Encapsulation Ex m
Encapsulation protection uses the principle of exclusion of an explosive atmosphere from the equipment by enclosing the equipment, that are capable of causing sparking or heating, in a compound, in such a way to avoid ignition of explosive atmosphere.
Testing technique
Encapsulation protection uses the principle of exclusion of an explosive atmosphere from the equipment by enclosing the equipment, that are capable of causing sparking or heating, in a compound, in such a way to avoid ignition of explosive atmosphere.
The electrical equipment or Ex components are fully enclosed in compound. Compounds can be any thermosetting, thermoplastic, epoxy resin or elastomeric materials in their solid state.
Encapsulation involves specific requirements for the minimum thickness of the compound surrounding the electrical components and circuit, and its ability to withstand any heat given off by them or the surrounding atmosphere.
Electrical and mechanical strength and the avoidance of voids within the encapsulant is very important.
Use of a protective device
A protective device could be used to limit the maximum surface temperature when the encapsulated equipment is subjected to a single fault (mb) or two faults (ma). It should be either external or directly integrated into to the equipment.
The protective device shall be capable of interrupting the maximum fault current of the circuit in which it’s installed.
The rated voltage of the protective device must correspond to the working voltage of the circuit in which is installed.
Thermal protective devices shall be used to protect the compound from damage caused by local heating i.e. due to faulty component.
Properties of compounds are critical for an encapsulation type of protection. These minimum the properties shall be considered:
- temperature range of compound (continuous operating temperature – COT)
- dielectric strength in accordance with IEC 60243-1
- water absorption
- adhesion of compound to component and to enclosure if relevant
- the temperature index TI value or relative thermal index – RTI-mechanical impact
- comparative tracking index – CTI.
Assessment and testing to Standards
We can assess and test to the International standard IEC 60079-18 or Australian/New Zealand standard AS/NZS 60079.18 (explosive atmospheres) for equipment protection by encapsulation 'm' for both explosive gas and dust atmospheres. This is always applied together with the standard IEC (or AS/NZS) 60079-0 for explosive atmospheres, equipment - general requirements.
There are three equipment levels of protection:
- ‘ma’: Equipment level protection EPL Ma, Ga, Da
- ‘mb’: Equipment level protection EPL Mb, Gb, Db
- ’mc’: Equipment level protection EPL Gc, Dc.
Types of tests
Here are some of the tests that may be applicable depending on the construction and material of equipment:
- temperature-rise test
- thermal endurance to heat and cold
- resistance to chemical agents for Group I
- impact test
- drop test
- water absorption test
- dielectric strength test
- distance measurement.
Enquire about encapsulation Ex m test
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.
Help and support
Complete our online enquiry form.
Call: +61 (2) 4724 4900
Email: testsafe@safework.nsw.gov.au
Mail us at: PO Box 592, Richmond, NSW 2753 Australia.