Venting impulse lines

With all due respect to the findings of the investigating team, the root cause appears to me to be a human factors situation. The new piping system looked simple but in fact this unique system was confusing. A check valve (valve no. 2) was installed on the vent header to prevent cross-contamination. A small block valve (valve no. 4) was installed on the vacuum relief impulse line to provide easy isolation. [5]... 

Proof test approaches Proof tests of wetted parts are not always the same. In some cases pressure injection to the main impulse line with isolation and vent valves may be possible, but in a case where there are chances of leakage of energy or fluids, such an approach may not be feasible. So, based on this some of the major approaches are ... 

Mr A. Forbes Gower raised a question on the BCD samples. It would not be feasible to use the Venturi tappings to withdraw a BCD sample as the flow through the Impulse line would introduce a pressure Imbalance and invalidate the instrument reading. It is essential to vent the Impulse lines to remove the gases and even occasional use for sampling would lead to... 

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