SAFEMATIC SWE-GLD Reliable Premium Double Seals Support Seal Water Control Monitoring System

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The most critical operating parameter for a dual seal water station is the differential pressure between the barrier fluid system and the pump seal chamber. John Crane recommends maintaining the barrier fluid pressure at 2.0 bar ± 0.5 bar above the seal chamber pressure at all pump operating conditions. For pumps operating with varying suction or discharge pressure (e.g., variable-speed or multi-stage pumps), the differential pressure must be maintained throughout the entire operating envelope.

Pressure Setting Procedure:

1. Measure or estimate the seal chamber pressure at the pump's normal operating point. For single-stage centrifugal pumps, seal chamber pressure is approximately 80–90% of the pump discharge pressure
2. Set the nitrogen pressure regulator to deliver barrier fluid pressure = seal chamber pressure + 2.0 bar
3. For Plan 53B bladder accumulators, pre-charge the bladder gas side to 60–70% of the required barrier fluid pressure; the system pressure will increase when barrier fluid is pumped into the accumulator fluid side
4. For Plan 53C with a piston accumulator, pre-charge the gas side to the same pressure as the required barrier fluid pressure; the circulation pump charges the system to the final operating pressure
5. Verify the relief valve set point is at least 1.1× the working pressure; the relief valve must pop before the seal's maximum pressure rating is exceeded

1. System Cleanliness Verification — Flush all piping and the reservoir with clean solvent; blow dry with nitrogen; ensure no debris, weld slag, or machining chips remain in the system
2. Barrier Fluid Fill — Fill the system with the specified barrier fluid (clean water, water-glycol, or synthetic oil per John Crane seal recommendation). Vent all air from the circulation loop via the highest vent point
3. Nitrogen Pressure Charge — Connect the nitrogen supply; set the pressure regulator to the calculated differential pressure; verify that the system holds pressure without decay for 15 minutes
4. Circulation Pump Start — Start the circulation pump (Plan 53C/54); verify flow through the sight glass; confirm barrier fluid temperature does not rise more than 5°C within the first 30 minutes of operation without cooling
5. Cooling Water Supply — Open cooling water supply to the heat exchanger; adjust flow until barrier fluid temperature stabilizes at 10–20°C above the cooling water inlet temperature
6. Pump Start & Differential Verification — Start the pump; monitor barrier fluid differential pressure; as the pump pressurizes the seal chamber, verify the differential stays within the 2.0 ± 0.5 bar target. Re-adjust the nitrogen regulator if the differential drifts
7. Alarm & Shut-Down Test — Test each alarm point: low-pressure, high-temperature, low-reservoir level. Confirm each triggers the specified alarm output and/or pump shut-down interlock

1. John Crane Dual Seal Model & Size — Seal type (Type 7, 8A-1, 8B-1, 89/99, 7160, 7180, 7198, etc.) and seal size in mm
2. API Piping Plan Required — Plan 53A, 53B, 53C, or 54; specify the preferred circulation method
3. Operating Conditions — Pump process pressure (min, normal, max), process temperature, and barrier fluid temperature target
4. Fluid Compatibility — Process fluid type (chemical name, concentration, pH, specific gravity) to select barrier fluid and wetted material compatibility
5. Reservoir Volume & Pressure Rating — 10 L / 20 L / 50 L standard; pressure rating 16 bar, 25 bar, or 40 bar
6. Power Supply — Voltage and frequency for circulation pump motor and instrumentation power
7. Special Requirements — ATEX/IECEx hazardous area rating, dual instrumentation for SIL-rated applications, or special material for aggressive barrier fluids

Payment: 70% T/T deposit, balance against copy of B/L.