BERMAD FP- 42T / 42T-20 Fire Protection Pressure Reducing Valve - Resetting Procedure

This video shows and instructs in the procedure for resetting or calibrating a Bermad 42T or 42T-20 pressure reducing valve. The Bermad 42T and 42T-20 will reduce a high upstream pressure to a stable lower downstream pressure regardless of fluctuations in flow or upstream pressure, including static no-flow conditions.
This instruction includes the resetting of a Bermad relief valve typically installed downstream of any pressure reducing valve, as any change in the pressure reducing valve set pressure, will require a corresponding resetting of the relevant relief valve.
The Bermad model 42T-20 in addition to acting as a pressure reducing valve includes a built in non-return or check valve characteristic making it particularly suitable for the check valve requirement in fire sprinkler systems.
The 42T-20 also serves as a surge arresting valve at pump outlets, preventing damaging surge spikes at fire pump startup.

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Should the downstream side of the pressure relief valve be left open and not piped anywhere?