arpadveress What can be identified as a possible ignition source in a possible hazardous environment?
EN 1127-1:2012 lists 13 ignition sources in a row like mechanical, open fire, electrical, temperature, etc.
The real matter here: what is that/are these on site? Ok.s are electrical equipments, mechanical installations, etc – most of them you can get certified from the market. But what else?:
- forklift’s forks,
- tools,
- safety helmet,
- failure in the windows,
- etc…
How do you protect your Ex environment against any possible ignition sources?
EN 1117-1:2012 is for whom?!
First of all it is for Ex industry owners in general. You may invite anyone come to site and do inspection, but at the end of the day the responsibility is in his/her hands to show up proof of evidence of Ex safe functioning.
Pls note: EN 1127-1 has been fully adopted into ISO 80079-36.
But let me go back to the listed items:
- forklift’s forks – you may use a special condom to pull over and use it – your only task: to check it prior to use – education is mandatory
- tools – no certification requested but manufacturer’s manual shall be followed and considered – education is mandatory
- safety helmet – PPE (there shall be a separate post about) but even if being no ignition source is confirmed by manufacturer, it is the user’s responsibility to follow and document it accordingly – education is mandatory
- failure in the windows – is it that much important? Think of Robinson Crusoe – he was able to ignite fire with his glasses on the no-name island – why not in a possible hazardous environment…
The fight against possible ignition sources like above shall be a daily task of one or more (in my understanding: all) being responsible for site Ex safety… BUT therefore an understanding of Ex is mandatory input…
Minimum competencies are fully described in IEC 60079-14/-17 and -19. InHouse Competency System shall focus on those competencies highlighted there.
Source of ignition Cause (examples)
Hot surfaces Heating devices, mechanical processes due to friction and chipping, heat losses (friction coupling and braking)
Electric arcs Mechanically-generated sparks (e.g. due to friction, impact or machining processes), electrical sparks, electrical switch arcs
Flames and hot gases Flames and also their hot reaction products such as hot gases and glowing material particles can ignite an explosive atmosphere.
Mechanically-generated sparks Friction, impact or machining processes such as grinding, tools such as wrenches, pliers or tools such as a ladder; work on rusty components with aluminum tool (thermite reaction)
Electrical Systems Opening and closing of electrical circuits, equalizing currents, electromagnetic fields, conductive dust
Note: protective low voltage is not a measure to protect against explosion, since an ignition is also possible with less than 50 V!
Cathode corrosion protection Reverse current to the current source, induction, short or earth faults
Static electricity Discharge of static electricity
Lightening strike
Electromagnetic fields Frequency ranges from 9 x 103 Hz to 3 x 1011 Hz. These include, e.g. high-frequency systems such as radio systems or high-frequency generators.
Electromagnetic radiation Frequency ranges from 3 x 1011 Hz to 3 x 1015 Hz and wavelengths of 1000 μm to 0.1 μm. This includes optical radiation such as sunlight, lasers, lightning strike sources, electric arcs, etc.
Ionizing radiation Ignition due to energy absorption, which is caused e.g. by short-wave UV rays, x-rays or radioactive materials.
Ultrasonic Ignition due to energy absorption, which is caused e.g. by short-wave UV rays, x-rays or radioactive materials.
Adiabatic compression, shock waves, and streaming gases Due to the high temperatures that occur due to shock waves and in case of adiabatic compressions, an atmosphere subject to explosion can ignite.
Chemical reaction Due to chemical reactions that cause heat development (exothermic reactions), materials heat up and can cause an explosion.