There are many methods to pressurize the barrier fluid for a dual pressurized mechanical seal. Each method, or piping plan, uses a different mechanism to apply the pressure to the barrier fluid and, as a result, each has its own set of advantages.
One of these methods is American Petroleum Institute (API) Plan 53C. Although not as widely installed as a traditional API Plan 53A system, it does differentiate itself from other methods. API Plan 53C has the ability to change the barrier pressure as the pressure inside the pump changes.
This pressure tracking ability makes this system ideally suited to highpressure pumps, or for pumps that tend to experience a wide range of operating pressures.
Image 1 (left). Simplified Plan 53C schematic. Image 2 (center). Typical piston accumulator. Image 3 (right). Piston face areas (Images courtesy of FSA)
A Plan 53C barrier system consists of two main elements: