Class 9 won't burst at 100 psi. You can choose any diameter you like. You just need to work out what force you want at the tip of your arm and work back from there.

Only oils made for pneumatics should be used with compressed air.
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So even the rain that falls isn't actually going to fill our dams and our river systems

PVC takes a fair bit of pressure, just look at all those 2inch diameter spud cannons running on Start Ya B'tard. Only now and again do they blow the end apart.
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how much do the pet bottles weigh when fiberglassed and filled with air???

got some curiosity question regarding hydraulics. ive been poking around the net for some time but there isnt really that much info at all on the subject its all fairly vague...

atm my understanding of hydraulics is that youve got the pump motor powering the pump, that draws fluid from a resivour compresses it to the right pressure and then gets sent through valves to the actuator cylinder.. (not figuring in an accumulator).

my question is does the resivour store the hydraulic fluid unpressurised (if so wouldnt the volume of it have to be absolutely huge considering the massive working pressure of the system) or pressurised, in which case how do they fill the system up or depressurise it? a one way valve on steriods or some such?

its got me totally confused... and i really want to know how it all works lol
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It depends on what type of hydraulic system you are useing .Most hydraulic systems use a Prime mover (motor) powering a pump the pump is capable of reaching the high presures and flow volume needed for the whole system .The pump draws the fluid from the resivior and pushes it through the circute the circute on most hydraulics is an open flow through flow control valves on the main controls back to the resivior .When the presure is needed it is diverted through to the ram or hydraulic motors by a control valve .If it is to a ram the presure will act against the ram until the ram reaches its end stop
If the control valve is not shut at this point then the presure builds up until it opens an over presure by pass valve .This valve can be in the circute but is sometimes built into the hydraulic pump like in car power stering pumps .
The by pass valve is like a burst valve on a gas bottle its main function is to stop the system going over the maximum safe working presure ,it has to be big enough to take the full system volume and presure of the oil, the released presure is retuned back into the oil resivior .

Most hydraulic systems use an open flow circute . So high presure is only built up when flow is diverted to a ram or a hydraulic motor when the ram or motor isnt conected to the circute the presure and flow is at a much lower presure but at full flow this ensures that the prime mover isnt under constant load when it isnt needed , but instant power is available at any time .
Some hydraulic circutes use acumulators but this is usualy found in very high working presure systems that can have a variable load imposed on them such as large hydraulic rams controler roller feed pressure in sugar mills and other milling operations the main use of the acumulator is to keep a constant presure on a load but can also act as a fluid resivior in case a suden load acts against the ram like a log or rock going through the rollers which could push the ram back against the full presure and blow hydaulic hoses ect .
The acululators are usualy high presure gas filled bottles with a floating piston in them to keep the gas and oil seperate.

As oil is a non compresable liquid the power transmited is due to useing full displacement pumps (ie ) piston or gear pumps that take the liquid in one side and force it out the other to form a flow in a basicly open flow circute from the resivior to the pump back to the resivior .
Presure only builds up when the flow is interuped like when the flow is diverted into a ram or motor conected to a load ,unlike pheumatic systems where presure is built up by compresing a gas and storeing it under presure then releasing the presure into a ram or motor ect.so a huge resivior is not needed only enough oil to fill the circute any any rams that may be used need to have their volume calculated in the total resivor capacity.most hydraulic equipment use double acting rams so when presrue is acting on one side of the ram and as oil is being pumped in to the cylinder oil is also being displaced out of the low presure side of the cylinder back into the resivor.keeping the resivior at a fairly constant level .

Its bit more involved especialy if you start talking hydro static systems and such that use variable pumps then you need to start useing charge pumps and divert valves etc .
Most hydraulic systems have the resivor at normal atmospheric presure and are vented to alow the resivior to empty or fill depending on what is being used in the circute .
For hydrulic systems that need to work inverted or such then some sort of low presure acumilator is generaly used but it has to be built in such a way as to let the resivior displacement change with out alowing air to be drawn into the system .Air or gas presure in a hydraulic circute is dangerous and can also cause the hydraulic pump to cavitate causeing damage to the pump .

