sentences:  Criticism of NeSSI mechanical systems have included higher initial cost, inability to troubleshoot at a component level (due to compact/intensive spacing), and the lack of performance data associated with the use of elastomeric seals in long term installations.From a design perspective, it may be difficult to design a modular, mechanical system which meets the needs of the diverse process applications found in industry.Development of the NeSSI-bus has been an iterative exercise and it will need the close cooperation of both component and analyzer manufacturers to make their equipment NeSSI-bus compliant.