{"id":284853,"date":"2024-10-19T19:17:12","date_gmt":"2024-10-19T19:17:12","guid":{"rendered":"https:\/\/pdfstandards.shop\/product\/uncategorized\/bsi-pd-cen-tr-169882016\/"},"modified":"2024-10-25T16:07:22","modified_gmt":"2024-10-25T16:07:22","slug":"bsi-pd-cen-tr-169882016","status":"publish","type":"product","link":"https:\/\/pdfstandards.shop\/product\/publishers\/bsi\/bsi-pd-cen-tr-169882016\/","title":{"rendered":"BSI PD CEN\/TR 16988:2016"},"content":{"rendered":"

1.1 General<\/h3>\n

The measuring technique of the SBI (single burning item) test instrument is based on the observation that, in general, the heats of combustion per unit mass of oxygen consumed are approximately the same for most fuels commonly encountered in fires (Huggett [12]<\/span>). The mass flow, together with the oxygen concentration in the extraction system, suffices to continuously calculate the amount of heat released. Some corrections can be introduced if CO 2<\/sub>, CO and\/or H 2<\/sub>O are additionally measured.<\/p>\n

1.2 Calculation procedure<\/h3>\n

1.2.1 Introduction<\/h4>\n

The main calculation procedures for obtaining the HRR and its derived parameters are summarized here for convenience. The formulas will be used in the following clauses and especially in the clause on uncertainty.<\/p>\n

The calculations and procedures can be found in full detail in the SBI standard [1]<\/span>.<\/p>\n

1.2.2 Synchronization of data<\/h4>\n

The measured data are synchronized making use of the dips and peaks that occur in the data due to the switch from \u2018primary\u2019 to \u2018 main\u2019 burner around t<\/i> = 300 s, i.e. at the start of the thermal attack to the test specimen. Synchronization is necessary due to the delayed response of the oxygen and carbon dioxide analysers. The filters, long transport lines, the cooler, etc. in between the gas sample probe and the analyser unit, cause this shift in time.<\/p>\n

After synchronization, all data are shifted so that the \u2018main\u2019 burner ignites – by definition – at time t<\/i> = 300 s.<\/p>\n

1.2.3 Heat output<\/h4>\n
1.2.3.1 Average heat release rate of the specimen (HRR 30s<\/sub>)<\/h5>\n

A first step in the calculation of the HRR contribution of the specimen is the calculation of the global HRR. The global HRR is constituted of the HRR contribution of both the specimen and the burner and is defined as<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n

\u03c6<\/i> ( t<\/i>) The last two terms x<\/i> a_O2<\/sub> and [Formula removed.]<\/i> express the amount of moles of oxygen, per unit volume, that have chemically reacted into some combustion gases. Multiplication with the volume flow gives the<\/p>\n

amount of moles of oxygen that have reacted away. Finally this value is multiplied with the \u2018Huggett\u2019 factor. Huggett stated that regardless of the fuel burnt roughly a same amount of heat is released.<\/p>\n

The volume flow of the exhaust system, normalized at 298 K, V D298<\/sub>( t<\/i>) is given by<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n

The oxygen depletion factor \u03d5<\/i>( t<\/i>) is defined as<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n

The mole fraction of oxygen in ambient air, taking into account the moisture content, is given by<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n

Since we are interested in the HRR contribution of the specimen only, the HRR contribution of the burner should be subtracted. An estimate of the burner contribution HRR burner<\/sub>( t<\/i>) is taken as the HRR total<\/sub>( t<\/i>) during the base line period preceding the thermal attack to the specimen. A mass flow controller ensures an identical HRR through the burners before and after switching from primary to the main burner. The average HRR of the burner is calculated as the average HRR total<\/sub>( t<\/i>) during the base line period with the primary burner on (210 s \u2264  t<\/i> \u2264 270 s):<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n

HRR of the specimen<\/p>\n

In general, the HRR of the specimen is taken as the global HRR, HRR total<\/sub>( t<\/i>), minus the average HRR of the burner, HRR av_burner<\/sub>:<\/p>\n

For t<\/i> > 312 s:<\/p>\n

[Formula removed.]<\/i><\/p>\n

where:<\/p>\n

\n<\/div>\n

During the switch from the primary to the main burner at the start of the exposure period, the total heat output of the two burners is less than HRR av_burner<\/sub> (it takes some time for the gas to be directed from one burner to the other). Formula (24) gives negative values for HRR( t<\/i>) for at most 12 s (burner switch response time). Such negative values and the value for t<\/i> = 300 s are set to zero, as follows:<\/p>\n

