Pressure washer?

[Frank GorseParticipant @frankgorse]

I keep seeing adverts for a miracle cleaning device that seems to produce pressure washer performance from an ordinary hosepipe. The brand name on the latest one is ‘Jetsono’

Obviously this fits neatly into the too-good-to-be-true category but can anybody explain what the catch is. Or better still tell me that it really is as good as claimed and I should get one.

[peak4Participant @peak4]

When I searched the name, the first hit was a Reddit post linking to Trustpilot reviews
Several of the 1* reviews don’t seem to have tried the product, but do read the ones which refer to a Paypal experience/claim.
https://uk.trustpilot.com/review/jetsono.com
Previously JetNozzle
https://uk.trustpilot.com/review/jetnozzle.com?page=6

That said, I do have one that cost me 50p from a local market second hand tool dealer.
It’s just a valve with a pipe, and a brass nozzle with a small hole in the end; two tips supplied, one with a round hole and the other with a saw cut.
Not really different to squeezing the end of a plastic hose pipe to change the spray pattern; I learned how to do that most effectively when I worked at a brewery 🙂 .

See also this item on Amazon

The dearer ones do seem to have a hosepipe style adjustable spray nozzle too

Bill

[Frank GorseParticipant @frankgorse]

Ah,as simple as that! Thanks. Looks like I need a pressure washer,as I suspected

[Frank Gorse]

On Frank Gorse Said:

Ah,as simple as that! Thanks. Looks like I need a pressure washer,as I suspected

Yes, if you need a pressure washer, then you’d be disappointed.
For years I used one of the better KEW ones, semi-pro with a bronze pump and cooled motor, which eventually died.
Not having as much need now, I picked up a refurbished Karcher from their official outlet;
No idea how they compare pricewise these days, and nothing like as well built as the KEW, but it seems to work OK.
If you time it right, I think the Lidl ones have a tow or three year warranty.

Bill

[HollowpointParticipant @hollowpoint]

If you are in the market for a pressure washer can I suggest that you stay away from Karcher. I’ve had 3 of them and they all broke. The pump and fittings are plastic and can’t withstand the pressure. All 3 cracked in the same place.

I now have a Nilfisk which was about the same price but has metal fittings. Much better. I’ve owned it about 15 years and only ever had to replace an o-ring on the hose.

[Clive Brown 1Participant @clivebrown1]

I replaced a broken Karcher with a Nilfisk. Well pleased. IIRC my choice was based on a “proper” induction motor at a reasonable price point. Having said that, my old Karcher had done plenty of work.

[noel shelleyParticipant @noelshelley55608]

If some clever bit of physics could generate pressure like that of a pressure washer why do good machines need a 3Hp motor ? The relationship of human power to 1Hp has been discussed ie about 1/10th. The cheap ones are all plastic and aren’t going to last long. At this time of year, a warning, NEVER LET IT FREEZE ! I’ve seen several expensive ones ruined this way, split bronze bodies and all. If there is a risk of freezing run 50/50 water antifreeze mix through the system when finished using it. Build your own – 3Hp motor and a CAT pump – won’t be cheap but will last a lifetime. Noel.

[Clive FosterParticipant @clivefoster55965]

Maybe its not impossibilum to generate extra pressure from a simple hose whilst retaining adequate flow.

In his Second Machinists Bedside Reader Guy Lautard describes the Haralson Hose End which was apparently had modest, but real, commercial success shortly after WW2. As Guy writes the story the man who made these was personal friend who was asked to make a prototype by a “mad scientist” type and subsequently took it into production. Guy is known to be pretty reliable in general and the story certainly suggests personal experience and the quoted capabilities don’t seem unreasonable.

According to the drawing in the book the important innards are 1 7/32″ long consisting of three stepped bores going down from 0.491″ at the input to 0.219″ at the output with 0.352″ in between. Given the “odd” dimensions, implying ± 0.001″ tolerances the relative diameter of the steps is quite important but the lengths less so as those are given in plain inch fractions i.e. 1/64″ ± 0.015″. The comments state that the inlet to each step and the outlet to the final step must be a sharp edge. Which implies that there is some sort of voter or chaotic motion going on in the water flow so as to get a higher flow rate than a simple 7/32′ hole would imply.

Guy says that the nozzle needs at least 45 psi water pressure to work properly. As his domestic pressure was to low to make it work well he took it down to the local fire station and they took an interest and hooked it up to a more suitable supply. He claims to have, briefly, put his hand in the jet about 2 ft from the nozzle and it felt like being hit by a bunch of needles.

Opinions?

Clive

PS Searching for Haralson Hose End drawing on Google gave a link to Googleapis.com with a drawing and short write up from someone who made one. Seems to be favourably impressed by the results which appear to be much better than a simple restriction. Picture of the thing in operation too. He only had 40 psi behind it and is convinced that it would go much better with more oomph.

