1000psi PRV

[harry hills]

In any case, we're building Combat Machines. Not bumpercars or animated barbiedolls.

QFT

[Gasbot]

I think I'm banging my head against a wall here. Fail safes, removable links, power lights - pressure components that are suitable... anyone catch my drift?

Maddox10,

We are not building combat robots or bumper cars! We are building pressurized vessels & systems which are all designed to a maximum working pressure which is specified by a manufacturer. In 'your opinion' a 50 bar device is suitable for 69 bar (even if that pressure cannot be reached). The manufacturers maximum working pressure is 50 Bar, hence without any further information from the manufacturer (these are not home built devices we are talking about) we should surely assume that the maximum safe working pressure is also 50 Bar? (and we're not taking burst pressure here)

I do not have opinions when it comes to pressure components, I have a fact that there is a design pressure of X, a design temperature of Y and a test pressure of Z.

I designed my gas systems to 90 BarG, hence I can say that everything in my system excluding the CO2 bottles and pressure relief valve is designed to operate or have a safe working pressure of 90 BarG (the hoses, control valves and couplings are rated higher). I know for a fact that the components I manufactured have a safety factor of 4 due to the stress values I used when calculating the minimum shell thicknesses. I know for a fact that the hydro pressure test was successful on the system to a pressure of roughly 128 BarG for 1 hour.

Your opinions are only opinions and you are relying on the in built factor of safety used in the valves construction.

I remember when people thought it was acceptable to use 10 or 16 Bar rams at bottle pressure, along with the plastic tubing and push fittings. This is the same but to a lesser extent - even if 69 Barg cannot be reached.

Regardless of the above, the build rules say 50 BarG components (because 50 Bar is what the manufacturers rate them at) must be protected by a pressure relief device rated to 110% of the working pressure, or independently tested to 120% of the maximum system pressure, which with a 69 Bar relief valve fitted would be around 83 Bar - which I personally consider to be too low.

The gas system I put into Mute complies with the build rules - do you yours? Or is it just in your opinion that they do?

Perhaps the rules do need changing so that I can skim 2 or 3mm off the CO2 bottles (in 'my opinion' they're over rated anyway) and thin the other components down too I can throw more armour on then!

[maddox10]

If my former job qualification didn't allow me to test and rate pressure parts, I guess we'll have to close down about any European PWR nucleair reactor too, not to count all waste incinerator plants in Belgium, and quite a few in the Netherlands.

As I wrote, and you can get the information from Burkert too. The 50 bar WORKING pressure of the 5404 1/2BSP or NPT valve is dictated by the reliable working of the soleno¯d pilot. Not the pressure rating of the body.



People using any derivate or copy of the Gravity set-up, Gasbot says your stuff ain't safe and not allowed in the rules. I bow to his greatness, and ask humbly that you won't participate in events anymore and scrap your utterly unsafe machines or rebuild those with materials he deems safe.

[maddox10]

I think I'm banging my head against a wall here. Fail safes, removable links, power lights - pressure components that are suitable... anyone catch my drift?

No, I'm probably to stupid.

Maddox10,

We are not building combat robots or bumper cars! We are building pressurized vessels & systems which are all designed to a maximum working pressure which is specified by a manufacturer.

Probably there ain't a difference between working pressure and pressure rating.

In 'your opinion' a 50 bar device is suitable for 69 bar (even if that pressure cannot be reached). The manufacturers maximum working pressure is 50 Bar, hence without any further information from the manufacturer (these are not home built devices we are talking about) we should surely assume that the maximum safe working pressure is also 50 Bar? (and we're not taking burst pressure here)

My opinion is backed up by pressure tests done to get UK machine to participate in Battlebots.

I do not have opinions when it comes to pressure components, I have a fact that there is a design pressure of X, a design temperature of Y and a test pressure of Z.Your opinions are only opinions and you are relying on the in built factor of safety used in the valves construction.

Sorry that English ain't my motherlaguage (nor father). I should have used another word. Maybe that this semantism satisfies your thirst for accuracy.

To my knowledge a Burkert is overdesigned concerning pressure rating, for the job it does.

