Fires zones

The fire zone drawings serve as an aid in determining which areas need special protection measures such as adequate fireproofing, firewater protection systems, drainage facilities, etc. 

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Locate batch operation outside of affected fire zone... 

If manual fire-fighting is also anticipated following agent discharge, visibility in the fire zone requires consideration. 

Visibility in the fire zone after extinguishant discharge, if manual fire-fighting is anticipated. 

Catch basins should be provided for each fire zone of the process area to collect the flow from the floor drains and trenches. All catch basins within the process area battery limits should be sealed for vapor control. Catch basin seals should be of types that are easily cleaned out. P-traps should not be used. Catch basins require a periodic check to verify that a liquid seal is in place and clean-out plugs are installed. 

For example, API 521 for fire case calculations basically allows you to ignore heights above a certain height when considering how much vessel surface to include in a fire zone calculation (see Section 2.3.2). Some companies go up to 8 m while others go up to 30 m for fire sizing and others simply have no height limit, considering that for a fire in a tank farm, for instance, it has been demonsttated that flames can reach over 100 m. 

The release of 131I and other fission products in reactor accidents has been considered in the previous chapter. In the Windscale accident, the temperature in the fire zone reached an estimated 1300°C and 8 tonne of uranium metal melted. Over 25% of the 1311 in the melted fuel escaped to atmosphere. In the Chernobyl accident, the fuel was U02, the temperature exceeded 2000°C, and about 25% of the total reactor inventory of 131I was released to atmosphere, as vapour or particulate aerosol. In the Three Mile Island accident, 131I remained almost completely in the reactor coolant. The activities of 131I released in reactor accidents, including that at Chernobyl, have totalled much less than the activities released from weapons tests (Table 2.3). 

If the effluent is stratified, the gas sample is obviously unrepresentative, but if it is uniformly distributed, then the gas flowing into the fire zone may be oxygen depleted and fire gases may be recycled through the fire zone. These latter effects will be greater with thicker specimens, which would be expected to generate more smoke, due to more complete consumption of oxygen and hence to under-ventilation. 

In all of these tests, the specimens, 75 mm square and up to 25 mm thick, are exposed to radiant heat with and without a pilot flame(s). Decomposition takes place inside a closed cabinet of 0.51 m3. There is no control of the air flow or oxygen concentration through the fire zone and the effluent is mixed by natural convection, as it accumulates within the closed cabinet. Gases are sampled using probes mounted in the center of the cabinet. 

There are a large number of different methods used for bench-scale assessment of combustion toxicity, and the applicability of test data to lire hazard assessment is not always clear. Obviously, toxic potency data should not be used in isolation but should either be a part of a classification scheme or as part of the input to lire risk and lire safety engineering assessments. It is important that uncertainty or confidence limits should be used with toxic potency data, because they are often relatively large. Fire effluent toxic potency does not have a unique value but is a function of the material and the fire conditions, particularly temperature and oxygen availability in the fire zone, and also the fire environment (enclosure, geometry, and ventilation). To assess the fire hazard, toxic potency data must be relevant to the end use fire situation, and the fire condition, which can be defined using the ISO classification of fire stages. 

Cordierite, 2 MgO. 2 AI2O3. 5 Si02, is a compound with an extraordinarily low expansion coefficient. The content of this phase is responsible for thermal expansion of cordierite ceramics and for its resistance to thermal shocks. Linear thermal expansion coefficient of about 15 x 10 (20-300 °C) is attainable. However, difficulties are again encountered on firing, because of the large amounts of melt formed at the liquidus temperature. A difference of only several degrees may have the result that a small fired object contains both porous (insufficiently fired) as well as fused (excessively fired) zones. 

The by-product steam is normally introduced with the air or oxygen to aid in the gasification reactions and to control the fire zone temperatures. 

The sources of informafion used to evaluate burner performance on commercial scale insfallafions fypically falls into one of three categories (i) combustion performance in the oxy-fuel fired zone, (ii) flue gas emissions from the furnace (including any parficulafe maffer), and... 

Zabetakis from LNG fires in 6-m square pools (Figure 48). In test 29-4, liquid carbon dioxide was sprayed into the fire zone after about 7 min the fire was not extinguished and the burning rate increased by a factor of 2 to 3. In test 29-5, similar results were obtained with water sprays. In still other tests, LNG fires were extinguished in the 6-m square pool by the use of 55-200 lb of sodium bicarbonate powder applied from turret nozzles. In the most efficient trials, flames were extinguished quickly by the use of 0.14 lb of powder per square foot per second over the entire surface larger application rates were required when less than the entire area was attacked at once. 

In order to produce safely and go over the fire zone successfully, mixed the FR-1 polymer liquid foam inhibitor and water according to the proportion of 1 2 (Xu 2010). Use special foam device to create the inhibitor foam. And then put out fire... 

Take B4-2 drilling of fire zone in Gu-Xin small coal mine as an illustration. CO concentration was... 

The results show that CO concentration and gas temperature decrease with injection time increased. The two indications reduced to the fire zone extinction standard of coal mine safety regulation within 4 to 5 days. That is to say air temperature of detection zone decreased to below 30°C, the oxygen concentration is reduced to below 5%, the concentration of carbon monoxide reduced to below 0.001%. Injecting FR-1 polymer liquid foam inhibitor played a significant role in eliminating the high temperature point and preventing coal mine fire. 

For all but the smallest facilities fire zones are used. They ensure that firefighting systems are used only in those areas that actually have a problem. Offshore platforms, e.g., are typically divided into... 

Figure 12.4 shows the use of fire zones. A ring main goes around the entire facility. It is filled with water whose pressure is maintained with a jockey pump. Connected to the ring main are multiple zones. The fire water headers in each zone are normally dry. In this example, there are two fire water pumps, each of which has sufficient capacity on its own to handle the design fire case. These pumps are placed in different locations at the facility so that, if one is destroyed, the other will provide a full flow of fire water. It is common for them to have different power supplies—in particular, one of them will be driven by a stand-alone diesel motor that operates independently of the facility s utility systems. 

To reduce fuel rates, the first fired zone should be controlled by temperature measurement in the roof about 6 ft from the uptake flue in the direction of load... 

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