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Problem magnified
Published:  09 November, 2016
entrance to Ybarra, smoke

The devastating fire that destroyed one the most important production plants in southern Spain is thought to have been caused by the relatively rare magnifying glass effect, reports George Potter.

According to initial investigations of the fire of 16 July at the Ybarra production plant in the town of Dos Hermanas, 15km south of Seville, the fire began in an exterior area where wooden pallets, cardboard boxes, plastic bottles, weeds and other abandoned combustible materials had accumulated without control.

Spain’s extreme temperature in mid-July had contributed to the dry state of the wooden pallets that served as the fuel for the fire and to the rapid propagation of the fire throughout the plant.

It is thought that the sun’s rays, concentrated on the debris by empty plastic bottles, resulted in the intense fire that destroyed four large olive oil storage tanks as well as several production installations and storage areas for mayonnaise and other foodstuffs derived from vegetable oils.

The magnifying glass effect is a not an uncommon cause of fires, and during the five-year period of 2010-2015 the London Fire Brigade documented some 125 fires caused by this phenomenon.

Soon after the fire had taken hold, the regional emergency communications centre received around 40 simultaneous telephone calls from around the plant reporting heavy smoke coming from inside the premises.

The first responders from the Dos Hermanas fire station, comprising one pump and a crew of four, immediately requested additional support and another pump and crew were despatched from Dos Hermanas, as well pumps, crews and a hydraulic platform from the surrounding towns of Alcalá de Guadaíra and Utrera as well as Seville city. Within a few hours the intensity of the smoke generated by the burning olive oil had led to the evacuation of two nearby residential communities.

Photo: @Rafaruiz76

At the height of the incident there were ten vehicles and over 30 firefighters on the scene under the operational command of Andalucía’s regional emergency management. By the following day the fire was under control, even if numerous small, isolated fires were still burning. Several pumps and firefighters remained on scene for the following two days to ensure the total extinguishment of the fires, while residents of the evacuated communities returned to their homes.

Four large oil storage tanks as well as processing and storage buildings were destroyed, while the main offices and laboratories were spared.

One of the reasons for the devastating impact of the fire lies in the chemical properties of olive oil, which has a flash point around 220ºC and which when heated may generate smoke at a temperature of around 160ºC. Olive oils burn at very high temperatures making the control and extinguishment of these fires very difficult. Also, as with most other burning vegetable oils, they generate extremely dense, nearly black smoke, which can impede access to the interior of involved buildings while provoking serious health problems. In Ybarra’s case, several buildings involved in this fire were lost because firefighters simply could not enter due to the extreme heat and dense smoke generated.

While all vegetable oils including olive oil can be considered as combustible liquids, they are in reality Class F fuels. This classification is normally applied to the cooking oils and greases found in kitchens in relatively small amounts. In this fire there were several hundred thousands litres of burning oil, a situation more akin to a petroleum storage facility.

The most common extinguishing agents used for Class F fires are water mist, wet agents and dry powders. These are fine against a couple of dozen litres of kitchen oils but in Ybarra’s case these extinguishing agents would not have been practical.

In this particular incident the wetting/foam agent Bio For N was used at a 1% application rate, and this did work.

There were no serious injuries or fatalities, although several employees and neighbours suffered from the effects of the dense smoke.

Fortunately for the company and its employees the disaster was not as devastating as it could have been. In October Ybarra announced yearly revenues of 200 million euros, only 14 million down from 2015. This was in large part achieved through a series of agreements with local firms that agreed to temporarily produce products on the company’s behalf.

A modern 30 million-euro, 30,000m2 factory is planned for completion in December 2017 to re-employ the 175 people that worked in the old plant.

Industry vulnerabilities

While the ratio of one firefighter per 1,000 population is generally considered to be the ‘ideal’, the average ratio in Spain is one for every 2,300 inhabitants.

In this specific region the Seville municipal fire brigade’s approximately 400 officers and firefighters protect a population of more than 696,700, while often responding outside the city's limits, as in the Ybarra fire.

The municipality of Dos Hermanas, with a population of more than 130,000 people and a multitude of industrial hazards, has a brigade of 70 officers and firefighters.

The two responding brigades from Alcalá de Guadaíra and Utrera, also equally below ideal staffing, were only able to respond with one vehicle and crew each. While doing so they left their respective stations completely unmanned.

Although the nearby Seville international airport and the joint Spanish and USAF airbase at Morón de la Frontera are both equipped with aviation crash tenders with foam application capabilities, neither were summoned to the Ybarra incident.

The incident has highlighted the vulnerability of Spanish industry to fire, given the sparse resources allocated to municipal emergency response and the lack of co-operation between private and municipal brigades.