Maximum accumulation for a single safety valve?

Maximum accumulation for a single safety valve?

• A. 5%
• B. 15%
• C. 10%
• D. 20%

Answer: (C)

Maximum accumulation is the allowable rise in system pressure above the valve’s set pressure that can occur while the relief device is relieving. For a single safety valve protecting a vessel, this allowance is 10% of the valve’s set pressure. In practice, that means the highest pressure the protected vessel should see during a design event is 1.10 times the set pressure, giving the valve and its discharge path a margin to respond without exceeding the vessel’s design limits. If more than one relief device is present, the system can accommodate a larger accumulation because the aggregate relief capacity shares the load (up to about 20% in some configurations). The other options (5%, 15%, 20%) don’t apply to a single valve in typical practice—the 10% limit is the standard for a lone relief device.

Maximum accumulation is the allowable rise in system pressure above the valve’s set pressure that can occur while the relief device is relieving. For a single safety valve protecting a vessel, this allowance is 10% of the valve’s set pressure. In practice, that means the highest pressure the protected vessel should see during a design event is 1.10 times the set pressure, giving the valve and its discharge path a margin to respond without exceeding the vessel’s design limits.

If more than one relief device is present, the system can accommodate a larger accumulation because the aggregate relief capacity shares the load (up to about 20% in some configurations). The other options (5%, 15%, 20%) don’t apply to a single valve in typical practice—the 10% limit is the standard for a lone relief device.