Jetter unit fitting an unloader valve

[Munkul]

Anyone on here have experience with jetting units?

I've just bought a harben jetting unit. Its 275bar, 45lpm, with a yanmar 40hp diesel engine, hydraulic reel, proper bit of kit
Plan is to tart it up a bit then it'll go for hire for washing farm buildings out. Double quick like.

Anyway, its currently configured as a jetting set, with a manual pressure dump valve, and has a jetter style lance which dumps low pressure water when the trigger is released. It's ok, but everyone prefers a proper flow cutoff lance these days. That means I need to fit an unloader valve rated for the flow and pressure.

q1. I'm reasonably au fait with pressure pumps and unloaders. If I fit the unloader prior to the manual dump valve, so keep them both and have individual returns to tank, then i can have my cake and eat it? Ie, use a normal shutoff lance, AND keep the convenience of a dump valve for jetting drains? Or am I missing anything?

Q2. I've got experience with Speck Pumps and their adjustable regulator unloaders. We've built tech demo skids with 55lpm pumps and the UL262 valve, this gives us in effect adjustable flow as well as pressure. They can also be used to run multiple lances off a single pump, as they can work in pressure regulating mode when not fully unloading. I don't know how it works compared to a standard unloader, but it absolutely works, brilliant. The problem is, if I want one for my unit, it's £620 + vat. Owch.
Are there any cheaper alternatives that can run multiple lances? As it would be a huge benefit to my customers if it could run 2 lines at 22lpm at times.

 

[BrokenBiker]

@carbon might be the man that knows

 

[Turbo]

That pressure and flow will be too much for washing concrete. It will cut tracks in concrete instead.

I remember building a similar system for a bloke who was going to use it to strip plaster off old stone buildings.

It would not be a safe machine to hire so you will need yourself well covered insurance-wise.

You will need a very clever unloader to run two hoses. If one guy stops washing you don't want the other one suddenly getting the full output of the pump.
The Kew inplant system had a good unloader fitted but they were not cheap.

It's not a good idea for an unloader to be bypassing part of the flow all the time as it will wear a track in the internal valve seat. An unloader is designed to be fully open or fully closed. It is not a pressure adjuster.

If you want a lower pressure at your lance you either fit a bigger jet or throttle back the engine. Don't start screwing back the unloader unless you like fitting expensive service kits to them.

On any of our hire machines we removed the knob of the unloader and fitted locknuts loctited in place. If they can a hirer will mess with every knob or switch they can, especially farmers.

That massive flow rate will be impossible to feed with mains pressure. The hirer will likely resort to a slurry tanker full of murky water drawn from a lake or river. Fit a good inlet filter and expect to replace seals due to the pump running dry because of a blocked filter!

On one machine we built we fitted a float switch in the tank that cut the ignition on the petrol engine if the water got too low.

 

[Munkul]

All good points to consider.

I can play tunes with the working pressure by nozzle sizing, it may be a much better idea to run 200bar instead, that's what the guys run normally for washing chicken sheds. They already run 30lpm machines so 45lpm will be like turbo. Or maybe a small spraybar with two smaller nozzles would be better.

I know what you mean regarding the unloader. Conventional unloaders aren't designed for part flow, HOWEVER google the Speck Pumps UL262. It's specifically designed for that purpose, and like I say, it just works

Flow is an issue on some sites. My BIL does some of this work and he already uses my ifor trailer to pull around 2 full ibcs just for buffer. He may end up using this rig, and he'll be the one that I work with to get it usable.
The saving grace of the harben pump is that it's fully safe to run dry, it's got no seals that need lubricated. It can even run on sea water!

 

[carbon]

Yes you can fit an unloader, but as @Turbo suggests don’t use two lances unless you like changing repair kits or unloaders. I’m only on my phone but will check later on what’s available.

 

[carbon]

If I fit the unloader prior to the manual dump valve, so keep them both and have individual returns to tank, then i can have my cake and eat it? Ie, use a normal shutoff lance, AND keep the convenience of a dump valve for jetting drains? Or am I missing anything?

Ive worked on some jetters that have had the very same setup.

There are more options for unloader valves around the 200bar max pressure that are suitable for the flow rate you have, but they probably aren't going to be as durable as the speck UL262. Speck even produce the UL221/200 which is rated to 50l/min with max pressure of 200bar, but that would impact the unit if you wanted to use it as a jetter. Looking at the UL262/2 version from some of my suppliers I could possibly do you a better deal on the price

 

[Munkul]

perfect, thanks Carbon

I've had a quote off my local washer hardware people, they've quoted me a VB85 unloader at a great price, obviously not as good as Speck but it's easy to replace.

I'm going to run a single shutoff lance with a Suttner turbo nozzle sized for 250bar, now that'll do some real damage... hopefully! Pig muck is like concrete, it takes 2-3 goings over after detergent soak presently.