1. SF6 Gas Decomposed! Special handling practices
Billy J Lao General Manager DILO Direct Odessa FL

2. Items to be discussed Sulfur Dioxide SO2 Description Safety
SO2 – Contributing factors
How to identify the presence of SO2
Handling SF6 containing by-products
SO2, mitigation and neutralization

3. Sulfur Dioxide (SO2) Chemical Formula SO2
Consists of 1 Sulfur and 2 Oxygen atoms (Dioxide)
Can be found in our atmosphere in low concentrations
It is a toxic gas with a pungent, irritating smell (rotten eggs)
Safety
SO2
Major polutant and in case of exposure a potential health issue
Inhalation can contribute to increased respiratory symptoms and disease, difficulty in breathing, and premature death
NOTE: Those with asthma are likely to be more sensitive to SO2 and may have stronger/ heightened negative reactions
SO2 can be found as a powder in an area where it has formed, but may also be found in vapor space in GIE or in cylinders.
SO2 is a reactive substance that can have a negative impact on materials such as metals (found in GIE) as well as other materials in GIE and gas handling equipment as it is highly corrosive and acidic.

4. Contaminants – SF6 Decomp Byproducts
Sulfur Dioxide (SO2)
Contaminants – SF6 Decomp Byproducts
Excerpt: Nov 29, 2006 – EPA Conference –Presentation on SF6 by-product handling – ICF International

5. Sulfur Dioxide (SO2) contributing factors
Arc Byproducts
Formed by the bonding of split atoms from SF6, trace gases (i.e. moisture vapor) and metal oxides (erosion byproducts) after an event causing the SF6 molecules to separate when exposed to heat > 385 F (normal operation or a fault)
Highly corrosive
Can shorten maintenance intervals
Can cause equipment failure in high enough concentrations
Very acidic in nature
Can pose a severe health risk
Created from electric discharges
Partial discharges (normal conditions & abnormal conditions)
Switching arcs (normal operation)
Failure arcs (i.e. GIE dielectric failure)
etc.

6. Sulfur Dioxide (SO2) contributing factors
Primary Contaminants

7. Sulfur Dioxide (SO2) contributing factors
Decomposition products of SF6
At very high temperatures, or in the presence of an electric arc which can reach 15,000C (27000F), SF6 can be slowly decomposed. Decomposition by-products include lower fluorides of sulfur, which are hydrolyzable, yielding SO2 and HF.
Major decomposition products formed in the presence of an electrical arc or at > 385 F are directly related to the temperature, time of circuit arcing, contaminants (such as moisture) and the equipment components.
Generally, S2F2 and SF4 (sulfur tetrafluoride) are present but rapidly react with water to further decompose into SOF2 (thionyl fluoride).

8. Sulfur Dioxide (SO2) detection
Perform SF6 Quality Check to ensure OEM requirements before energizing
Ensure you have the correct equipment, adapters & test/analyzer to meet the needs of your testing
Gas Quality Check
Purity / Vol %, SO2, H2O (moisture)

9. Sulfur Dioxide (SO2) detection (245kV DT)

10. Sulfur Dioxide (SO2) detection 550kV DT

11. Sulfur Dioxide (SO2) detection 69kV DT

12. Handling SF6 gas containing SO2
Adequate sized recovery system: guarantees the most amount of gas can be recovered in a reasonable amount of time
lbs. SF6
lbs. SF6 
30-60 lbs. SF6
0-30 lbs. SF6

13. Handling SF6 gas containing SO2
Use Pre-Filter systems to remove SO2 from SF6 gas
Dedicated pre-filter system with hose & fittings
Set-up with activated aluminum oxide filter cores for removal of moisture and SF6 by-products in the gas vapor
Spare filter cores on hand for exchange as required

14. SO2 Mitigation and Neutralization
Personal Protective Gear (per CIGRE Guide 23.10)
New SF6 Gas
Non-arced Sf6 Gas
Normally arced Sf6 Gas
Heavily arced SF6 Gas
IEC 376
Insulated Testing
Routine Maintenance
Maintenance & repair after normal operation.
Switchgear development tests
Decommissioning of switchgear
Switchgear after heavy testing or failure
Internal arc failure
optional
Work in well-ventilated areas. Clean work place and PPE are very important aspects for safe handling of SF6 Gas during switchgear maintenance. Since SF6 Gas is much heavier than air, warning signs should be placed in buildings where SF6 Gas may be stored, used or contained (i.e. GIS facilities). Oxygen content monitors should be installed to assure sufficient oxygen is present for breathing.

15. SO2 Mitigation and Neutralization
Caution tape or rope
Hepa filter vacuum
Neutralizing agent
Denatured alcohol
10 to 1 ration of baking soda and water
Lime soda water
Wipes & Rags
pH Testing Strips
Waste material bags/drum
By-Product handling Procedure
Acid vapor filters (white label)
Respirator program
Tyvek suite
Rubber gloves / Booties
All other applicable PPE
Wash station/wash kit
Soap & water
Industrial First Aid kit
Kapiteleinführung

16. SO2 Mitigation and Neutralization
After removing access covers and/or GIE disassembly
Dry vac all solids (powder)
Avoid work down wind/against the wind.
Use neutralization agent to remove remaining SO2/by-product
Ensure all contaminated materials are placed in collection bags and eventually in disposal drum.
Account for composition of neutralized materials
Required for Haz-mat disposal & emitter accountability
Test for presence of acidity using pH strips
Things to consider
Vapors may still be present in the gas compartment.
After exposure to moisture (i.e. exposing to atmosphere), the metal fluoride substance (solids) that has formed as a result of SF6 break-down will absorb moisture. This may allow the powder to become sticky/gum like. This substance is acidic and is very difficult to remove. Thus exposure time to atmosphere prior to clean up should be minimized.

17. SO2 Mitigation and Neutralization
GIE - HV Circuit Breaker
gas compartment

18. SO2 Mitigation and Neutralization
Performing repairs of a GIE should be performed by/with the guidance and technical support of the O.E.M.
If respiratory system is compromised, call 911 and advise emergency services that the victim has been exposed/inhaled acid gas
In the event of exposure use soap and water to wash off skin and eye wash to remove any contamination from eyes.
Ensure all work is performed in a well ventilated area.
Ensure all mitigation and neutralization waste is properly disposed of by following the local and industrial requirements
Performing evacuation and filling by following O.E.M. requirements
i.e. for every 8-hrs of exposure of gas compartment to atmosphere, 1 hour of evacuation at blank off pressure.
Use N2 to increase moisture wicking process
Repeat evacuation process
If respiratory system is compromised, call 911 and advise emergency services that the victim has been exposed/inhaled acid gas
In the event of exposure use soap and water to wash off skin and eye wash to remove any contamination from eyes.
Ensure all work is performed in a well ventilated area.
Ensure all mitigation and neutralization waste is properly disposed of by following the local and industrial requirements

19. Billy Lao – General Manager Odessa FL & Casa Grande AZ Questions?
DILO Direct
Billy Lao – General Manager
Odessa FL & Casa Grande AZ
Questions?