I hope i wasnt to long winded or technical for you

that was perfect the part i was going wrong with was that i was thinking of hydraulic as a compressible fluid thinking that youd need to have a completely collosal resivour to keep filling up the system as the pressure built up, but the power and pressure is trasnfered through the oil itself and youd only need to have enough to fill the system up.

i guess all that opens another question, if you where using an electric pump instead of an engine driven one would i be right in assuming that youd just turn on the pump as you needed the actuator to move? and then just use a single valve.
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problem with that is generally you need to pump into both sides of the cylinder, you need to pump into the back to push it forwards and into the front to push it backwards.
so valve still required, turning the pump off when not in use is still a good idea though.

basically all liquids are incompressible.
an "emergincy procedure" for hydraulics if you get a leak is to fill the system with water, it'll stuff everything up but hey if its your ass in the aeroplane you arent going to be worried by something rusting up.
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the hydrolic crusher down at work "seems" to work using only one pump with the piston on one side of the pump and tank on other side. the pump is a rotary pump (i think)
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It probably uses a return spring of some sort.

Since they can weigh 50 times or more the weight of what they are crushing, they can be designed to apply force over a large area.

When you look at the force vs area that a rubbish or car crusher applies in relation to its weight, you will probably find that your average robot is far more powerful relatively speaking.

It also has to try and crush something that weighs as much as the crusher does and is (hopefully) designed to be non-crushable. which makes life a lot harder for it.

Consequently, Combat Robot crushers are usually not crushers at all, but more "Penetrators". They focus the force into a small point, which hopefully will get through the armour and damage something inside, rather than literally flatten the other bot.

Because of this pointed penetration, the spiky bit of a "crusher" robot also needs a fair amount of force behinds its retraction, or it will quite likely get stuck.

Hence, the need for two-way rams and valves. The rubbish compactor might not need dual-acting rams, but you can bet the bull-dozer has them.
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For a single ram system with a double acting ram a system used on larger out board motors and power leg type boats could be used
.This consists of a rotary gear or vane type pump which has a reversable electric motor .Basicly this system does not use a resivior the oil is pumped from one side of the ram through the pump and into the other side of the ram .This would posibly be the best type of system to instal in a robot especialy if the pump was incoperated into the ram its self eliminating any hydraulic pipes .In most of these type systems when the ram reaches the end of its stroke the motor basicly just stalls out and trips a thermal breaker if left on when this condition is reached.
Some more sophisticated systems use a presure switch to cut power to the motor.

Just to explain a litle more on hydraulics, oil is a non compresable substance so the pump is basicly acting like a pinon in a rack and pinion gearing.

The oil is the rack so as the pinion (pump) is turned the rack (oil ) is pushed in one direction iff you put something like a ram in front of the rack it will do work as all the work load is directly conected to the pump the bigger the load the more power is needed to drive the pump .

(this is asumeing a perfect system with no presure leakage and fluid friction)

Pheumatics on the other hand require the compresion of a gas to high presure then the gas is released into a cylinderand expands to do work against a piston.

I am thinking of turning a 1kg dry powder fire extinguisher into a buffer tank for a pneumatic flipper run at 100psi but I have a couple of questions.
1/ What fittings do I need to connect a 1/2 inch tube to the tank? What size hole and what thread are used on the neck of the bottle? Remember that flow rate is the key to a good buffer.
2/ What is the best way to discharge a dry powder extinguisher?
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quote:

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Originally posted by kkeerroo:

1/ What fittings do I need to connect a 1/2 inch tube to the tank? What size hole and what thread are used on the neck of the bottle? Remember that flow rate is the key to a good buffer.

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quote:

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2/ What is the best way to discharge a dry powder extinguisher?

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quote:

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What is the best way to discharge a dry powder extinguisher?

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quote:

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Originally posted by DumHed:

If you're not going to use the valve at all I suggest hole sawing a piece of 6mm aluminium the right size to fit in the top of the bottle, and either welding or alloy brazing it in. You can then put whatever fitting you want in it.

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