For t<\/i> = 300 s:<\/p>\n

[Formula removed.]<\/i><\/p>\n

For 300 s <  t<\/i> \u2264 312 s:<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n

Calculation of HRR 30s<\/sub><\/p>\n

In view of the calculation of the FIGRA index, the HRR data are smoothened with a \u2018flat\u2019 30 s running average filter using 11 consecutive measurements:<\/p>\n

[Formula removed.]<\/i><\/p>\n

where<\/p>\n

\n<\/div>\n
1.2.3.2 Calculation of THR(t) and THR 600s<\/sub><\/h5>\n

The total heat release of the specimen THR( t<\/i>) and the total heat release of the specimen in the first 600 s of the exposure period (300 s \u2264  t<\/i> \u2264 900 s), THR 600s<\/sub>, are calculated as follows:<\/p>\n

[Formula removed.]<\/i><\/p>\n

[Formula removed.]<\/i><\/p>\n

whereby the factor 1 000 is introduced to convert the result from kJ into MJ and the factor 3 stands for the time interval in-between 2 consecutive measurements,<\/p>\n

and where<\/p>\n

\n<\/div>\n
1.2.3.3 Calculation of FIGRA 0.2MJ<\/sub> and FIGRA 0.4MJ<\/sub> (Fire growth rate indices)<\/h5>\n

The FIGRA is defined as the maximum of the ratio HRR av<\/sub>( t<\/i>)\/( t<\/i> \u2212 300), multiplied by 1 000. The ratio is calculated only for that part of the exposure period in which the threshold levels for HRR av<\/sub> and THR have been exceeded. If one or both threshold values are not exceeded during the exposure period, FIGRA is equal to zero. Two combinations of threshold values are used, resulting in FIGRA 0,2MJ<\/sub> and FIGRA 0,4MJ<\/sub>.<\/p>\n

    \n
  1. \n

    The average of HRR, HRR av<\/sub>, used to calculate the FIGRA is equal to HRR 30s<\/sub>, with the exception of the first 12 s of the exposure period. For data points in the first 12 s, the average is taken only over the widest possible symmetrical range of data points within the exposure period:<\/p>\n

    [Formula removed.]<\/i><\/p>\n

    [Formula removed.]<\/i><\/p>\n

    [Formula removed.]<\/i><\/p>\n

    [Formula removed.]<\/i><\/p>\n

    [Formula removed.]<\/i><\/p>\n

    [Formula removed.]<\/i><\/p>\n<\/li>\n

  2. \n

    Calculate FIGRA 0,2MJ<\/sub> for all t<\/i> where:<\/p>\n

    (HRR av<\/sub>( t<\/i>) > 3 kW) and (THR( t<\/i>) > 0,2 MJ) and (300 s <  t<\/i> \u2264 1 500 s);<\/p>\n

    and calculate FIGRA 0,4MJ<\/sub> for all t where:<\/p>\n

    (HRRav( t<\/i>) > 3 kW) and (THR( t<\/i>) > 0,4 MJ) and (300 s <  t<\/i> \u2264 1 500 s);<\/p>\n

    both using:<\/p>\n<\/li>\n<\/ol>\n

    [Formula removed.]<\/i><\/p>\n

    where:<\/p>\n

    \n<\/div>\n

    As a consequence, specimens with a HRR av<\/sub> not exceeding 3 kW during the total test have FIGRA values FIGRA 0,2MJ<\/sub> and FIGRA 0,4MJ<\/sub> equal to zero. Specimens with a THR not exceeding 0,2 MJ over the total test period have a FIGRA 0,2MJ<\/sub> equal to zero and specimen with a THR not exceeding 0,4 MJ over the total test period have a FIGRA 0,4MJ<\/sub> equal to zero.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Estimation of uncertainty in the single burning item test<\/b><\/p>\n\n\n\n\n
    Published By<\/td>\nPublication Date<\/td>\nNumber of Pages<\/td>\n<\/tr>\n
    BSI<\/b><\/a><\/td>\n2016<\/td>\n58<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":284856,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[279,2641],"product_tag":[],"class_list":{"0":"post-284853","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-17-200-01","7":"product_cat-bsi","9":"first","10":"instock","11":"sold-individually","12":"shipping-taxable","13":"purchasable","14":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/284853","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/284856"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=284853"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=284853"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=284853"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}