While programmable controls and computers provide a great degree of convenience, unless these controls can be shown to conform to strict standards for the use of programmable devices in safety systems, it is preferable to use hard-wired connections for the critical alarm and analyzer malfunction signals.
Where programmable devices are used, it is important to ensure that they can not experience unintentional or unauthorized changes in program that might interfere with the safety of the process, and that they revert to a fail-safe condition should they experience a fault condition.
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