Following a brief review of the PED with Daniel and Adam from Team Mute, the current thinking is as follows for pressurised vessels in 1000 psi / 69 bar max robot applications:

1) A vessel with a volume equal to or less than 1 litre must be designed and manufactured in accordance with the sound manufacturing practice of the EU country of origin and be marked with the manufacturer.

Vessels with a capacity greater than 1 litre are treated in one of two ways:

2) If the volume (in litres) multiplied by the pressure (in Bars) is less than or equal to 50 Bar litres, then paragraph 1) above applies. For example: max woring pressure 16 bar, max volume 3.125 litres.

If the Bar Litres is greater than 50 but less than 200, the vessel requires a CE mark to Cat 1.
The prototype ruling may be a way around this CE Cat 1 requirement. I do not consider myself qualified to advise on this one but reading the text suggests that if you have to purchase the vessel from a manufacturer, then it should meet the PED requirements.

Regardless of any of the above, pressure testing / certification apply.

I would welcome any comments on this text.

Paul