[duncan webster 1Participant @duncanwebster1]

Dimensioned drawing https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://someonesdad1.github.io/hobbyutil/shop/nozzle.pdf&ved=2ahUKEwirx9ecr5iLAxXAT0EAHenbLp8QFnoECCAQAQ&usg=AOvVaw2oZR4HDZ6n29jtK7mFJSTD

But intuitively I’d expect a well rounded transition from hose ID to nozzle to work better. Step changes introduce pressure loss, which reduce final exit velocity. Multiple steps could work better than one.

[Clive FosterParticipant @clivefoster55965]

Duncan

Well found. Direct link to the google.apis file I found.

Don’t think rounded transitions to the step will work. Ages back I asked a guy who (ought) to know about such things and was told that sharp edges generate a turbulent energy transition that effectively reduces the impedance of the smaller bore after the step increasing velocity and water mass flow rate.

Presumably the high input pressure is needed to drive such effects.

Way beyond my pay (or maths) grade.

Clive

[Howard LewisParticipant @howardlewis46836]

Mains water pressure, in UK, is about 60 psi, (say 4 bar), restricting the flow with a small orifice will increase the speed of flow, but at a lower mass flow.

This is not going to provide the 1,000 bar or more delivered by a proper pressure washer, needed for the more difficult cleaning jobs, to accelerate the water.

As ever, you get what you pay for!

Howard

[duncan webster 1Participant @duncanwebster1]

Mains water pressure in UK depends on where you live. At my in-laws house the electric shower upstairs was prone to not working due to insufficient mains pressure. I stuck a pressure guage on the outside tap, even with no flow it only reached about 6 psi. The water board said they were only required to provide enough pressure to run taps, not showers.

[VicParticipant @vic]

I went with a Nilfisk as well. I’ve had mine about 15 years. I replaced the original plastic pressure hose with a Rubber one as it’s much easier (more flexible) to use.

I would advise getting at least a 140 bar pressure washer. I borrowed a Kärcher 110 bar unit before I got the Nilfisk. It did work for cleaning my patio but took much longer than the 140 bar Nilfisk .

[Grindstone CowboyParticipant @grindstonecowboy]

I had (possibly still do, somewhere on a shelf) a device called a Jet-X sprayer, I think Australian in origin. Very simple, and provided the same sort of pressure as putting your thumb over the end of the hose, but which had the advantage of a soap container and a three-way tap (soapy water – off – clean water). Worked well for washing the car, perfectly adequate for dislodging mud from under wheelarches, etc., and I was told by a bodywork specialist never to use a high-pressure (i.e. pumped) washer to clean a car as it forces water into places where water is better not to be.

Rob

[noel shelleyParticipant @noelshelley55608]

Anything above 70 bar will work, what few talk about the flow ! 3gals/Min (13L ) is a good flow and will work well – provided you have a good lance and nozzel. People who talk of 200 bar think they have a good machine BUT with out a good flow, I won’t be vulgar ! Noel.

[VicParticipant @vic]

One of the things I particularly like about my Nilfisk is the rotating nozzle. It’s the one in the middle in this video. It works extremely well. My pressure washer also came with a standard nozzle.

https://youtu.be/8GI235NghhY

 

[noel shelley]

On noel shelley Said:

Anything above 70 bar will work, what few talk about the flow ! 3gals/Min (13L ) is a good flow and will work well – provided you have a good lance and nozzel. People who talk of 200 bar think they have a good machine BUT with out a good flow, I won’t be vulgar ! Noel.

Really? My budget at the time was £200 and I couldn’t find anything over 9L a minute in that price range. Even if you spend double that now you’d be hard pressed to get much over 10 – 11L a minute?
I’m guessing the manufacturers have worked out that for average home use 110-180 bar at 10L a minute is more than adequate.

[noel shelleyParticipant @noelshelley55608]

The manufacturers have worked out that there are plenty of suckers out there who will pay under £100 for something that won’t last long ! I’m afraid £200 would not buy you a good one. Whats a good one ? 1500psi at 13L a min, 6 or7 Lper min is fine but it will take a while to do a job as the nozzle will be small and have  a narrow band.

I’ve had mine for over 30 years and have frightened my self by looking at what a new CAT pump would cost, JUST the pump is in the order of £1000, then there would be the unloader, 15M of 3/8″ pipe, the dual feed lance, and a 3Hp motor, 2 pulleys and a belt.

Last year an acquaintance bought a karcher, cost £1800, lasted 3 weeks !   Noel.

[Frank GorseParticipant @frankgorse]

Thanks everyone for your replies. I’ve heard ‘mixed’ reports about Karcher before. Somebody told me that ‘AVA’ are good,made in Norway and stocked by B&Q so may go and look at those tomorrow.

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