Normally Hexane is not recommended as Buffer/ Barrier fluid.
It is low viscosity and low boiling point solvent.
Buffer fluid should be compatible with process fluid. If Hexane is used as buffer fluid , it automatically is compatible.
Probably this is the reason of selecting Hexane as buffer fluid.
For solid particles , both F/F and B/ B seal should not be used.
F/B ( Tandem seal is best.
Face combination of inboard seal should be hard face combination.
Spring should be out of product.
Stationary spring seal is always better than rotating seal.
Technically stationary and rotating Seal as...
For Condensate extraction pump only Plan 13 should be sufficient. No need of Plan 32.
In case there is chance of vapourisation due to pressure drop created by Throat bush, use Plan 14.
API does not allow gland packing.
in case of Mechanical Seal API Plan 13 will be right selection. In this case liquid does not impinge on to the seal and moves away from the seal faces, hence chances of seal face erosion will reduce.
The standard mention following in special notes
"API...
For liquids with solid, both Face to Face and Back to Back should not be considered.
My recommendation is Face to Back ( Tandem seal) with hard face combination.
There is no published guideline, but individuals take decision as per their experience.
STATIONARY VS ROTATING SEAL
Even though API...
API does not allow gland packing.
in case of Mechanical Seal API Plan 13 will be right selection. In this case liquid does not impinge on to the seal and moves away from the seal faces, hence chances of seal face erosion will reduce.
The standard mention following in special notes
"API...
