RENZMANN units of ATEX category 1 for zone 0 inside
Explosion protection of RENZMANN solvent distillation units according to ATEX equipment directive 94/9/EC (ATEX 95)
External explosion protection
The outside of RENZMANN solvent distillation units meets the requirements of ATEX category 2; the units may therefore be operated in explosion hazard zone 1.
Internal explosion protection
When solvent in a container is heated to a temperature above its flash point, a potentially explosive solvent vapor/air mixture is generated above the liquid level. That is why the inside of containers filled with flammable liquids is classified as zone 0 according to the Technical Guidelines for flammable liquids (TRbF 20 ch. 8.2.1).
While the solvent vapors in the distillation boiler displace the atmospheric oxygen during boiling, an explosive solvent vapor-air atmosphere exists frequently and persistently above the liquid level during the following operating modes:
during and after filling while the heating is off,in the heating phase,during ventilation before and during residue discharge, andwhen solvent is filled into the unit to dissolve incrustations
This means that the criteria of zone 0, a permanent or frequent presence of a potentially explosive atmosphere, are definitely fulfilled. Therefore, the interior of the distillation boiler is classified as zone 0 in Code of Practice T001 of BG-Chemie "Small distillation units for solvents" (ch. 5.5) and must meet the requirements of category 1 devices according to ATEX.
D.W.RENZMANN solvent distillation units
meet the requirements of category 1 devices on the inside and may therefore be operated with zone 0 on the inside. are equipped with electrical and moving mechanical components on the inside that are type-examined according to ATEX.
Explosion protection of the vacuum unit
The vacuum unit extracts the explosive atmosphere above the liquid in the distillation boiler until a vacuum is established, and maintains the vacuum by sucking off air that leaks into the distillation unit from outside. The vacuum pump delivers air if the vacuum must be reduced due to foaming or to prevent cavitation caused by leak air at the suction side of the vacuum pump. This means that the vacuum pump constantly aspirates explosive atmosphere at vapor/air temperatures above the flash point, and the inside of the pump must therefore be classified as zone 0.
D.W.RENZMANN uses liquid jet vacuum pumps made of metal that are grounded and have no moving parts; hence there are no potential ignition sources. Consequently, these pumps may be operated with zone 0 on the inside.The centrifugal pump that primes the jet pump is always filled with solvent, i.e. there is no explosive atmosphere on the inside; this is monitored redundantly.
RENZMANN only uses liquid ring vacuum pumps (centrifugal) for solvents with a flash point > 50°C and if the distillate is cooled down below the flash point in the condenser of the distillation unit (this is monitored). Pumps of this type do not meet the requirements of category 1 for low flash points, unless very sophisticated monitoring equipment is used and certain process parameters are observed that are impossible to comply with in the daily running of a distillation unit.
Fulfillment of the "CRITERIA FOR THE SELECTION OF EQUIPMENT AND PROTECTIVE SYSTEMS" according to the ATEX workplace directive 1999/92/EC (ATEX 137)
D.W.RENZMANN uses a certified quality assurance system according to ATEX and consistently implements all relevant legal requirements.
The operator is required by ATEX 137 to use equipment of the correct category for the respective hazard zones, e.g. category 1 equipment for zone 0.
D.W.RENZMANN supplies category 1 distillation units with a type examination according to ATEX and thereby protects customers from any liability due to unsuitable or prohibited distillation units, irrespective of the solvent used.
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