External barrier liquid system pressurized by a piston accumulator supplying clean fluid to the inboard and outboard seal faces.
This plan works using an extraneous barrier fluid system that is pressurized by a piston accumulator supplying clean fluid to both inboard and onboard seal faces.
- Used with Arrangement 3 seals.
- Piston accumulator senses pressure from a reference source (normally the seal chamber) and maintains a higher barrier system pressure through differential areas in the piston.
- Barrier liquid pressure should always exceed the maximum seal chamber pressure by at least 20 psi [1.4 bar].
- Barrier liquid is circulated through the fluid circuit by means of an internal circulating device (pumping ring).
- Materials used in the piston accumulator must be compatible with the process fluid.
- Process fluid never leaks to the atmosphere unless system pressure is lost.
- Heat is removed using a heat exchanger.
- Barrier liquid must be compatible with the process liquid because it will leak into the product.
- Piston system provides continuous positive pressure differential between barrier fluid and seal faces
- Heat exchanger efficiently removes generated heat
- Process fluids containing solids may accumulate on metal surfaces
- Regular maintenance is required
- Barrier fluid and process fluids must be compatible due to the possibility of mixing