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I've been asked to investigate different styles of hydraulic valves for use by a customer.
One of the styles that has been discussed, I can't find any info on, not helped by no-one knowing what its called. So I'll describe it:
Imagine a length of rubber hose with fluid flowing through it. If you twist it (and constrain it correctly) it will twist tighter and tighter, restricting and finalling stopping flow, depending on the flexibility of the rubber and the viscosity etc of the fluid. A bit like making party balloon animal.
Apprently, they're used in the oil industry on surprisingly big pipes. Anyone know what I'm talking about?
Venturi?
Starfish Valve?
Is it a wind up?
cheers. Venturi is sort of the right direction, but they seem to be used more increase flow velocity than restricing it.
[i]Starfish Valve? [/i]
If only they were called tea towel holder valves 🙁
Needle flow control type? Knob actuated?
Inline flow control that's hexagonal shaped?
Inbuilt check valve? Pilot operated ?
Remote mounted or part of a valve stack?
I'll consult my Vickers / Rexroth literature but I've no idea what you mean.
What does it look like shape wise?
Viscosity control valve? Regulates flow in proportion to viscosity of the medium?
Venturis increase flow velocity with concurrent pressure drop.
Would it be a constrictor valve?
Like this? [url] 
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Would have posted it as an image but it's way too big.
Torsional mingegrip valve, made by Puxton and Thrump
constrictor valve is looking promising. I'll investigate further.
And can you believe I googled cheekyboy's suggestion without reading it properly...
Its a multi-slitted flange gusset valve surely?
constrictor was the word I thought off and there is some reference to them for use in catheters(!) but I couldn't see anything else.
peristaltic valve
hmm, its not really peristaltic, although that does involve necking a flexible tube.
I've done a very basic CAD model, just uploading an animation now...
I just asked the two oil and gas hydraulic engineers next to me and they both said "eh, do what? The hose will split!"
The hose will split!"
Nice assumption, given they don't know the hose material and size, the fluid pressure or in fact what the fluid is in this case...
Bloody engineers. Think they know everything.
I `ve worked on hydraulics in the past, mainly on systems on ships, one of the main properties of a hydraulic system is that the hydraulic medium is incompressible. Most hydraulic systems use rigid pipework where possible, flexible pipework is only fitted where necessary, flexible pipes are normally made up of several layers of rubber encasing a steel braid inner armour, this would make the action of twisting the pipe to create a restriction rather impractical and quite hard to do in terms of mechanical actuation, there are plenty of other methods of restricting flow commonly available.
I do recall an inline flow check valve fitted on warships that was adjusted by twisting the outer collar, this was however made of solid steel.
More than happy to learn something new if what you are asking for actually exists, keep us posted.
I know nothing much about valves, however, what you're describing put me in mind of an Iris like a camera shutter or indeed the human eye... googling "iris valve" looks like it might be what you're after:
[img] 
[/img]
Does anyone from the above thread live in the south central area of England?
I work for a PVC hose manufacturer, so I've no idea about the valves above (sorry) but in the next 6 to 12 months we will need a sales rep with this sort of fluid power experience who lives along the M4 corridor.
Email me in my profile name link if you're interested.
Iris valve it is.
For what its worth, the application I'm interested in is low pressure, low flow, moderatly high viscosity.
This is quite cool:
the plastic bag type ones look like they are aimed at solid materials.