English to Spanish Tech/Engineering Manufacturing

I am looking for the Spanish equivalent of the word "Doorpacker". Regrettably, I do not have a specific context, I am translating a despatch note from a company which manufactures flexitanks, which are special flexible bags to be put in containers so that they can transport liquids. The Doorpacker is a part of the flexitank, I guess, but I cannot find a good translation. Thanks a lot!

http://www.flexitank.es/es/flexitank.htm