Maintenance
Instructions on the handling of used SF
6
gas
and decomposition products
T51--251EN/01
4/4
03--1999
E ALSTOM
Recapitulation of important instructions
Reminder
Pure, non--contaminated SF
6
gas is non--poisonous. Electrical discharges
and fault--switching arcs will give rise to different grades of poisonous decom-
position products. In small amounts gaseous decomposition products pro-
duce -- within seconds and before any poisonous effects can take place --
warning symptoms, such as an unpleasant piercing odor, nasal, mouth and
eye irritations, which enable working personnel to withdraw to safety. Solid
decomposition products (powdery residues from switching) can cause skin
irritations. SF
6
is about five times heavier than air, and in the absence of turbu-
lence, results in the gas collecting just above ground level and causing suf-
focation through a deficiency of oxygen.
Important
instructions
The table below recapitulates the important instructions to follow
at the time
of handling of used SF
6
gas and decomposition products :
No. Instruction
1 As soon as an unpleasant, piercing odor from decomposition
products becomes perceptible leave the substation room with-
out delay. enter the room only after thorough ventilation or when
wearing suitable oxygen breathing masks (with filtering or fresh
air device).
2 After disturbances, enter the substation room only after having
thoroughly aired the room or when wearing independent of ambi-
ent--air operating oxygen breathing masks, or alternatively, after
verifying by measurement that the ambient air contains at least
17% volume of oxygen, especially if, one has to reckon with the
concentration of SF
6
in hazardous amounts.
3 Enter rooms located below, and connected with the substation--
rooms after thorough ventilation only, or when wearing oxygen
breathing masks which operate independent of the ambient--air,
or alternatively, after having verified by measurement that the
ambient air contains at least 17% volume of oxygen.
4 Ensure that the room ventilation operates satisfactorily, whilst
maintenance work is being performed on SF
6
switchgear (dis-
charging and filling of gas, opening and cleaning of equipment).
5 When working on opened SF
6
switchgear protect skin against
contact with gas and avoid swallowing or inhaling of gas. Ensure
body, clothing and work--bench cleanliness. Wear special work--
overalls and after completion of work discard latter.
6 W ash skin which comes in contact with powder deposits with
plenty of water. Before work--breaks and after work wash face,
neck, arms and hands thoroughly with soap and plenty of water .
7 Do not stir--up powder deposits resulting from arc--switching.
Remove sticky powder with dry rags. Use suitable vacuum
cleaner with paper--filter to remove loose powder. Discard used
items and filter--bags in such a manner that powder deposit does
not spread. Before discarding neutralize used items.
8 Avoid eating, drinking and storing eatables in rooms with opened
SF
6
switchgear which contains powder deposits.
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