IEEE 637-1985

1 Introduction
2 Scope
3 Definitions
4 References
5 Classification of service-aged oils and criteria
       for reuse
5.1 General classification of service-aged oils
5.2 Suggested limits for classes of service-aged oils
5.3 Economic factors
5.4 Sources of oil to be reclaimed
5.5 Precautions
5.5.1 Askarel
5.5.2 Silicone fluids
5.5.3 Other fluids
5.5.4 Suspended carbon
5.6 Criteria for resuse of reclaimed oil
5.6.1 Makeup or replacement oil for transformers and
       reactors which are out of warranty
5.6.2 Makeup or replacement oil for oil circuit
       breakers
6 Types of reconditioning and reclamation processes
6.1 Gases and water-vacuum dehydration
6.2 Water and solids
6.2.1 Blotter or filter press
6.2.2 Centrifuge
6.2.3 Coalescing filter
6.2.4 Precipitation or settling
6.3 Adsorption of soluble contaminants
6.3.1 Materials
6.3.2 Contact process
6.3.3 Percolation by gravity
6.3.4 Percolation by pressure
6.4 Types of pressure percolation
6.4.1 Bulk filters
6.4.2 Deep bed filtration
6.4.3 Throw-away and repackable cartridges
6.4.4 Percolation by thermo-siphon bypass
6.5 Activated carbon sodium silicate process
6.6 Reclamation by trisodium phosphate
6.7 Modern oil reclamation systems
6.7.1 Normal systems
6.7.2 On-site energized systems
6.8 Locations
6.8.1 Centralized reclamation site for pooled oil
6.8.2 Mobile reclamation of pooled oil
6.8.3 Reclamation of oil in transformers and associated
       devices using mobile equipment
6.9 Choice of methods
7 Oil tests and their significance
Figures
1 Adsorption by attapulgite-clay
2 Schematic diagram of gravity-percolation refining
       apparatus
3 Bulk clay filters
4 Three-clay tower system
5 Fuller's earth cartridge filters
6 Schematic diagram of trisodium phosphate/Fuller's
       earth refining apparatus
7 Typical flow diagram for modern, oil-reclamation
       system
Tables
1 Suggested limits for in-service oils group 1 by
       voltage class
2 Suggested limits for oil to be reconditioned or
       reclaimed
3 Suggested property requirements of reclaimed oil
       for transformers
4 Suggested test limits for reclaimed oil in
       transformers and reactors after filling, but
       before energizing
5 Suggested test limits for reclaimed oil in
       circuit breakers, reclosers, and load tap oil-
       purification practices
6 Oil-purification practices
7 ASTM test procedures
Appendix
       Bibliography

Covers mineral insulating oil commonly defined as transformer oil; definition and description of reclaiming procedures; the test methods used to evaluate the progress and end point of the reclamation process, and what criteria recommended for the use of reclaimed oils are considered suitable.