Powder filling Ex q
Powder filling Ex q is a technique where equipment is placed in an enclosure, and the enclosure is filled completely with powder in a such way that if an arc, spark or hot surface occur in the enclosure, it will not ignite the outer explosive atmosphere.
Equipment is placed in an enclosure which is filled completely with powder in a such way that if an arc, spark or hot surface occur in the enclosure, it will not ignite the outer explosive atmosphere.
Testing to standards
The design requirements for using powder to prevent explosions (from gases entering electrical equipment and enclosures) are specified in International Standard IEC 60079-5 or Australian/New Zealand standard AS/NZS 60079.5. This Standard is always applied together with IEC (or AS/NZS) 60079-0 – Explosive atmospheres equipment – general requirements.
The powder filling "q" explosion-protection technique is useful in applications that combine two or more types of protection to form an assembly that is used in Zone 1 hazardous areas.
There are limits to the power that may be contained within a powder-filled enclosure.
The standard sets the maximum limits as:
supply current of 16 A
supply voltage of 1000 V
power consumption of 1,000 W.
Voltages within the "q" enclosure may exceed the supply voltage, but there are limits to the energy that may be stored.
Special filling arrangements are required so the dry filling medium fits closely together around all components within the enclosure to ensure there are no significant voids.
There are minimum requirements regarding distance to earthed metal from any live components through the filling medium.
Types of tests
Here are some tests that may be applicable depending on the construction and material of equipment:
degree of Ingress Protection IP test
creepage distances measurement
dielectric strength test of the filling material.
Getting the test results
The results of our testing are presented in a test report that is endorsed by our local Australian laboratory accreditation body, NATA (National Association of Testing Authorities, Australia).
When product sample testing, design assessment (Ex test report) and quality assessment (quality assessment report) are successfully completed, an Ex Certificate of Conformity (IECEx or ANZEx) is issued by TestSafe.
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