Extinguishment of cable fires at packaged transformer substations

Introduction. According to the statistical data, electrical fires account for the majority of all fire accidents. Hence, better fireproofing of fuel and energy facilities is a relevant issue. The article addresses electrical fire extinguishment using high-expansion foam. An extinguishment time analysis methodology, applicable to fire extinguishment using high-expansion foam, has been developed to validate these solutions. The purpose of this article is to calculate the dependence between the fire extinguishment time and the foam consumption rate. The research objectives are to 1) identify the principal values to be used in the calculations and the list of input data; 2) to identify the dependence between the extinguishment time and the foam consumption rate using packaged transformer substation 2BKTP (1,000 kVA) as an example. Calculation methodology. The calculation methodology is based on the material balance equation between the amount of foam, applied for firefighting purposes, and the amount of foam, destroyed as a result of its contact with the heated wire surface, which is the main fire load inside burning electrical facilities. Research results. The co-authors have calculated the fire suppression time using packaged transformer substation 2BKTP (1,000 kVA) as an example. Dependencies between fire extinguishment time, specific foam consumption rate, and foam application rate are identified. Conclusions. The co-authors have identified the main values, needed to simulate a fire extinguishing model. They have also shown optimal foam consumption and application rates and offered their assessment of the applicability of high-expansion foam to electrical fires.

Responses of Pigs to Stunning with Nitrogen Filled High-Expansion Foam

Nitrogen gas (N2) delivered in high expansion foam in a closed container could be a feasible method for humanely stunning pigs. This study aimed to evaluate potential aversion in pigs to the N2 foam method and its effect on stun quality. Furthermore, the study aimed to assess potential aversion to the foam itself. Sixty pigs (27.8 ± 4.4 kg) were divided into three treatments and were exposed to either N2-filled foam, air-filled foam, or no foam air. The N2 foam was effective at purging the air from the container and quickly created stable anoxic conditions. The pigs did not show any strong aversive behaviours when exposed to foam. However, they seemed to avoid putting their heads and snouts into the foam when foam levels became high. Escape attempts through the lid also increased when the foam started covering their heads. The mean time to loss of posture was 57.9 s. Based on the results, stunning with the N2 foam technique could be a viable alternative to high concentration CO2 stunning and potentially lead to improved animal welfare at slaughter.

EFFECT OF OPERATING PARAMETERS UPON PERFORMANCE OF FUNCTIONAL SPECIMENS OF HIGH EXPANSION FOAM GENERATORS

The issues related to application of high expansion foam as flooding fire extinguishing agent as well as necessity of the development of high expansion foam generators in Ukraine are considered. Patent search concerning appropriate devices for generation of high expansion foam from foam solutions was conducted and it showed specific features of the components when generating high expansion foam. The results of the research of operating parameters of prototypes of high expansion foam generators of fan and ejection types are presented. For high expansion foam generators of fan type dependence of foam expansion, foam solution flow rate and amount of spent foam solution on the performance of the spray nozzle at different pressures and ratio of fan performance to the spray nozzle performance was established; the ratio of the cross-sectional area of the fan to the total area of the perforated holes in the foaming grid was studied, too. For high-expansion foam generators of the ejection type dependence of foam expansion, foam solution flow rate and amount of spent foam solution on the capacity of the spray nozzle unit at different pressures, foam solution flow rate to the total area of the holes in the foaming grid, and ratio of the cross-sectional area of the generator to the total area of the perforated holes of the foaming grid were studied. Functional models of the mentioned types of generators (both ejection (aspiration) one and generator equipped with fan (air blowing unit)) were developed, created and tested for the purpose of derivation of appropriate relations between their conditions of use and performance. At the same time, high expansion foam generators of fan type by their weight and size parameters are intended for use in the divisions of the Operative and Rescue Service of Civil Protection of the State Emergency Service of Ukraine as portable firefighting units. Such firefighting units are intended to be installed first of all on any state-of-the-art municipal fire engines equipped with autonomous AC generators. High expansion foam generators of ejection type are intended for use as firefighting units in foam firefighting systems of various facilities with fire hazard.

Istraživanje požarne sigurnosti spremnika nafte i derivata u Republici Hrvatskoj

SAŽETAK: Odjeljak Gašenje požara i hlađenje nadzemnih spremnika hrvatskog Pravilnika o zapaljivim tekućinama (PZT) u neskladu je s europskim i američkim normama i preporukama koje se odnose na ovo područje zaštite od požara. PZT objavljen je još 1999. godine, no ni u trenutku objavljivanja nije bio u skladu s tada u svijetu postojećim preporukama i dobrom tehničkom praksom. U međuvremenu su korištenjem zahtjeva iz PZT-a izrađeni mnogi projekti i izgrađeni sustavi vatrozaštite spremnika nafte i derivata kako u RH, tako i u susjednim zemljama, mahom nastalima raspadom SFRJ. Vrijednost takvih sustava i njihova očekivana učinkovitost u slučaju buknuća požara je upitna. U radu su prikazane bitne razlike između PZT-a te europske i hrvatske norme Stabilni protupožarni sustavi - Sustavi s pjenom - 2. dio: Projektiranje, izvedba i održavanje, kao i neke razlike u odnosu na odgovarajuću američku normu Standard for Low-, Medium-, and High-Expansion Foam. NFPA 11 je od 1922. doživjela više od 20 izdanja i od tada se uobičajeno koristila kao osnova za izradu odgovarajućih normi u cijelome svijetu. Glede zahtjeva za gašenje i hlađenje nadzemnih spremnika, konzultirani su relevantni i u svijetu priznati standardi API, kao i relevantne europske publikacije i preporuke. Odjeljak Gašenje požara i hlađenje nadzemnih spremnika hrvatskog PZT-a je pogrešno koncipiran, sadrži zahtjeve za sustave pjene koji su nedovoljno precizni ili čak pogrešni, te prenaglašava zahtjeve za hlađenjem vodom. Predlaže se njegovo povlačenje i zamjena s normama HRN EN 13565-2:2009 i HRS CEN/TS 14816:2018 Stabilni protupožarni sustavi – Sustavi raspršene vode – Projektiranje, ugradnja i održavanje. Ujedno se predlaže revizija projekata svih izvedenih sustava za gašenje požara pjenom i hlađenje nadzemnih spremnika zapaljivih tekućina napravljenih prema PZT-u, jer izvedeno stanje u mnogim slučajevima ne jamči dovoljnu razinu zaštite u slučaju požara. Uz to bi bilo uputno provjeriti dimenzije sabirnih prostora, koji su uglavnom predviđeni samo za prihvat sadržaja spremnika, bez uzimanja u obzir volumena rashladne i oborinske vode kao i vatrogasne pjene.

Fire extinguishing in with polydisperse foam of high multiplicity

Risk of fire and smoke dangers are greater in high-rise rather than low-rise buildings. Use of high expansion foam delivered through elevator shafts can prevent or reduce smoke and fire damage and injury in high-rise buildings. Injection of foam with high multiplicity due to structural rigidity can accumulate between floors of buildings to prevent the spread of flame and smoke. Reaching an area of high-intensity flame, this foam is destroyed, resulting in the absorption of energy from the upward flow of products of combustion.