Franklin Fueling Systems NANOVAPOR NV-SS ST-1000, Инструкция по установке и эксплуатации, Страница: 10 / 60

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Eliminating ignition sources
As previously mentioned, one ignition source is a spark. Sparks can occur for various reasons.
Spark production from Static Electric Discharge is common which is dangerous around flammable
vapors. Due to rapid movement of air molecules, an electro-static charge can build up on a
surface exposed to moving air. A spark will occur when an area of charge sufficiently builds,
and a conductive surface is brought in contact with the area of charge. The spark occurs as the
electrical field tries to balance itself. Correctly operating the NV-ST-1000 TankSafe™ Delivery Unit
in accordance to procedures will help avoid this hazard.
In order to prevent electro-static buildup on the NV-ST-1000 TankSafe™ Delivery Unit unit or
it’s ducting, the unit must be earthed (grounded) to the tank being degassed anytime it is in
operation and the tank earthing (grounding) must also be verified. Additionally, the ducting used
to connect the unit to the tank must be one that is electrically conductive such that the total
resistance of the system to earth (ground) is less than 10 Ohms.
The operator-supplied air compressor used to power the unit is also an ignition source.
Therefore, it should be positioned outside of the hazardous work area as defined by the user’s
operational procedures.
The following measures help remove ignition sources associated with the NV-ST-1000 TankSafe™
Delivery Unit:
• Be sure that the unit is properly earthed (grounded) at all times.
• Use conductive ducting to connect the unit to the tank you are working on.
• Always position the air compressor you are using outside of the hazardous area.
Inerting or degassing
Even when precautions are taken to remove ignition sources from the hazardous area, accidents
can still happen. Fuel vapors in the tank headspace can create a potentially explosive mixture
with air until their concentration is lowered below the LEL. This poses a serious safety threat to
workers, equipment and retail site property when performing tank inspections or maintenance.
Consequently, additional measures must be taken to reduce risk and remove another side of the
explosion triangle from the hazardous area (see Figure 2).
All fuel must be drained from the tank following the operator’s standard procedures as the first
measure. As much of the “dead stock” level is removed as well so minimal residual fuel remains
in the tank. You have two options on the second measure – either the oxygen or the remaining
fuel vapors must be removed from the tank headspace in order to further reduce the risk of
explosion.