Low psi unloader adjustment

tcolborg

tcolborg

New member
So being still new to this I need some help. I picked up a pressure gauge to test what I was getting out of my machine. It is a water dragon skid, 3500psi @ 5.6gpm. I connected it to the high pressure line right before it goes in to the reel. I was getting about 2000psi through 150ft of hose with a 0 5.5gpm nozzle. When I let off the gauge would jump to about 3500. I tried to adjust the unloader, but when doing so the pressure on trigger didn't change. However, the pressure off trigger jumped up to 4500. Not sure if I am missing something on this. I just tightened the nut on top of the spring on unloader.

Am I not doing it correctly?
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Look at your bypass line turn it until you have a trickle of water coming out.It looks like your gonna damage something soon that unloader looks cranked way down to me.I would put the pressure gauge on the pump its self.
 
Kiloman said:
Look at your bypass line turn it until you have a trickle of water coming out.It looks like your gonna damage something soon that unloader looks cranked way down to me.I would put the pressure gauge on the pump its self.
Click to expand...

That's pretty close to what it was when I got the equipment brand new from Bill at power wash store.

What does loosening the bypass line do?

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you can screw the pressure gauge in at the alternate inlet of that unloader..
..just remove the hex-plug there in front of you.
E-mail me for a free copy of the unloader install and adjustment instructions.. free
..Do It Your Selfer's need a technical guy.
:{)
 
Sirocco Jerry said:
you can screw the pressure gauge in at the alternate inlet of that unloader..
..just remove the hex-plug there in front of you.
E-mail me for a free copy of the unloader install and adjustment instructions.. free
..Do It Your Selfer's need a technical guy.
:{)
Click to expand...

So, is the best place to get an accurate reading from a gauge is by installing it right on the unloader itself? I ask this because when a gauge is attached inline with the quick connect type,.and using a short whip line you get a normal spike pressure,..but if you attach the gauge at the end of 150' of hose the spike pressure seems to go to a higher number. Not just the spread between pressure and spike pressure,...but the spike PSI itself goes up from the short hose reading to the 150' hose reading??

Jeff
 
814jeffw said:
So, is the best place to get an accurate reading from a gauge is by installing it right on the unloader itself? I ask this because when a gauge is attached inline with the quick connect type,.and using a short whip line you get a normal spike pressure,..but if you attach the gauge at the end of 150' of hose the spike pressure seems to go to a higher number. Not just the spread between pressure and spike pressure,...but the spike PSI itself goes up from the short hose reading to the 150' hose reading??



Jeff
Click to expand...

I think the pressure is higher at the end of the line because of all the water behind it slamming to a stop.
 
Thanks Tom,..should I be concerned about this? Considering the spike with 150' of hose goes to around 3500-3700 PSI. The working pressure is at around 2700. The spike is way over the limit. That's why I'm wondering how much hose should be used when setting the unloader or if the gauge needs attached directly to the unloader as suggested above.

If I try to set the unloader with 150' of hose, I can't get a satisfactory working pressure if I'm trying to minimize the spike to the accepted range of around 300 PSI??

Can't find the happy spot,Ha,Ha,..

Jeff
 
814jeffw said:
Thanks Tom,..should I be concerned about this? Considering the spike with 150' of hose goes to around 3500-3700 PSI. The working pressure is at around 2700. The spike is way over the limit. That's why I'm wondering how much hose should be used when setting the unloader or if the gauge needs attached directly to the unloader as suggested above.

If I try to set the unloader with 150' of hose, I can't get a satisfactory working pressure if I'm trying to minimize the spike to the accepted range of around 300 PSI??

Can't find the happy spot,Ha,Ha,..

Jeff
Click to expand...

This makes sense and is exactly the battle I am fighting.

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Sirocco Jerry said:
you can screw the pressure gauge in at the alternate inlet of that unloader..
..just remove the hex-plug there in front of you.
E-mail me for a free copy of the unloader install and adjustment instructions.. free
..Do It Your Selfer's need a technical guy.
:{)
Click to expand...

