Safety cabinet
A safety cabinet is used to safely store flammable chemicals or pressurized gas bottles . It is intended to prevent the substances stored in the cabinet from promoting the spread of the fire or leading to an explosion in the event of a fire. The areas of application and users are diverse: industry, laboratories, crafts, universities, hospitals, public organizations that work with hazardous substances, safety engineers, safety officers, etc.
construction
The construction and testing of safety cabinets are regulated in the European standards EN 14470-1 (cabinets for storing flammable liquids) and EN 14470-2 (cabinets for storing and emptying pressurized gas cylinders).
Safety cabinets usually consist of the components inner body (wood or metal), fire protection insulation, supply and exhaust air valves with fuses, forced closing mechanisms for the doors in the event of fire (not for gas bottle cabinets), fire protection seals on the doors and optionally an earth connection.
In safety cabinets for flammable materials there are usually storage floors or full pull-outs on which the chemicals are stored. To prevent dangerous leaks , safety cabinets are equipped with floor trays.
Safety cabinets for pressurized gas cylinders are intended to hold pressurized gas cylinders. To extract the gases, feedthroughs are drilled into the cabinets at predetermined points, through which metallic pipelines are then laid. These pipe penetrations are to be sealed for fire protection. Many pressurized gas cylinder cabinets have "ramps" that can be inserted into the door or folded out so that the fire protection seals are not damaged when the cabinet is filled.
Models in various widths, heights and fire resistance classes and with different door and locking systems are available in stores:
- Widths (in cm): 60, 90, 120, 140
- Heights: tall cabinets or base cabinets available in different heights
- Fire resistance classes: F15, F30, F60, F90 or G15, G30, G60, G90 Protection against fire (in minutes)
- Door and locking systems: Folding and wing doors are also available with sensor-controlled and fully automated door opening / closing.
business
A connection of safety cabinets to a permanent exhaust air system is recommended. If a safety cabinet is not connected to a technical exhaust air system, a certain area in front of and around the cabinet is to be regarded as a Zone 2 hazardous area. If the safety cabinet is connected to a 24-hour technical exhaust air device, the potentially explosive area is limited to the inside of the cabinet. In order to prevent damage to the cabinet through corrosion, no acids or alkalis may be accommodated in this type of cabinet; there are special, corrosion-resistant cabinets (see: TRbF Appendix L: Storage facilities in workrooms (safety cabinets ) / points 4.1 and 4.2 as well as BGR 104 2.2 .8th).
If the connection to an exhaust air system is not possible on site, solvent and safety cabinets can be technically vented with a circulating air filter attachment. The devices filter the exhaust air from the cabinet through an activated carbon filter and return the cleaned air to the work area.
function
In the event of a fire, from an ambient temperature of approx. 50 ° C, the drawer pull-outs are pulled in and then the doors of the safety cabinet close. These processes are mostly controlled by bimetal triggers or fusible links. From an ambient temperature of approx. 160 ° C, the fire protection seals foam up and thus seal the joints on the doors. From approx. 70 ° C, the fire protection valves in the supply and exhaust air openings close. This means that the cabinet is hermetically sealed.
Safety cabinets with automatic door locking provide additional security. After a defined time interval, the cabinets close automatically, thus minimizing the risk of hazardous vapors escaping.
In the case of safety cabinets for pressurized gas cylinders, there is generally no automatic door closing, since the doors of these cabinets should always be closed during operation.
power
According to the fire resistance period, the safety cabinet prevents the stored goods from heating up. The temperature rise inside the cabinet is limited for the specified time. In the case of pressurized gas cylinder cabinets, the permissible temperature rise is 50 degrees ( K). When flammable liquids and solids, this value is 180 K. tested is in this fire wall chambers for testing with the EPC ( E inheits T emperaturzeit K curve).
exam
According to Sections 3 and 10 of the Ordinance on Industrial Safety and Health, as well as DIN EN 14470, safety cabinets must be checked regularly by a qualified person.
Test scope:
- Condition of the fire protection valves
- Condition of the fire protection insulation
- Condition of the fire protection seals
- Condition of the hinges
- Functionality of the door closing
- Function of the door lock
- Condition of the body (corrosion)
- Compliance with Ex areas
- Measurement of the exhaust air volume flow (with technical ventilation)
State of the art
Nowadays, when storing flammable liquids in a safety cabinet, a distinction is made between passive storage (closed containers) and active storage (open containers or decanting processes in the cabinet).
In the case of active safety cabinets, additional precautionary measures are provided according to the state of the art, e.g. B. mandatory ventilation or an electrically conductive powder coating of all metallic cabinet components.
The first safety cabinets (in the 1970s) had fire resistance times of just 20 minutes. By using calcining materials (instead of the rock wool insulation that was customary up to now), the fire resistance period could be extended to 90 minutes.
At the same time it became possible to drastically reduce the wall thickness (especially the door thickness). This made it possible for the first time to use folding doors instead of the usual revolving doors.
Individual evidence
- ^ Dittrich Egbert: Handbook for Sustainable Laboratories . Erich Schmidt Verlag, ISBN 978-3-503-13053-5 .
- ↑ Safety cabinets according to DIN EN 14470. In: GIT Labor-Fachzeitschrift. 11/2010, pp. 836–837 (PDF file, 201 kB)
- ↑ Udo Eickmann, Gabriele Halsen: Chemical hazards in the health service: Help for practice . ecomed Medicine, 2013, ISBN 978-3-609-10017-3 , p. 168 ( limited preview in Google Book search).
- ^ Reimund Neugebauer: Handbook of Resource-Oriented Production . Carl Hanser Verlag, 2013, ISBN 978-3-446-43623-7 , pp. 755 ( limited preview in Google Book search).
- ↑ BAuA: Federal Institute for Occupational Safety and Health: TRGS 526: Laboratories. Retrieved August 6, 2018 .
- ↑ BAuA: Federal Institute for Occupational Safety and Health: TRGS 510: Storage of hazardous substances in portable containers. Retrieved August 6, 2018 .
- ↑ BAuA: Federal Institute for Occupational Safety and Health: TRGS 509: Storage of liquid and solid hazardous substances in stationary containers as well as filling and emptying points for portable containers. Retrieved August 6, 2018 .
- ↑ Marc Platthaus: Laboratory Safety: How do active and passive positioning differ? Ed .: Vogel Communications Group GmbH & Co. KG. ( vogel.de [accessed on August 6, 2018]).
- ↑ BAuA: Federal Institute for Occupational Safety and Health: TRGS 727: Avoidance of ignition hazards due to electrostatic charges. Retrieved August 6, 2018 .