Abstract
The performance requirements for tyre polymers used on multiwheel capsules in pneumatic pipelines are given, and the physical properties to satisfy those requirements are examined. Diverse laboratory tests are available to measure physical properties; however, the testing of tyres in a realistic environment will be a more conclusive guide to performance, and some experimental experience in this is quoted. Some of the many design compromises enforced by the operating environment of the capsule are discussed. It is considered that more extensive operation will be needed to establish that the reliability and service life of the best polymers are sufficient for the commercial operation of long pipelines. (Author/publisher)