Containment Tanks & Bags

Holscot are World leaders in the development of FEP Tanks and Diaphragms for Liquid Containment and Expulsion. Our exclusive Fluoropolymer processing experience facilitates innovative constructions with proven use in space.

Proud exhibitors at the Space Propulsion Exhibition 2022. Estoril, Portugal 9-13 May.

FEP Bladders and Diaphragms for containment of Space Propellants

Elastomeric diaphragms have been used as a means by which to completely expel propellant liquids from the propulsion tanks. 

However, the use of more aggressive propellant fluids such as Hydrogen Peroxide, MON and the green propellants,


conversely the need for zero chemical interactions with the ambition to use H2O for propulsion, has forced tank providers to look elsewhere for a more compatible material. 


FEP has proven itself to be that material, initially used by NASA for the first moon exploration missions.  


  • Inert to virtually all known chemicals and solvents, the use of FEP as a chemically resistant material has been recognised for years.
  • FEP has shown itself flexible and resilient enough to withstand cycling well beyond what is required of it in service.


As well as being considered as a stand-alone diaphragm, Space Propellant tank manufacturers have looked for a way to achieve complete containment of the liquid by using a FEP bladder

The most widely used design of the bladder allows the lower part of the bladder to be secured in the base of the tank while the upper diaphragm collapses and pushes the contents out of the tank. 

The construction of the bladder is based around two vacuum formings of equal size and shape welded together at the equator to form a flange which can be used to secure the bladder to the supporting tank. 


Additional features can be incorporated into the FEP Bladder including welded ribs to encourage expulsion of the contents, welded beads on the rim of the flange to provide location, outlet nozzles to allow connectivity to associated systems and even a breather tube to allow extraction of trapped gasses. Other designs of collapsible bladder are also possible including lozenge shapes with longer body sections and two formed caps welded at each end.


Holscot has been involved in dozens of projects over many decades involving bladders and diaphragms of different sizes and configurations,  used in micro satellites up to the largest vacuum forming in FEP ever achieved. 

This forming was used on the ATV tanks for transporting potable water to the ISS.  More details can be seen at our Case Histories section.

Why Holscot?

  • Proven manufacture and project management / collaboration experience
  • Access to Holscot proprietary in-house manufacturing techniques and expert engineers
  • World leaders in providing Fluoropolymer solutions, with 50+ years experience

Tell us about your project by completing the contact form below or email to get in touch.

See our Case Studies & Blog Posts for more information, & connect on LinkedIn

Case Study

MT Aerospace

In order to provide the astronauts on the International Space Station with vital supplies, the European space ferry ATV (Automated Transfer Vehicle) is launched...

View Case Study