I designed my gas systems to 90 BarG, hence I can say that everything in my system excluding the CO2 bottles and pressure relief valve is designed to operate or have a safe working pressure of 90 BarG (the hoses, control valves and couplings are rated higher). I know for a fact that the components I manufactured have a safety factor of 4 due to the stress values I used when calculating the minimum shell thicknesses. I know for a fact that the hydro pressure test was successful on the system to a pressure of roughly 128 BarG for 1 hour.

Tough as Nails has had active pressure tests at 130 bar with nitrogen.

I remember when people thought it was acceptable to use 10 or 16 Bar rams at bottle pressure, along with the plastic tubing and push fittings. This is the same but to a lesser extent - even if 69 Barg cannot be reached.

Those we still have. I just hope we can inform those people before they hurt themselfs.

Regardless of the above, the build rules say 50 BarG components (because 50 Bar is what the manufacturers rate them at) must be protected by a pressure relief device rated to 110% of the working pressure, or independently tested to 120% of the maximum system pressure, which with a 69 Bar relief valve fitted would be around 83 Bar - which I personally consider to be too low.

The gas system I put into Mute complies with the build rules - do you yours? Or is it just in your opinion that they do?

Yes they do. After consulting with event organisers and some other knowledgable people. yes.

9.7 Rating
All pneumatic components used with pressures greater than 50psi (3.4bar) must be rated/ tested to at least
the maximum pressure available in that part of the system. You may be required to provide documentation/
certification to support this.

I can produce the pressure test results of the systems I did build. All can stand hydrostatic pressure testing @1500 psi.

Perhaps the rules do need changing so that I can skim 2 or 3mm off the CO2 bottles (in 'my opinion' they're over rated anyway) and thin the other components down too I can throw more armour on then!

1.5mm from a 6mm wall. It will still stand the normal pressure. But the 3000psi burst disk could be stronger than the wall then.
Oh well, if you want to gain those few 100 grams that way. Sorry, but I would buy a smaller battery, or one with a better chemistry, like LiFePo4.

9.3 Cylinders
The compressed gas shall be stored in a commercially manufactured gas cylinder of appropriate design,
specification and certification. Except where the maximum storage pressure is less than 50psi (3.4bar).
Some events may have further restrictions on bottle sizes/ weights used, please contact the event organiser
for clarification.

[Gasbot]

With regards to your job you must have provided paper work or certification to your clients to prove that the work was safe and components suitable for the task? And we too have done work for nuclear, power plants, petrochemical, refineries, oil rigs, aerospace, etc all over the world - we've even got kit in space We always provide paperwork and certification which sometimes is worth more than the actual equipment we are selling.

I seriously doubt that burket will give you any certification for any pressure above the 50 bar quoted as it won't be in their interest. If you can get the proof then great, if not then 50 bar is surely the maximum working pressure? This is what I've been banging on about - if it ain't rated, then get them tested. Its simple, quick and easy. Or de-rate, its not as if its a lot of pressure that would be lost. It wouldn't even effect the performance.

Oh by the way, I was joking about skimming the bottles... I ain't that daft or desperate. And commercially available isn't exactly and issue, whether its affordable or not for anyone to buy is a different story.

May be the FRA needs to comment on this matter as I see it as a safety issue with repercussions for insurance?

[maddox10]

With regards to your job you must have provided paper work or certification to your clients to prove that the work was safe and components suitable for the task? And we too have done work for nuclear, power plants, petrochemical, refineries, oil rigs, aerospace, etc all over the world - we've even got kit in space We always provide paperwork and certification which sometimes is worth more than the actual equipment we are selling.

Previous job unfortunatly. Now I'm just a glorified but better payed greasemonkey.

I seriously doubt that burket will give you any certification for any pressure above the 50 bar quoted as it won't be in their interest. If

Exact the reason why Burkert states working pressure, not pressure rating. Imagine if an overzealous young engineer overlooks working pressure and goes for the pressure rating to desing a system. Great, but if over 50 bar, it won't work.

you can get the proof then great, if not then 50 bar is surely the maximum working pressure? This is what I've been banging on about - if it ain't rated, then get them tested. Its simple, quick and easy. Or de-rate, its not as if its a lot of pressure that would be lost. It wouldn't even effect the performance.

