6 Commissioning/Start-up/Shutdown
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Vitaprime
6.1.7.3 Types of seal supply systems
Which of the two types of seal supply systems is used depends on the mechanical
seal:
6.1.7.3.1 Quench liquid
6.1.7.3.1.1 Applications
A quench liquid is used in the following cases:
▪
Where a single mechanical seal without supportive measures would not work at
all or unsatisfactorily.
▪
Where a double mechanical seal design with pressurised barrier fluid is not
required.
6.1.7.3.1.2 Quench liquid requirements
The quench liquid should preferably form a solution with the fluid handled and be
environmentally compatible.
Typical quench liquids
▪
Water with a conductivity of 100 - 800 µS/cm
▪
Water/glycol mixture
▪
Glycerine
5)
The quench liquid should be supplied to the mechanical seals unpressurised (at
atmospheric pressure), if possible. Positive pressures of up to 0.5 bar are acceptable.
The one-way quench supply should be adjusted to a constant flow ≥ 0.4 l/min.
Periodically check the quench liquid for contamination (replace quench liquid and
clean quench system if necessary).
6.1.7.3.1.3 Applications
For seal types T and H, operating mode BQ
6.1.7.3.2 Barrier fluid system
6.1.7.3.2.1 Applications
Barrier fluid systems serve to:
▪
Dissipate friction heat
▪
Prevent the fluid handled from entering the sealing gap
6.1.7.3.2.2 Barrier fluid requirements
The barrier fluid should preferably form a solution with the fluid handled and be
environmentally compatible. The barrier fluid should be monitored: Any ingress of
the fluid handled can be identified at an early stage by the barrier fluid becoming
turbid.
The temperature differences between the barrier fluid and the fluid handled must
not exceed 5 °C. A general minimum temperature of 0 °C applies to the barrier fluid.
The barrier fluid system must be set to a pressure which exceeds the pressure inside
the pump by approximately 0.5 to 1 bar.
General rule: The maximum permissible pressure inside the barrier fluid system
equals 10 bar. Actual maximum permissible pressure depending on the material
combination and shaft diameter:
5)
Make sure the circulation line diameter is ≥ ¼".
