.

Russ J, Paul K, Jerry, Greg... Is this kind of loss normal at unloader and coil?

Thanks!!
 
offdutyfireman said:
How much water are you bypassing when you used the 4' jumper hose?
Click to expand...

... damn, I didn't know to check that. William what should I be seeing? My understanding is that a little should always be bypassing, no? If there is too much, do you think I have a problem with the unloader?
 
To get max flow and pressure we take off the downstreamer, get rid of all unnecessary elbows, adapters etc. Lose the trigger gun and use a ball valve instead. Crank up the unloader to bypass very little if it doesn't overwork your pump. (Get a balance) Try different pressure tip sizes to fine tune pressure. I love the ceramic tips. You will be surprised at the different performance.
 
+1 Kemp.
Steven , did you ever measured the flow at the gun/wand? Are you sure you are getting 8.5GPM ? What's the pressure at max flow and what size of nozzle you use?
I have similar hydrotek unit as you have and you need at least 5/8 bypass hose and actually "dual feed" a pump larger than 5 GPM. You don't want to go hard your pump and destroy seals.You don't want to have ANY flow restrictions.The pressure loss should not be more than 200-220 Psi (per 100 feet) on 3/8 hose and 40 Psi on 1/2...
I think Russ can confirm this....
 
I'm always suspect of the unloader when there's a problem.
 
Flow restrictors after the pump

Flow restrictions:

18" dia. heater-coil, of 1/2" sch 80 pipe , shouldn't restrict more than 200-300 psi with 8gpm. (I believe)

Those steel fittings can close-up to hundreds of psi restriction,
Yeah, go stainless.. if you can afford a $30 tee, ... otherwise, toss'em every 8 years or so,
and put new $6 ones back in.
Hose-ends can be en aMAAzing flow restictor..
starting at about 1/4" i.d. and rusting down to 1/8" i.d. = BIG restriction.
If you try to drill'em out.. be CAREful ! ..and wear safety-glasses !
drill bit shatter when trying that !

A downstream chemical injector is CraaZY flow restriction..
I've posted several times in here about that..
use the ST-52 variable-venturi injector, IF you "need" to leave one in-line..
opening the venturi relieves a lot of the restriction whilst yer not usin' it.

IF the ST-5 Flow-Switch has been overheated:
the plastic end-cap in the end of the magnetic slider.. can melt out, and go floating in to the coil.
It will usually NOT go all the way through, but will get stuck..
..THAT is a bad day. :{/
A slight overheat melts it just enough to release the little brass pegs that keep it from being a flow-restrictor in a bigger way.
OK here's 2 problems..
the little brass pegs get stuck in your trigger-gun,
and the magnetic slider in the flow switch butts-up-against the end of the flow-switch shell,
..allowing just a 3/16" opening to restrict closer to 1000 psi at your heater.
Remove the flow switch, check the magnetic slider for damage, or wear on those little brass pegs.
As the pegs are worn,as they bash-it-to the end of the flow-swich..
the end cap wears away, allowing the worn pegs to tunnel in enough to allow the slider to block the thorofare.
 
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I normally will bypass the coil if I am not running heat, plus I have 1/2 inch hose on all the surface cleaners and no gun handles, I run it straight into my ball valve. You will be surprised at how much more pressure u will achive doing these few things.
 
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