Safe distance between flammable materials and oil depots

There seems to be no fixed standard for this safety distance; the information below is provided for the original poster’s reference! In my opinion, woven bags should be kept inside the room as much as possible: it helps ensure the fire safety of oil tanks ； Contributes to the aesthetic appeal of the factory area ； It helps prevent aging of woven bags. 1. The concept of fire separation distance: Fire separation distance generally refers to the horizontal distance maintained between two buildings or structures. No buildings may be constructed on these two structures, nor may any other combustible or flammable materials be piled there; no other devices or facilities storing combustible materials are allowed either. 2. Reasons for establishing fire separation distances in oil depots Setting fire separation distances between the buildings in an oil depot is an important measure to ensure its safety. Oil depots store large quantities of flammable and combustible liquids, and during the processes of receiving and storing these liquids, a significant amount of oil vapor is released. Areas such as tank farms, loading/unloading zones, and fuel dispensing areas often emit oil vapors. Meanwhile, production and living areas within the depot, such as boiler rooms, power distribution rooms, and repair shops, contain open flames. If oil vapors come into contact with these flames, combustion and explosion accidents can occur. To prevent such accidents, it is essential to maintain certain fire separation distances between the storage areas, operation areas, and areas with open flames. This helps to isolate the oil vapors from sources of fire, thereby avoiding or reducing the likelihood of fires. Even if a fire breaks out in the oil depot, the distance between the buildings prevents the fire from spreading to adjacent structures, thereby reducing the losses caused by the fire. When a fire breaks out in a oil depot, firefighting forces need to be sent to the site to extinguish it. To allow these forces to carry out their tasks, it is necessary to provide enough space for them to operate. Different fire separation distances are established to meet the various requirements of firefighting and to create the conditions necessary for putting out the fire. Therefore, fire separation distances are established in oil depots as a means to avoid or reduce the likelihood of fires ； The second is the need to minimize the losses caused by fires ； Third is the need to create conditions for firefighting. 3. Determination of the fire separation distance for oil depots: The size of the fire separation distance for oil depots is primarily determined based on the factor of radiant heat. When the structures within an oil depot catch fire, the intense radiant heat has a significant impact on the surrounding buildings. If not controlled and extinguished in a timely manner, the fire will spread rapidly to adjacent buildings, turning a small fire into a large one that can lead to disasters and cause significant losses. If a large fire separation distance is maintained, it will of course be safer, but this will result in a larger land area required and higher investment costs; thus, it not only consumes more land resources but is also uneconomical. Therefore, the determination of fire separation distances for oil depots must be considered comprehensively, ensuring both safety and cost efficiency. The comprehensive considerations for determining the fire protection spacing in oil depots also include the fire resistance rating of buildings and structures, their intended use, the degree of fire hazard associated with the products manufactured or stored there, as well as their characteristics; whether fire isolation measures are in place; and whether firefighters can arrive promptly to extinguish the fire. 4. Factors determining the fire separation distance for oil tanks: With the development of the petrochemical industry and technological progress, there are an increasing number of types of oils, and oil tank capacities are also growing larger. As a result, in the event of an accident involving these tanks, the resulting losses become greater and greater. To resolve the conflict between the fire safety of oil tanks and the space they occupy, it is necessary to reasonably determine the fire separation distances for these tanks by taking into account key factors such as oil and gas dispersion, flame radiation heat, properties of the oil, type of tank, firefighting equipment and procedures, as well as the likelihood of the tank catching fire. (1) The impact of oil and gas diffusion on determining the fire protection spacing for oil tanks: Due to the evaporation of oil, the gas space inside the oil tank is filled with oil vapor, which then diffuses outward through the tank’s breather valves and sampling ports and is released into the atmosphere. The evaporation rate of oil products is quite high; for example, in the southern regions of China, a ground-based steel oil tank with a capacity of 10,000 m3 can experience a daily evaporation rate of 0.5 to 1 ton of gasoline when storing it during the summer. Therefore, its danger cannot be underestimated. When oil is pumped into the tank, the gas inside the tank is also released into the atmosphere through the breather valve or vent holes. The greater the oil inflow, the more oil vapor is discharged. The oil and gas released into the atmosphere spread with the wind; within a certain area around the oil tank area, the