I'll ask the guy who did the original tests way back.

Oh by the way, I was joking about skimming the bottles... I ain't that daft or desperate. And commercially available isn't exactly and issue, whether its affordable or not for anyone to buy is a different story.

Skimming bottles, perfectly acceptable in my opinion, if done well.
But not for bottles that get banged/mechanicaly handled around after every fight, and have to cope with huge pressure and temperature differences.

May be the FRA needs to comment on this matter as I see it as a safety issue with repercussions for insurance?

In short, if the FRA says the Burkert 5404 is safe to use, it's ok for you?

[Gasbot]

Yep I've no problem at all - if certified for 50 bar. Failing that each one should be tested in accordance with the rules.

[Laser]

I can only see the point in prv's if you use LP and it has to be downstream of the regulator.
IMO the point of having a prv in full pressure or if the bottle and reg arent directly connected is pointless.
In full pressure the components are all rated at the pressure of what the co2 in the main tank is, and you cant get any higher pressure because you can only use co2 and heaters are forbidden.

[kane]

The pressure relief device is a safety device included to prevent the system pressure exceeding the limits that have been set by our rules. This ensures both fair play and a measurable limit at which the pneumatics can be set. Robots already demonstrate a very high level of power from pneumatics system and the last thing we want is Robots thrown through the roof into the public, as impressive as that would be.

Do not confuse Pressure Relief Device with Pressure Relief Valve. 1000psi burst discs are available that would meet the requirements. However we recommend a Valve as these are self resetting.

The ultimate solution is to run a low pressure system and directly attach the regulator to the bottle removing the requirement for the high pressure Pressure Relief Device.

9.8 Pressure Relief Device
A certified pressure relief device must be installed in each part of the pneumatics system where a different
operating pressure is used (operating pressures separated by a pressure regulating device).
9.8.1 Rating
Pressure relief devices must have a rating of 1000psi (68bar) or 110% of the pneumatic component with
the lowest €žmaximum working pressure. rating protected by that particular pressure relief device,
whichever is the lower.
9.8.2 Low Pressure Systems
Pneumatic systems employing pressures less than 50psi or systems employing air compressors that
have a maximum output pressure lower than the pneumatic component with the lowest €žmaximum
working pressure. do not require a pressure relief device.
The pressure relief device(s) dictate the maximum pressure available in that part of the pneumatics
system. The pressure relief device(s) must have a flow rate capacity that exceeds the maximum flow
rate that can be expected under €žover pressure. conditions. Any attempt to falsify the pressure settings of
pressure relief device(s) will be considered as gross misconduct by the FRA and may result in expulsion.
9.8.3 Full Pressure Systems
Non-regulated pneumatic systems or pneumatic systems where the regulator is not directly attached to
the gas cylinder require that a 1000psi pressure relief device is fitted.
9.8.4 Regulated Systems
Regulated pneumatic systems that operate at less than 235psi (16bar) and where the regulator is
directly attached to the gas cylinder do not require a 1000psi pressure relief device before the
regulator. The regulator must be rated to 120% of the gas bottle burst disc pressure. A pressure relief
device is required down-stream of the regulator rated at 110% of the component with the lowest
'maximum working pressure' rating.
9.9 Pressure Relief Devices
Pressure relief devices should be readily accessible and must be removable for testing purposes.

[maddox10]

In short, as long nobody overfills and heats the CO2 storage bottle, a 1000psi rated setup will be perfectly safe- pressure technical-, even without 1000psi pressure relief device.

As the rules changed over the years, to the detriment of pneumatic machines (Oh woo betide the machines build to 2003 rules for series 7, consumables.... please of gas-options. No more nitrogen, helium or simular. No, only CO2 and 1000psi Compressed air, thank you) and the advantage for hydraulics (from 3000 psi to 10000psi... woha, funny bit, only people with deep pockets or extensive hydraulic knowledge can benefit.).

Also, the failures on pneumatic machines I have seen, and experienced myself weren't pressure related, but speed and mass.
The decoupled Gravity setup (from it's ancestor Hammerhead II) removed that point of failure for most builders.

In short, is the Burkert 5404 valve, if used properly in a FP setup unsafe or not?