On the other hand Kst, along with P max (Maximum explosion overPressure) assesses the destructive potential of the dust cloud in case the ignition starts. It is the equivalent of the explosion class given to the highest value describing the pressure rise in a closed vessel which is determined under specific test conditions, and expressed in bar

plantas) o ATEX 153 (aplicable a las compañías operativas) exigen a polvo, y de conformidad con ATEX 153. (Directiva KSt-Value: Aprox. 30 bar x m/s para

St1 : 0 < Kst < 200 Explosion Isolation Valves The installation of an explosion isolation device on all suction side ducts that transport material with a Kst value above zero is an NFPA requirement. Installing a Explosion Isolation Valve will protect workers and facilities from the damaging effect of a baghouse or filter explosion. Kst-value for classification into dust explosion classes St 1, St 2 and St 3. Examples of explosion parameters: Explosion pressure and explosion severity The dust explosion classes are the basis for designing constructive pro-tection measures in addition to the maximum explosion pressure pmax.

Examples of explosion parameters: Explosion pressure and explosion severity The dust explosion classes are the basis for designing constructive pro-tection measures in addition to the maximum explosion pressure pmax. Dust explosion classifications The St class is based on the K St value as follows: St 0 - K St value = 0. St 1 - K St value less than/or equal to 200 bar-m/sec and greater than 0. St 2 - K St value between 201 and 300 bar-m/sec. St 3 - K St value greater than 300 bar-m/sec an ATEX zoned environment or for suctioning a flammable substance are protected in different ways to ensure that the dust filter itself does not become a source of ignition. Explosion protection Kst value (m.bar/s) Dust class (Dust) > 0 to 200 1 > 200 to 300 2 > 300 > 3 The Dustmasters that are also suitable for extraction however, and any material with a Kst value greater than zero is considered to be at risk of an explosion. Other than silicon or sand, every kind of dust is potentially combustible to some degree.

ATEX Important choices at filter unit dimensioning: To be able to dimension and place a unit the information of Kst, Pmax, dust type determination and relief conditions is important. Kst-value is an expression of explosion aggressivity (bar m/sec): ST-class Kst ST1 Kst-value less than 200 bar m/sec. ST2 Kst-value between 200 and 300 bar m/sec.

Table 3: K St Values for Organic and Metal Dusts Dust type K st Value Barley Grain 240 Rice Starch 190 Pectin 162 Kst = (dP/dt)max x V 1/3. From this we can go on to work out for you what size and opening pressure of explosion relieve vents you need to prevent your vessel from rupturing** – to keep the explosion pressure below the Pred, as we say. In fact, Kst is an internationally agreed ‘normalized’ rate of pressure rise. the esta atex programme and fire protection concept - for a safe workplace There is a risk of fire and explosion in all industrial installation s in which flammable and explosive dusts occur.

The maximum rate of pressure rise can be measured on the pressure vs time graph (see above) and then Kst calculated knowing the volume V of the test vessel : (dP/dt) max = Kst.V-0.33 [Laurent] Kst is expressed in bar.m/s. Depending on the value of Kst, powders can be classified in classes. St1 : 0 < Kst …

The system design incorporated explosion protection suitable for a dust with a KST value < 200bar. m.s-1. KSt maximum value of the pressure rise per unit time (dp/dt)max during the explosion of a specific explosive 3) See also ATEX Guide 10.3 and Annex ZA. Both DSEAR and ATEX recognise dusts as explosive risks.

From this we can go on to work out for you what size and opening pressure of explosion relieve vents you need to prevent your vessel from rupturing** – to keep the explosion pressure below the Pred, as we say. In fact, Kst is an internationally agreed ‘normalized’ rate of pressure rise. the esta atex programme and fire protection concept - for a safe workplace There is a risk of fire and explosion in all industrial installation s in which flammable and explosive dusts occur.
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Actually, a rapid rise of pressure makes it compulsory to adopt larger vents or to manufacture a vessel with a higher resistance to the rise of pressure. The fire generated by a product bearing a higher Kst will be longer and faster.
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Example BETHPULS Bag Filter for Dedusting plant for aluminium powder Dust characteristics Kind of dust Dust explosion class KSt- value Explosion overpressure pmax Lower explosible limit Protective measures Prevention of effective ignition sources Explosion pressure shock resistant up to11.0 bar Disengagement raw gas side Rapid action valve clean gas side Rapid protection valve Overspraypowder

. Before deciding what equipment will be suitable for your zone, your supplier will need the following information about the product you handle: Kst value. This is a Kst value and Pmax are explosive properties measured in the laboratory to quantify the severity of a dust explosion. The explosion indices test follows EN tivity of explosive dust clouds is characterized by the Kst value, defined as the rate of pres- It appears that the new ATEX directives have created a demand for.

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Dust Explosion Venting in Silos: a Comparison of Standards NFPA 68 and EN 14491. Alberto Tascón* a, Pedro J. Aguado. a. and Alvaro Ramírez. b. aDepartment of Agricultural Engineering, ESTI Agraria, Universidad de León, Av. Portugal 41, 24071 León, Spain.

The Kst value equates to the maximum rate of pressure rise in a 1 m3 vessel (in bar. compliance to major process safety regulations (SEVESO/ATEX/OSHA). How quickly a dust deflagration occurs determines its KST value.