NFPA 13: 2019, section 126.96.36.199 quotes " Where cushion tanks are used with automatic fire pumps, no check valve is required in the cushion tank connection". and no where in NFPA standards it is mandatory requirement to install cushion tanks.
My understanding regarding Air vessel / Cushion chamber / Surge protection devices in fire pump installation is that it is not mandatory in any case but it is acceptable to install these devices for the purpose of following purposes,
1. To prevent damage to fire protection systems by accommodating the expanded volume of system fluids that result from temperature changes. This keeps the system pressure below the pressure limitations of the components.
2. To absorb pump start-up and shut-down surges in fire protection sprinkler systems.
Am I right?