Pressure testing for buffer tanks

[kronic]

Does anyone out there know where I can get my new pressure vessel (buffer tank) tested? I have asked a couple of companies without any joy. Not sure where Gravity got theirs tested. Might have to e-mail WJ.

Dave

[maddox]

Pressure testing for buffer tanks

... I tought everybody knew that answer.

The tanks for Gravity are prototypes, and are tested and approved by me.As the ram (and a whole lot of other stuff going around in the RW community)

Now, the buffers and cylinders I made are prototypes, so no CE marking needed.
Disadvantage.. they may only be used in Robot.

[mute]

Pressure testing for buffer tanks

As far as I was aware PED applies to all pressure vessels that are made commercially, prototype or not. A pressure vessel is still a pressure vessel.

At 70BarG for volumes of:

Below 1 Litre - Sound Engineering Practice applies, No CE mark required
Above 1 Litre - Cat 1 applies, CE Mark is required
Above 3 Litre - Cat 2 applies, CE Mark is required and an approved notified body must be appointed.

When the pressure rises, the volume for Cat 2 falls so Cat 2 kicks in earlier (at 100Bar working pressure, Cat 2 volume drops to 2.5 Litre)

[m2xt]

Pressure testing for buffer tanks

My understanding here is that the PED applies to all pressure vessels with the only loop hole being prototypes. As long as the component is suitable identified see FRA build rule 8.15 and is not available for sale then this may meet the PED requirements. I do stand to be corrected because the PED is not easy reading.

As for pressure testing, I would expect that to be conducted by an establishment who have the necessary credentials to undertake the pressure testing to a recognised procedure / standard.

Daniel, I do not have my copy of the PED here but respect your classification as you are in that business, where did you obtain that classification list from?

As for Mario making prototypes, I would assume that as soon as 2 or more identical components are made for different customers than I would guess it would not be unreasonable to consider these are being manufactured for retail purposes.

Paul

[maddox]

Pressure testing for buffer tanks

The prototypes have all different set ups, and different dimensions. Also, Only Gravities Buffertanks are above the 1 litre mark.
But after the prototypes arrive with the tester I cant see how Im capable to keep m there.

Now, I have the tools, and the knowledge to make safe testings, and can approve prototypes.And use more than the standard procedure.
Daniel says it beautifully.
Below 1 Litre - Sound Engineering Practice applies, No CE mark required.

When going to a institute or firm that can make official pressure tests for non conform pressure vessels. ... I believe my cheapest quote ever was around the 500‚ mark, for each tank.

Now for people wanting to avoid this kind of cost. The prototype loophole I use is about the only trick in the book.Even rebuilding a CO2 storage bottle-removing the valve and placing an adaptor warrants retesting.

What Fireman Pete(and me ) did at the S7 wars. Uptubing some bottles(removing valve and bend the diptube)is also a reason for retesting.

Now the test for a conform CO2 storage vessel, with a PED licence is a lot cheaper.But not always applicable for us roboteers.

[mute]

Pressure testing for buffer tanks

As far as I understand the only time PED does not apply is when the item is manufactured by yourself (or your company) and used by yourself (or your company). As soon as it leaves your possesion via retail or gift then PED should apply. Prototypes cannot exist if they are sold as it then becomes a product. Prototypes are for your own personal use.

Take Gravitys ram at 100*180, that should fall into Cat 1 and carry a CE mark as its volume is about 1.4 litres (assuming my calcs are right). You know its good enough for the job and so do I but it still falls into Cat 1.

Please dont think this is a personal attack on you Mario, but we have to be really careful with this type of thing. If these things are not intended for your personal use then PED should apply. PED is unfortunately law and as I understand it there is no simple way of bypassing it.

If things are kept simple, and volumes are kept small then only S.E.P. will apply with little or no PED involvement. At a guess Id say that Cat 1 shouldnt be too much of a problem even with a CE mark, but Id stay well clear of the Cat 2 stuff (something like 150 bore x 180 travel). When we sell our equipment we always issue a statement with it saying that we have evaluated it under PED and then state which catagory it fits into, but this is usually for S.E.P. and Cat 1 stuff. Cat 2 & 3 are more involving.

If I am wrong please feel free to correct me because as Paul says, PED is hard reading so I may have misunderstood it, but from what I understand PED must apply to anything that is not intended for your own personal use.

[m2xt]

Pressure testing for buffer tanks

I was hoping to avoid getting into the PED and hands up, chose to find an easy way out. The easy way out I felt was to use Article 2 paragraph 3:

3. At trade fairs, exhibitions, demonstrations, etc., Member States shall not prevent the showing of pressure equipment or assemblies as defined in Article 1 not in conformity with the provisions of this Directive, provided that a visible sign clearly indicates their non-conformity and their non-availability for sale until brought into conformity by the manufacturer or by his authorized representative established within the Community. During demonstrations, appropriate safety measures shall be taken in accordance with any requirements laid down by the competent authority of the Member State concerned in order to ensure the safety of persons.

