The size of the bladder accumulator for Plan 53B is determined mainly by three factors:
 
1. Volume of barrier fluid to be stored

In compliance with API 682 standards, the system shall operate continuously for a minimum of 28 days without refilling barrier fluid.

Extra capacity is reserved to accommodate thermal expansion and contraction of barrier fluid caused by temperature changes.

2. On-site operating pressure range

The accumulator relies on the compression and expansion of nitrogen gas inside the bladder to stabilize barrier fluid pressure,

keeping the barrier fluid pressure consistently higher than the pump seal chamber pressure. The allowable pressure fluctuation range of the system directly defines the required accumulator size.

3. On-site operating temperature

Temperature variations alter nitrogen pressure. For high-temperature conditions or applications with large temperature swings,

a larger safety margin for the accumulator is required to prevent overpressure or insufficient pressure.
 
In addition, the accumulator bladder cannot be fully collapsed. Extra protective allowance is considered during sizing.

The pressure vessel shell meets relevant pressure vessel codes, ensuring complete separation between gas and liquid and preventing nitrogen from dissolving into the barrier fluid.

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