Assessment ignitability

Other test methods can also be used to assess ignitability, together with other properties. Some important ones are the cone calorimeter (ASTM E 1354,71 Figure 21.7, which has the assessment of heat and smoke release as its primary purpose) the OSU calorimeter (ASTM E 906,38 Figure 21.8, which also... 

Vacuum pumps of category 2 which pump from zone 1 have to be subjected by the manufacturer to an internal control of production according to annex Vlll of the directive. In addition, the manufacturer has to deposit a technical documentation for the vacuum pump at a Notified Body, including a risk assessment, ignition hazard assessment and notes for the implemented measures to maintain the explosion protection. 

Flammability. Since almost all ethers bum in air, an assessment of their potential ha2ards depends on flash points and ignition temperatures. The flash point of a Hquid is the lowest temperature at which vapors are given off in sufficient quantities for the vapor—air mixture above the surface of the... 

Intrinsic Safety. Static electrical concepts such as minimum ignition energy do not directly apply when assessing the safety of electrical circuits such as radios, flashlights and instmmentation. Intrinsically safe electrical equipment is usually available which has been subjected to fault analysis and testing. The equipment must be certified for the flammable atmosphere in which it will be used (NFPA 497). Refer to texts on Intrinsic Safety such as [63]. 

It is recommended that flammability always be assessed first, since it is inherently safer to avoid flammable atmospheres than to avoid sources of ignition such as static electricity. If a flammable atmosphere cannot be avoided at all times, the system should be designed to minimize both the probability and consequences of ignition. In this chapter it is assumed that static electricity is the only source of ignition however, in practical situations all sources of ignition such as those described in [ 157] should be evaluated. 

In view of the above adverse effects a safety factor should be applied where flammability is assessed using flash point. For pure liquids in containers the vapor should be considered potentially flammable if the liquid temperature is upward of at least 5°C below the reported flash point. For mixtures whose composition is less certain, such as petroleum mixtures, the safety factor should be about 15°C relative to the flash point [55]. Where combinations of adverse effects are identified the safety factors should be increased accordingly. A simple but very conservative approach is to assume that all liquids having a flash point <141°F may produce a flammable atmosphere under some ambient conditions, even where no mist or froth production is involved. A more practical approach is to assume that liquids handled in air at least 5-15°C below their closed cup flash points will not present ignition risks unless... 

The major objective of the experimental program was to obtain data that could be used to assess the accuracy of existing models for vapor cloud dispersion. The combustion experiments were designed to complement this objective by providing answers to the question, What would happen if such a cloud ignited ... 

Figure 1 shows part of a solvent phase polypropylene plant. The plant consists of three process lines, denoted A, B, and C. During a risk assessment review, a scenario was identified that involved a release of reactor contents from a location near the west end of the A line. Estimates are needed of the blast overpressures that would occur if the resulting cloud of vapor, mist, and power ignites. 

In addition to assessing a fire s flame cliaracteristies to detennine tlie cause and effect of a fire, knowledge of tlie fire accident type will provide insight into its ignition source and possible fire protection and prevention methods. Electrical, chemical, and metal fires can occur in a solid, liquid, or gaseous pliase. Section 7.3 presents a detmled discussion of tliese fires and tlieir ignition sources. 

Fajardo, C.M. and V. Sick, Flow field assessment in a fired spray-guided spark-ignition direct-injection engine based on UV particle image velocimetry with sub crank angle resolution. Proceedings of the Combustion Institute, 31(2) 3023-3031, 2007. 

GS21 Assessment of the radio frequency ignition hazard to process plants where flammable... 

The first major hazard in process plant is fire, which is usually regarded as having a disaster potential lower than both explosion and toxic release2. However, fire is still a major hazard and can under the worst conditions approach explosion in its disaster potential. Fire requires a combustible material (gas or vapor, liquid, solid, solid in the form of a dust dispersed in a gas), an oxidant (usually oxygen in air) and usually, but not always, a source of ignition. Consider now the important factors in assessing fire as a hazard. 

For a dust ignition to occur, the suspended solids concentration must lie between lower and upper limits which vary from material to material and are influenced by subtle factors such as particle shape and size distribution. From the standpoint of assessing safety hazards in commercial and industrial operations, the lower explosive limit is the more important one. The rationale of this statement is that, if the possibility of exceeding the lower limit in a powder-handling operation can not be completely ruled out, then a hazard must be recognized and appropriate measures taken. Over the... 

Fire safety in a particular scenario is improved by decreasing the corresponding level of fire risk or of fire hazard. Technical studies will, more commonly, address fire hazard assessment. Fire hazard is the result of a combination of several fire properties, including ignitability, flammability, flame spread, amount of heat released, rate of heat release, smoke obscuration and smoke toxicity. 

Toxic potency of smoke data can be used as one of the inputs in fire hazard assessment. In particular, they can be combined with average mass loss rates and times to ignition to obtain a quick estimate of toxic fire hazard. 

Furthermore, it has been shown that the time period until ignition occurs, in the Cone calorimeter, is proportional to the inverse of the flame spread rate [16]. The Cone calorimeter can also be used to provide the mass loss rate information required for the simplified classification into categories of toxic hazard [1] quick toxic hazard assessment. Thus, the NBS Cone calorimeter is a very useful tool to overcome some of the disadvantages associated with measuring a single property at a time. 

For the assessment of resistance to heat exposure and generation of hazardous environments by FRC materials, the following processes need to be examined 1) ignition, 2) fire propagation, 3) generation... 

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