Jerry I would love some instructions on this. You could email them to me at tristan@thewashsquad.com.

Thanks for the help.

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there should be a pressure gauge at the hose reel too !
..Ty s right.. inertia of he water-mass is the answer to many a blown hose.
And a lot of systems should have a regulating relief at the hose reel.
 
From what I see through my searches is predominately gauges being mounted at or very near the pump. I think if these people would check their spike pressure after 150'-200' of hose they'd be surprised in the rise of PSI,..near the 4000 PSI mark. I guess the moral is to just have good hoses,Ha,Ha,..

* Does the spike we see after 200' of hose stop at the unloader, or does it transfer to the pump? My guess is it's stopped at the unloader??
I only have one gauge, the QC type. I could screw it out of the QC and then into the pump head and check it.

Should've never bought a gauge,Ha,Ha,...

Jeff
 
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The head pressure at the pump is the one to go by. I think the hoses have always been seeing that extra pressure .
 
tomtucson said:
The head pressure at the pump is the one to go by. I think the hoses have always been seeing that extra pressure .
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Thanks again Tom, that is what I've concluded as well. And also explains why getting good flow and pressure with proper spike pressure at the end of 150' of hose seems impossible. I was beginning to over think the whole thing,..Ha,Ha,

**By the way, I bought the Giant orange spring unloader that you mentioned in another thread,..and I really like it so far,..very smooth unloading as you said. Also nice and hefty,..I plumbed it in through a block because its weight.

Jeff
 
For guys that have pressure-actuated unloaders..
the outlet check-valve in the unloader keeps the pressure from getting back to the pump,
But.. the heater, and the hose see all the added stress, of that "shock-wave" bouncing back, from the end of the hose.
..and if you run the full 200 degr. or better.. hose ends are easily popped.
..that's why I have a redundant pressure-relief on the INlets of my heaters,
..and recommend a regulating relief, (the more accurate one,) at the hose reel.
This "lops-off" the additional pressure spike, and reduces the unwanted stress against the whole system.
..but it's sometimes hard to get most peoples' heads around "Long-Term-Low-Cost" ..so we don't sell many.
..I just automatically give them to the guys buying one of our mega-systems with bunches of hose :{)
 
By cranking down the unloader you have changed the point at which it goes into bypass to 4500 psi and you will be putting extra stress on the pump. The unloader really does nothing to build pressure it just regulates the point at which it goes into bypass. the unloader should be set to unload at 3500 psi and you can usually go about 10% over rated pressure for a spike (approx. 3850 in this case) the reduced pressure at the nozzle can be caused by many factors, first of all being restriction like the hose length and size (1/2" vs 3/8 for example). The gun can also cause restriction which may be an issue as well, too small of a internal valve will restrict flow and reduce pressure. Chemical injectors will also reduce flow and cause restriction. Ultimately the pressure is regulated by the nozzle though the restrictions in the line will reduce the flow but the nozzle size determines the actual operating pressure (based on the pressure setting on the unloder). With the length of hose you may need to drop to a # 5 nozzle or be sure the one you have is new. You may also want to check that the throttle is up all the way.

As for where to put the gauge, if you put it on the head of the pump you will be able to get pump head pressure. Right after the unloader will tell you where the unloader is set to bypass the shorter the hose the more accurate the reading will be. you will notice the farther you go away from the pump the lower the pressure will get due to restriction and friction. Now if you can get 3500 psi on the pump operating normally and only 2500 after the unloader with all the items the same your unloader may be bypassing more water than it should and should checked for debris or potentially replaced.
 
Regulating Relief Valve

A regulating relief is as it's name.. think of it as an unloader without the unload function..
..just a regulator. Adjustable with accuracy, but just a regulator.

A pop-off valve, I as it's name.. a relief which "pops-off" when it releases..
..Accuracy is not the point. "dumping" all pressure is.
 
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