Daniel, as someone who uses the PED, you may be well placed to help us out here. You refer to categories based on volume but is there not more to it that just volume. My understanding is that CO2 is a group 2 liquid which leads us to Table 3 in annex 2 for vessels. I can see the 1L limit here but you can also apply the Bar L as well. We run at a maximum of 69 Bar which gives us a maximum volume of 2.9L (using 200 Bar L max limit). If this is the case, then a 140mm bore x 180 stroke ram would be under this limit which happens to be the largest case I have heard of to date. So, if we can keep the Bar L of all components below 200, i.e volumes below 2.9L, then SEP can apply and not PED

What do you think?

Paul

[mute]

Pressure testing for buffer tanks

Its the non-availability for sale bit that is worrying me... PED is in full effect once something gets sold.

When I ran my calcs I treated it as a gas at 70 barG. How do we treat CO2? Is it liquid, gas or both?

In a ram Id guess its mostly gas and Id guess the same for a buffer tank too. Usually when we run our units through PED we always have to take the worst case. Id say CO2 is not a stable liquid like water or hydraulic fluid so personally I think it should be treated as a gas, which sadly means doom and gloom...

Any thoughts?

[m2xt]

Pressure testing for buffer tanks

Daniel, I cannot find where the PED is in full effect for vessels that fall below the Bar L limit. In fact the PED goes as far as to say that the equipment must not bear a CE mark.

Good point about liquid v gas, the extinguisher is already specifically covered and must be considered at least as a cat 3. Outside of the extinguisher, a vessel is unlikely to become full of liquid but perhaps could be assumed as mostly gas. The PED does not appear to treat gas differently to a liquid, not as far as I can see at this stage.

Looks like I was reading the wrong table, the max limit for the Bar L is in fact 50 Bar L and not 200 as I first thought.

Are you going to Worthing? If so, we could be really sad and discuss further if I bring a copy of the PED. Did I really just say this!

Paul

[fwsorg]

Pressure testing for buffer tanks

I think I need to pick up some bits from you Paul which Im not meant to know about ). The above has confused me severely. I am building a buffer tank for my FP feather setup so once the questions have been resolved it would be good to know what I am obliged to do to make it road worthy.

[jeremy_cuss]

Pressure testing for buffer tanks

The cut-point that I use at work is 250 bar-litres. We dont register pressure vessels below this level. That may, or may not help this discussion.

Is it possible to get a design/prototype registered, and then multiple copies made and sold without further testing? If so, we have a potential manufacturer in Mario, and a potential salesman in Paul. There is probably a demand for 20+ high pressure buffer tanks.

Of course it needs to weigh significantly less than a CO2 bottle. A single size might be slightly restrictive, but no more so than the myriad RW rules to which we all conform already.

Jeremy

[maddox]

Pressure testing for buffer tanks

Im confident that my stuff is safe to use, if the users abide the restictions I put upon the stuff. Like always with the 1000psi Relief valve.And only in the robot(except testing,as a free mounted system).
No use after the tanks are damaged in the wars, so no dents or nicks.
Rams have a bigger safetyfactor, and small repairs are possible.If done by a competent person(and preferably me)

The parts are tested at 135 bar, about double the useable pressure in RW.

I know, normaly all the laws must be abided, but as the law gives us the escape route of the prototype please dont dish this in advance.

Testing for salepurposes in Belgiun is very expensive and very restricted. NO welded tanks for use above 30 bar.Bolted tanks are only acceptable for steam purpose.Not gasstorage.
If tanks are tested, 2 prototypes are nessecary, 1 for destruction testing, this series of tests costs 750‚ for a small tank. The other tank is for rntgen and long term test purproses, and this series of tests costs 500‚.
And even then it isnt garantied to pass the PED CE tests.
Is robot wars not expensive enough?

[big_nipper]

Pressure testing for buffer tanks


Emm, now you know why people use low pressure stuff.

[mute]

Pressure testing for buffer tanks

Paul, shouldnt have said full effect, you are right below the Bar-L limit only S.E.P. applies which is outside of PED. Sorry! Thatll teach me for typing while watching TV!

Ill see you at worthing... with coffee and a laptop... :sad:

[tunna]

Pressure testing for buffer tanks

I have just constructed a 0.9litre aluminium
buffer tank,from a fire extinguisher , it will be teseted locally just as a fire extinguisher would be tested,same type of test, water type ,it
will then be stamped,