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Pressure problem


SkulBlaker

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Hey guys, a mate of mine has bought the 50L purefreedom trolley and also bought 100m of 6mm micorbore.  When using the 8mm that was supplied with the trolley the pressure is fine but when changing over to the 6mm the pressure is garbage even with the controller set to max.  Any ideas? Can't see any leaks anywhere.

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Recalibrate the controller

press and hold the up and enter buttons at the same time

Increase the pressure

press enter

 

the smaller diametre hose probably needs more pressure to pump the water (pushing water through a smaller sized 'hole'

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52 minutes ago, SkulBlaker said:

Hey guys, a mate of mine has bought the 50L purefreedom trolley and also bought 100m of 6mm micorbore.  When using the 8mm that was supplied with the trolley the pressure is fine but when changing over to the 6mm the pressure is garbage even with the controller set to max.  Any ideas? Can't see any leaks anywhere.

 

You mean flow, not pressure.

Flow and pressure aren't the same although they are inter related.

 

6mm microbore hose is half the size of the 8mm hose and so will not allow the same flow rate. There was a discussion on this topic 2 or 3 months ago.

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tbh i'd stick to the 8mm,the 6mm will have a reduction of around 30% less flow and will increase hose wall resistance by a massive amount all that added up only means increased load on the pump and battery and both will fail early because of the smaller bore hose, those pf stystems are designed around the 8mm hose,don't change it

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At 88psi a 15mm straight steel pipe will support a water flow of nearly 17lpm. An 8mm (minibore sized hose) pipe will support a flow of 4.26lpm at 88psi and 6mm pipe (minibore size) will only support 1.68lpm at 88psi. Of course the longer the hose the slower the flow of water through it.

 

The other point to understand is that water can flow freely through a straight pipe with a smooth inside water fairly quickly. But there comes a point when it starts to become turbulent due to friction. It starts at the sides and this turbulence interrupts the follow and creates a restriction. This can be overcome to a certain extent by increasing the pressure but that uses more energy and probably self defeating.

Replace that smooth pipe with coiled plastic reinforced hose and you will get turbulence much sooner.

Edited by spruce
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13 minutes ago, spruce said:

At 88psi a 15mm pipe will support a water flow of nearly 17lpm. An 8mm (minibore sized hose) pipe will support a flow of 4.26lpm at 88psi and 6mm pipe (minibore size) will only support 1.68lpm at 88psi. Of course the longer the hose the slower the flow of water through it.

 

The other point to understand is that water can flow freely through a straight pipe with a smooth inside water fairly quickly. But there comes a point when it starts to become turbulent due to friction. It starts at the sides and this turbulence interrupts the follow and creates a restriction. This can be overcome to a certain extent by increasing the pressure but that uses more energy and probably self defeating.

Replace that smooth pipe with coiled plastic reinforced hose and you will get turbulence much sooner.

i did play with a laminar flow device to sort the wall resistance out spruce,it did help and maybe with a bit more tuning it would be an advantage in the wfp stystem.other projects took hold sooner than expected and i didn't take it further,when i find the time i might go back to it

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9 hours ago, kevinc250 said:

i did play with a laminar flow device to sort the wall resistance out spruce,it did help and maybe with a bit more tuning it would be an advantage in the wfp stystem.other projects took hold sooner than expected and i didn't take it further,when i find the time i might go back to it

 

I hold my hands up as I honestly don't understand all the dynamics that make up the relationship between pressure and flow. I did look at the topic when you mentioned it a while back but all this physics with Reynolds formula, pipe turbulence, velocity, fluid viscosity and amplification of perturbations arising from the inlet or from the roughness in the pipe inner wall surfaces or from the pipe vibrations was way above my head.

I once read somewhere that the turbulence generated in a straight hose is much less than in the same hose when coiled. This seems to make sense as I appear to have a better flow at the brush head when all the hose on my reel is uncoiled.

 

Steve Jones once experiemented with a much smaller bore size pole hose in the Aquadapter early days. I was asked to participate but excluded as I used a Shurflo pump and they were concerned that it would invalidate the pump's warranty. I don't know what the outcome was; I did ask Paul but he didn't reply. I never did see a smaller bore hose sold on their website so just presumed that what worked in theory didn't work in practice.

 

What about aerating or agitating the water flow to improve cleaning action at the brush head in the same way Jacuzzi's spa baths do? How would it effect rinsing off the glass?

Edited by spruce
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I have 100m 5mm pu hose on my reel. It's very light and nice to work with but it really does restrict flow. Max flow rate is 5 otherwise the pressure it builds up just to push through the hose causes it to dead end. I really like the weight so I would struggle to go up to 8mm but wouldn't go 5mm again.

 

Then again, I still get enough pressure to make it spray back off the glass...

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Have 100 meters of Blue Exceed and another 20meters on my slx (split SLX47) and have not as yet experienced any major issues since changing from 'mini-bore'. Love the lightness of the new hose.... 

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