Development of a method for predicting the ignition of explosive atmospheres by mechanical friction and impacts (MECHEX)

Proust, Christophe; Hawksworth, Stuart; Rogers, R. C.; Beyer, Michael; Lakic, D.; Raveau, David; Hervé, Philippe; Pina, Vincent; Petitfrere, Claire; Lefebvre, Xavier

doi:10.1016/j.jlp.2007.04.027

Cited by 28 publications

(19 citation statements)

References 4 publications

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“…There was no evidence of any ignition to be undoubtedly attributable to a flying spark in the present experiments [5]. There was even no evidence of any fragment to burn in the surrounding atmosphere even in the extreme situation of aluminum rubbing intensively against hard steel.…”

Section: Sparkscontrasting

confidence: 48%

“…These temperatures have been estimated for a number of atmospheres (hydrogen-air, methane-air, propane-air, ethylene-air, diethyl-ether-air, acetone-air,…) and compared to critical temperatures determined previously [9] for hot surface ignition in explosive atmospheres (Tpcrit).It has been realized that both sets of values correlate extremely well demonstrating that "frictional" ignition is a "hot surface" ignition mechanism. It has been however noted that the critical hot surface temperature does not seem to correlate so well with the standard autoignition temperature nor better with the minimum ignition energy [5], indicating that this might be a new type of ignition criterion. …”

Section: Ignition Around the Heated Surfacementioning

confidence: 98%

“…The sliding velocity can be adjusted between 0.05 and 15.7 m/s and the normal load between 0.2 and 1000 N. Temperatures have been measured by optical methods and thermocouples. During the tests, the normal load, friction coefficient and speed were controlled [5,8,10]. In some tests, flying fragments (sparks material) have been collected in order to evaluate the size of them and the wear rate.…”

Section: Experimental Equipmentmentioning

confidence: 99%

“…In some tests, flying fragments (sparks material) have been collected in order to evaluate the size of them and the wear rate. For steel rubbing against steel at a few m/s, the typical particle size seems of the order of a few hundred of mm and the wear rate, extremely dependent on the experimental conditions, is better scaled in mm 3 /s [5].…”

Section: Experimental Equipmentmentioning

confidence: 99%

“…So the ignition should occur most probably at at the hot contact zone before any possibility of ignition throughout volume could arise [5].…”

Section: Volumetric Ignitionmentioning

confidence: 99%

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Analysis of Ignition Risk on Mechanical Equipment in ATEX

Petitfrere

Proust

2007

2007 4th European Conference on Electrical and Instrumentation Applications in the Petroleum &Amp; Chemical Industry

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-Until the implementation of the ATEX directive 94/9/CE, the certification of equipment intended to explosive atmospheres was only dedicated to electrical equipment. Since the 1st July 2003, the non-electrical sources of inflammation are also to be looked at before putting an ATEX equipment on the market (pumps, couplers, reducing gears, …).Among these sources, mechanical friction and impacts are a main cause of ignition of explosive atmosphere. The risk analysis of the equipment consists in considering the failures, which can lead to ignition. If the failure involves a friction between two parts or an impact, we shall estimate if this friction or impact dissipates a sufficient amount of energy to ignite the surrounding explosive atmosphere.As part of the European program MECHEX, we have studied the process of degradation of the mechanical energy into heat during friction and impacts and we have examined the mechanisms of ignition at the contact zone. An extensive experimental program is presented and some "simple" modelling is proposed on purpose of practical applications. For frictional situations, a critical rubbing power is calculated without any limitations as for a potential lower boundary concerning the rubbing velocity. For "impacts", the relevant parameter for ignition is not the kinetic energy of the projectile but its velocity and the nature of the materials.

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Section: Sparkscontrasting

confidence: 48%

Section: Ignition Around the Heated Surfacementioning

confidence: 98%

Section: Experimental Equipmentmentioning

confidence: 99%

Section: Experimental Equipmentmentioning

confidence: 99%

“…So the ignition should occur most probably at at the hot contact zone before any possibility of ignition throughout volume could arise [5].…”

Section: Volumetric Ignitionmentioning

confidence: 99%