concentration reaches the lower explosive limit, forming an explosive gas mixture that can explode and catch fire when exposed to an open flame. For a gasoline tank with an oil inflow rate of 300 t/h, at an wind speed of 0.5 m/s, an exhaust hole diameter of 0.6 m, and an explosion lower limit of 1%, the gasoline vapor can spread over a distance of 6.47 m. Therefore, it is very necessary to establish an appropriate fire separation distance between oil tanks. (2) The influence of flame radiation heat on determining the fire separation distance for oil tanks: After a fire breaks out in an oil tank, the radiation heat generated by the burning oil has a significant impact on nearby buildings and structures. Due to the effect of radiant heat, fires often break out in adjacent oil tanks or buildings. The radiant heat from a tank fire is related to the burning oil and the distance between them. Light oils have a high radiation intensity, while heavy oils have a relatively lower radiation intensity. The greater the distance between oil tanks, the less radiant heat they receive. Therefore, to prevent the spread of fire in the oil tank area, a certain fire separation distance must be maintained between the oil tanks within it. (3) The influence of oil properties on determining the fire protection distance for oil tanks: Light oils are volatile and have a low flash point, resulting in a higher fire risk. Heavy oil products are not volatile, have a low auto-ignition point, and thus present a relatively lower fire hazard. However, if heavy oil products can still emit large amounts of oil vapor when heated to a certain temperature, they are treated as light oil products. For oils that are prone to boiling over and splashing during combustion, the fire separation distances between their storage tanks are larger, and the tanks holding such oils that easily boil over are placed in separate tank groups from those holding oils that do not boil over easily. Flammable fuels have higher vapor emissions, while some heavy oils require heating; their storage conditions vary, so they are stored separately and separated by fire dikes. (4) The impact of tank type on determining the fire separation distance for oil tanks: When above-ground and semi-underground oil tanks rupture, the oil will leak out. A fire broke out in an underground oil tank; the flames were close to the ground, and the thermal radiation from them posed a significant threat to firefighters. At a fire scene, when the intensity of radiant heat absorbed by the human body exceeds 21 MJ/h·m2, protection from water guns is necessary; otherwise, blisters will form within 20 minutes. When precast reinforced concrete oil tanks or brick-built above-ground oil tanks explode, their tank walls collapse, resulting in the leakage of oil. When a dome tank explodes, its roof collapses. In the case of a fire in a floating roof tank, only the seal ring burns. Depending on the type of oil tank, the consequences of a fire and the methods for extinguishing it vary. Therefore, different types of oil tanks have corresponding fire separation distances. (5) The impact of fire-fighting equipment and operations on determining the fire separation distance for oil tanks. The degree of advancement of fire-fighting equipment directly affects the ability to control fires and extinguish them promptly. Therefore, a certain area must be reserved for fire-fighting activities, and large distances need to be maintained. In oil tank areas equipped with proper fixed fire extinguishing and cooling systems, in the event of a fire in the oil tanks, it is possible to detect the fire promptly and extinguish it, thereby controlling the spread of the fire ； On the other hand, there are fewer people near the oil tanks, and the working area for the staff is also smaller; therefore, the distance between the oil tanks can be reduced. Firefighting operations also have certain requirements regarding the site. If mobile cooling and fire extinguishing equipment is used, the spacing between oil tanks should meet the requirements for providing a working area for firefighters to enter the tank area in order to extinguish the fire. Here, first, it is necessary to consider the spraying angle of the mobile water gun ； Secondly, it is necessary to consider the threat posed by radiant heat from a fire in an oil tank to firefighters using handheld water guns. If the damage to the fixed foam pipelines of the oil tank is taken into account, then a location is needed to attach foam nozzles to the burning oil tank. For the steel oil tanks commonly used in oil depots, with capacities ranging from 1000 to 50,000 cubic meters, a spacing of 0.6D (where D is the diameter of the steel tank) is generally sufficient to meet the site requirements for fire fighting operations. In this regard, the spacing between oil tanks abroad is much smaller than the spacing specified in our country.

Could you be more specific? Exactly how many meters?

In my personal opinion, it is advisable to keep a distance of about 30 meters outside the reservoir’s perimeter wall! ! ! For reference only! ! !

It is precisely because there are no standards that I would like to hear everyone’s opinions.

This post was last edited by Guohun on 2009-9-4 at 14:43. For details, refer to the Design Code for Oil Depots GB50074-2002, Section 4, which deals with the safety distance between oil depots and their surrounding areas. Or refer to the Building Fire Protection Design Code and the Petrochemical Fire Protection Design Code.