Description
Depressurised buffer fluid circulation in outboard seal of a dual seal configuration through a seal support system. Circulation is maintained by using pumping ring in running condition and by thermosyphon effect in stand still condition.
Features
- No process contamination.
- No direct process leakage to atmosphere.
- No need to maintain pressure system as in Plan 53A.
Use
- For media where product dilution is not allowed but leakage to atmosphere in diluted form may be allowed.
- Preferred for clean, non-polymerizing media with vapour pressure higher than buffer fluid pressure
(Is also used for lower vapour pressure media).
Caution
- Keep the sealant vessel vent continuously open, which is necessary to maintain buffer fluid pressure close to atmospheric pressure and vent the vapors to flare.
- Should not be used in dirty or polymerizing products.
- A restriction orifice is necessary in vent line to maintain back pressure in pot and facilitate quick release of vapors to flare.
- Pressure switch setting should be done above minimum flare back pressure in order to avoid false alarms.
- Never run the system with level in the sealant vessel being at low level as marked on the level gauge.
- Check for temperature difference in inlet and outlet lines to ensure that circulation is on.
- Vent the system properly before start up.