ABSTRACT
Figure 13.1 shows the same EUC as was used in Chapter 11. In this case, however, the additional protection is provided by means of additional K2 pilot valves, provided for each valve,V. This implies that failure of the valves,V, was (wrongly) not perceived to be significant. Closing the K2 pilot valve (via the PES and an I/P converter) has the same effect as closing the K1 pilot.The valve, ‘V’, is thus closed by either K1 or K2.This additional safety-related protection system (consisting of PES, I/P converters and K2 pilots) provides a backup means of closing valve ‘V’.
