Power Transformer Conservator Tank- Rubber bag

Hello,

Regarding the rubber bag or air cell which is provided in the power transformer, can any one tel me how it is installed in the conservator tank

I have seen these rubber bag / air cell are being transported (non inflated) condition. My doubt is how is this bag inflated and how does it retain its shape inside the conservator.

Please help me to clear my doubt.

Regards,

Mayur