Some simple pneumatic questions

[widow_twanky]

Nothing too taxing here and I probably know the answers anyway. Thought Id ask anyway just in case.

1) I have some 5/2 valves. I want some 3/2 valves. Is it a simple case of plugging the outlet and exhaust of the unused ports?

2) Are Trevors regulators used in any heavies? Do they generally have sufficient flow rates?

Andy

[maddox]

Some simple pneumatic questions

1) is no problem, but Woody has better ideas on this.

2) Obsidian used a Trevor, works like a charm, but yes, the low flowrate is something to observe.

[widow_twanky]

Some simple pneumatic questions

Bigger buffer tank then?

[woody]

Some simple pneumatic questions

Yes ...just block off the two unwanted ports OR if you want you can re-plumb the 5 port so that it has two common inlets ...two common outlets and one exhaust....this gets you a 3 port with double the flow ( outlet ) of the original 5 port.
Drawing available should you wish to go this strange route.

The main co2 tank valve has a low flow value, therefore any regulator attached to it cannot supply enough flow of gas to feed a decent sized ram....hence the use of a buffer.

Do you need a bigger buffer? See post below.

[woody]

Some simple pneumatic questions

The size of ram or cylinder used in a Flipper and the amount of energy that it could possibly deliver governs the maximum throw of a given mass....you cannot get more but you can get a lot less if your flipper mechanism and pneumatic system isnt matched correctly.

Acceleration, Velocity and Extension time equations follow for a given ram force and load.

Force to extend in Kg = 0.008 (constant) * (bore in mm) * (bore in mm) * (pressure in bar)

So let€™s take a cylinder with a 100mm bore and 200mm stroke @ 20 bar.

Ram Force = .008 * 100 * 100 * 20 = 1,600kgf

Mass to move = 100kg @ lets say a 4-1 ratio.

So the tip is taking 100 kg and moving it over a distance of four times the stroke ( 800 mm ) or 0.8 metre with a force of ...divide ram force of 1,600kg by the lift ratio of 4 ... 400kgf.

Acceleration = force in Newtons/mass to move

CONVERT Kgf TO NEWTON€™S (multiply by 9. = 400 x 9.8 = 3,920 Newton€™s of tip force.

So 3,920 Newton€™s /100 = 39.2 m/sec/sec...then take gravity in to account ...minus gravity 9.8 m/sec/sec = 29.4

Then calculate the velocity.

v = SQRT(2as)

Where a is the acceleration and s is the distance travelled.

v = SQRT ( 2 * 29.4 * 0.8 )= 6.8 m/sec ...this is a MAXIMUM velocity and no matter how you try you cannot get more ...only less.

Throw = v*v/2*Gravity

6.8 * 6.8/19.6 = 2.36 metres above the flipper tip.

Lets take this MAX velocity of 6.8 m/sec and calculate the ram extension time.

Solving for time t= V minus Vo /Accel = 6.8/29.4

Stroke Time (secs) = 0.23 second ..This is the quickest possible extension time for the given ram force and load.

You should now size your pneumatic system so as to keep a constant pressure under the piston and FILL this ram @ 20 bar in 0.23 sec.

Ram volume in cc (Convert ram dimensions to centimetres) = Radius * Radius * stroke * Pi.

5cm * 5cm * 20cm * 3.14 = 1,570 cc or 1.57 litres.

So to fill the ram in 0.23 of a second we must supply

1/0.23 * 1.57 litres of gas per second @ 20 bar = 6.82 litres per sec @ 20 bar.

We need this to be in litres per second @ 1 bar.. so multiply by your working pressure of 20... 136.4 Litres per second.


Cant be bothered with the Math?
Theres an embedded calc towards the bottom of my page.
http://www.teamonslaught.fsnet.co.uk/pneumatics.htmhttp://www.teamonslaught.fsnet.co.uk/pneumatics.htm

The embedded calc also outputs a Kv and Cv MAXIMUM value recommendation for your valve.

(Message edited by woody on October 26, 200

[widow_twanky]

Some simple pneumatic questions

Woody,

Id be interested in seeing a drawing of how you do that (I assume you just switch the inlet/outlet pipes round on one side). One of the big problems on Hydra is flow. Plenty of big pipes but lots of small orofice fittings, lots of T pieces, elbows and stuff. All seems to mean gas delivery is actually quite poor (12mm pipe into a 1/4 fitting means you get the flow through the 1/4 fitting and nowt more).

Andy

[Ianshock]

Some simple pneumatic questions

Hi Sorry to steel Andys thread but can you recommend anywhere for 3 way ball valves for FP ? Maelstroms (AKA St Agro) spool valves seriously sticking since my refurb !
(Thanks to these we didnt give Andys Hydra too much hard work to get thru yesterday fight !)
Cheers Ian

[woody]

Some simple pneumatic questions

Old archive pic link....

http://web.archive.org/web/20040814181807/http://www.teamonslaught.fsnet.co.uk/S5-2.gifhttp://web.archive.org/web/200408141....fsnet.co.uk/S 5-2.gif

[widow_twanky]

Some simple pneumatic questions

Yes we both seemed to have complete failures on the pneumatics in that one :blush:. Found out what our problem was. Someone (probably Paul cos it couldnt possibly be me ) forgot to screw down the speed controller so it was fouling the pipes and fitting........DOH!

Andy

[woody]

Some simple pneumatic questions

Ball valves.

http://www.yateson-stainless.com/yateson03.htmhttp://www.yateson-stainless.com/yateson03.htm

Scroll down the centre panel for some pdfs.

Watch out for the opening torque ratings for these ball valves ...youll need a DECENT actuating ram to get the valve to open QUICKLY!

http://www.valves-online.co.uk/acatalog/Three_Way_Ball_Valve.htmlhttp://www.valves-online.co.uk/acata...all_Valve.html

(Message edited by woody on October 26, 200

[woody]

Some simple pneumatic questions

Andy ...Use the calc on my page and get a guesstimation of your required flow rate for both your flipper and axe.
The ratio is simply the flipper tip travel divided by ram stroke or Axe head travel divide by ram stroke.
Some sort of a starting point is needed to refine your system.

[widow_twanky]

Some simple pneumatic questions

Will do Woody. Have already decided that it needs redoing. It never caused a problem before but as Lukes getting better at driving its become more apparent that we need to get more out of it.

Thanks

Andy

[widow_twanky]

Some simple pneumatic questions

Actually Woody, just had a look round that and its a fabulous little tool. Need to take some details of the geometary and then play with it a bit.

Andy

[supernova]

Some simple pneumatic questions

http://uk.youtube.com/watch?v=Bp9SWUoRxJchttp://uk.youtube.com/watch?v=Bp9SWUoRxJc

Theres a T port in there

got my one from valves online too.

[Mouldy]

Some simple pneumatic questions

looks good suren, tryed a self-righting test yet? wouldnt do it in the living room though lol