Effect of sprinklers on the patient's survival probability in hospital room fires

The effectiveness of sprinklers in protecting a patient in a hospital room fire was investigated by performing 26 sprinklered and four free-burn experiments in real hospital rooms equipped with water-based automatic suppression system. Three different fire loads were used: UL 1626 corner test fire and two different textile fires. The measurements included temperatures, pipe pressure, and concentrations of about 20 different gas compounds. Based on the measurement results, we calculated the Fractional Effective Dose (FED) and Fractional Irritant Concentration (FIC) –values, and estimated the likelihood of incapacitation as a function of time. The results showed that sprinklers maintained temperatures at low level and reduced toxicity, mainly through fire development control. In UL1626 and large textile fires, sprinklers decreased the patient's incapacitation probability from 0.9 or above to the level of 0.4. In small textile fires, the difference between the incapacitation probabilities of sprinklered fires and free-burns was less than the measurement uncertainty. FED results were sensitive to the calculation method due to the different treatment of NOx –gases.Peer reviewe

Sprinklerien tehokkuus potilashuoneiden palosuojauksessa

Sprinkler systems are known to be effective at limiting fires in their early stages. However, as they often do not fully extinguish the fire, smouldering combustion will continue to produce different hazardous gases like CO. These gases can cause danger to humans. Prolonged exposure to low concentrations or high concentrations in a short period of time may cause incapacitation. In this thesis the conditions in post sprinkler activation environment were investigated. The data used in this thesis was collected from full-scale experiments performed in autumn 2018 in patient rooms of an old health center. Altogether 30 experiments were performed, in which used hospital textiles and foam mattress were burned, also adaptations of UL 1626 standard experiment were conducted. From these experiments temperatures and different gas concentrations were measured. The effects of different asphyxiant and irritating gases were assessed with Fractional Effective Dose (FED) and Fractional Irritating Concentration (FIC) models. The assessment was performed with both, so called “Purser-model” and according to ISO 13571 standard. Also, contributions of different gases towards FED and FIC were calculated. By using statistical methods, the probability, that a patient staying in the room would become incapacitated, was estimated. From the experiments it was concluded that sprinklers are effective at limiting temperatures at fires. With sprinklers the patient level temperature remained under 50 ℃ in all experiments. Without sprinklers temperature exceeded 150 ℃ at patient level in larger textile fires and UL 1626 experiments. In free small textile fires temperatures remained within tolerable limit. Incapacitation, caused by hazardous gases, can occur in 5- 8 minutes in sprinklered large fires. Without sprinklers the incapacitation can occur in 2-3 minutes. In both sprinklered and free small textile fires the likelihood of incapacitation is small.Sprinklerit ovat tunnetusti tehokkaita rajoittamaan tulipalon kasvua ja leviämistä. Ne kuitenkin harvoin sammuttavat palon täysin. Kytevä palo voi jatkaa haitallisten aineiden, kuten hiilimonoksidin (CO) tuottoa pitkään sprinklerijärjestelmän aktivoitumisen jälkeen. Työssä tutkittiin täydenmittakaavan kokeiden avulla henkilön toimintakyvynmenetyksen todennäköisyyttä huoneessa, jossa sprinklerijärjestelmä on aktivoitunut. 30 kokeen sarja suoritetiin syksyllä 2018 vanhan terveyskeskuksen potilashuoneissa. Kokeissa poltettiin suuria ja pieniä tekstiilipaloja, sekä suuria UL 1626 standardikokeen mukaisia vaahtomuovipatjapaloja. Kokeista suoritettiin myös sprinklaamattomat verrokkikokeet. Palotilassa mahdollisesti oleskelevan henkilön toimintakyvyn arvioinnissa otettiin huomioon sekä kaasun lämpötila että myrkylliset kaasut. Ärsyttävien ja tukahduttavien kaasujen vaikutusta toimintakykyyn arvioitiin Fractional Effective Dose (FED) ja Fractional Irritating Concentration (FIC) menetelmillä. Menetelmistä käytettiin niin kutsuttua Purserin - menetelmää, sekä standardin ISO 13571 mukaista menetelmää. Kokeissa havaittiin, että sprinklerit ovat tehokkaita jäähdyttämään ja rajoittamaan tulipaloa. Lämpötilat pysyivät turvallisina kaikissa sprinklatuissa kokeissa. Sprinklerit kuitenkin sammuttivat palon vain noin 30 %:ssa kokeista, näissäkin kyteminen jatkui pitkään. Ilman sprinklereitä lämpötilat nousivat vaarallisiksi kokeissa, joissa palokuormat olivat suuria. Kaasupitoisuuksien osalta voidaan todeta, että toimintakyvyn menetys on mahdollista 5-7 minuutissa suurissa paloissa. Verrokkina suoritetuissa sprinklerittömissä suurissa paloissa havaittiin, että toimintakyvynmenetys voi tapahtua jopa alle 2-3 minuutissa. Sprinklatuissa ja sprinklaamattomissa pienissä tekstiilipaloissa toimintakyvynmenetys ei ole todennäköist