General information
Paint storage and paint mixing rooms are designed to feed paint to automated paint lines. Paint lines and paint preparation/mixing are usually unique in a assembly plant. Solvent based paints and thinners are received in totes or drums directly from the manufacturer and are stored in metal containers in the paint storage room. Quantities vary from a few liters to 1,420 l (around 375 gallons). Storage can be on floors, racks, on shelves or on flow-through racks. Storage heights are variable but usually do not exceed 3 m (10 ft.). They are then moved to a paint mix room, also called a paint kitchen, where they are put in mix tanks. The paint is continuously churned and pumped from the mix tanks through insulated stainless steel pipes to the paint spray booths. Pumps are pneumatic. The paint piping system consists of supply, return and recirculating pipes. Typically, the paint is continually recirculated to prevent solidification. In some cases, supply paint temperatures are controlled by hot water heat exchangers. The mix and storage rooms are either detached or cut off from the paint shop building.
Paint mixing room Paint storage
Claim experience
Facts:
Fire on Friday 09/03/2012 at 7:20 pm in a paint booth
Fire alarm triggered and reported to the employees (supervision) and to the guard house
Call of the fire brigade
Presence of personnel on site to confirm the alarm
Automatic shutdown of air, electricity, ventilation, paint and solvent distribution
30 seconds later, the CO2 extinguishing system is activated
Arrival on site of the firemen around 7:35 pm (15 minutes)
Control of the fire around 10:00 pm and departure of the firemen at 2:00 am on Saturday 10/03
Facts from the claim investigation:
Starting point of the fire: purge pot located in a cabin used to clean the spray nozzle of the paint application robot.
Fire linked to an electrostatic phenomenon providing sufficient energy to ignite solvent vapors.
Given the damage: impossible to test the continuity of the ground connection of all the equipment in the destroyed booth.
The ground connection was made by means of a metal braid connected to a crocodile clip (teeth), which was itself attached to the handle of the can used as an emptying pot.
Very small contact surface (two teeth) and draining can be covered with a paint paste due to the overflow of the purged residues.
Impossible to demonstrate the lack of grounding of the emptying pot of this cabin but very likely a hypothesis.
The two optical flame detectors located in the cabin functioned properly.
The CO2 extinguishing system functioned correctly as well as the energy cut-off and ventilation/ extraction slaves.
However, the CO2 did not allow sufficient impregnation to obtain the extinction of the slow combustion at the level of the paint traces
Facility was not equipped with shut-off valves.
Propagation to the whole cabin by rapid combustion when the CO2 is stopped
Consequences:
Destruction of the entire paint line and its contents.
Very important damage to buildings and installations.
The building was not totally destroyed, but large damages due to smoke, soot, and temperature rise.
Were saved by the intervention of the firemen:
Grinding room with liquids stock and preparation areas
Adjacent room which sheltered the moulds of the presses
No pollution of the river located near the plant
Consequences of the disaster on the operation of the sites:
Upstream flow to a main facility which manufactures the raw material.
Downstream flow to 4 other production locations of the group or external to the manufacturers
Financial loss:
Buildings o 3.5 M€
Equipment + cleaning o 8.5 M€
Commodities o 0.5 M€
Costs and losses o 1.8 M€
Damages
ELEN Risk Consulting recommendations
Although not exhaustive, the following basic prevention recommendations can significantly improve the resilience of the company that plans to install a painting line. Recommendations need to be seen from a pragmatic perspective to reduce the potential for significant property damage and associated business losses:
General issues:
ATEX regulations or equivalent respected
Only non-combustible material shall be used such as mineral wool insulated metal sandwich panels shall be used for construction
All electrical and pneumatic equipment installed in explosion hazard areas shall be explosion-proof and in accordance with local standards if stricter
All equipment (spray guns, venting ducts, piping, etc.) should be equipped with electrical bonding and grounding so that static electricity is eliminated.:
All energies (compressed air, electricity) interlocked with the operation of the sprinkler protection by means of a flow switch. The flow switch must be equipped with a testing device (pipe and valve downstream, linked to the sewer).
Mixing room/paint storage:
The mixing room should be ideally at least 60 min fire-resistive
Adequate retention/spill containment shall be installed. Minimum capacity ½ of total stored liquid volume.
Adequate bonding and grounding provided.
Adequate mechanical ventilation provided (minimum 0.3 m3/min/m²)
Sprinkler protection
Explosion-proof of electrical and pneumatic equipment
Booth:
Sprinkler protection
UV type flame detection installed in the flaming booth, with an interlock of the conveyor, so that it is stopped in case of fire
Main electrical cabinet:
Smoke detection and clean agent (Inergen, Nitrogen, etc – no FM 200) automatic extinguishing system installed inside the cabinet
Sprinkler protection design:
Design according to NFPA 13 latest edition
All equipment UL-listed or FM approved
Sprinklers fed by a dedicated control valve for large painting lines (above 500 m²: must be different from the one of the ceiling protections) or with a specific waterflow switch for small painting lines
Booths: either 12.2 or 16.3 mm/min over 186 m² minimum, spray sprinkler heads 68°C rated
Oven protected by sprinkler, minimum rating 40 °c above the maximum temperature, or 141 °c, whatever is greater
Entrance ducts: o Protection ton be discussed case by case especially depending on the position of the entrance duct. If located 5 m from exhaust air, it can be discussed not to install a sprinkler.
Exhaust ducts: o Filter boxes protected by automatic sprinklers upstream and downstream the filters, minimum density of 114 l/min per head
Basement, where recycling is located, should be sprinkler protected either 12.2 or 16.3 mm/min over 186 m² minimum, 68 °c rated spray heads
Mixing room: 25 mm/min over 186 m² or the entire area, whatever is greater. Foam depends on the volume of flammable liquids. Foam system designed for 15 minutes duration, K160 sprinkler heads; if not possible consider a deluge system designed for 25 mm/min over the entire area (no foam in this case).
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