Preliminary evaluation of compressed air membrane dryers for exhibit case desiccation

Abstract

An exhibition case displaying ancient bronzes was found to have a high leak-rate and was subject to a variety of environmental factors. Because of the original case design, passive means of control were not proving effective. A simple, low-output (below 28l.min^?1) drying system based on hollow fibre (polysulfone) technology was tested and installed in the case to maintain the microenvironment below 43% relative humidity (RH). The membrane was tested below industrially-specified pressure parameters (less than 4 bar) and found to produce a range of consistent RH outputs suited to museum use. After some years in service, the system has proved reliable and simple to operate; optimum performance was achieved with more continuous operation.