Foam insulation for a liquid oxygen densifier

Abstract

Analyses indicated that it would not be cost effective to vacuum insulate a 7 foot diameter by 30 foot long liquid nitrogen vessel for a launch facility liquid oxygen densifier. Foam insulation appeared to be the logical choice for this infrequently used ground support equipment but the history of foam problems due to cracking, adhesive failure and internal shearing weighed against the use of commercial spray-on material. These problems were solved with a system consisting of alternate sealing and flexible foam layers: (1) an inner membrane sealed to itself but not attached to the cold shell or pipe; (2) a flexible foam insulation layer; (3) a vapor-tight sealing membrane; (4) a second flexible foam insulation layer and (5) an outer aluminized sealing membrane. The second and subsequent layers are sealed to each underlying layer by flexible foam contact adhesive. The inner sealing membrane is particularly vital in that it allows the first foam layer to expand and contract as the tank temperature changes and it also protects the tank from chloride corrosion from the foam. This paper describes preliminary testing to prove out the system and the steps taken to install flexible foam insulation on the oxygen densifier vessel.