| abstract |
A casing 10 has inlet and outlet openings 11 and 12 which communicate with the ends respectively of a gas passage member 15 disposed within the casing 10. The member 15 is composed of two parts 29 and 30 which are secured together and which include respective recesses co-operating to define perforated tubular portions 16, 17 in the member 15. Both the casing 10 and the member 15 are made of plastics material, which may or may not have a fibre or particulate re-inforcement. <IMAGE> |