Calculations of forces and means are performed in the following cases:
- when determining the required amount of forces and means to extinguish a fire;
- during operational-tactical study of an object;
- when developing fire extinguishing plans;
- in the preparation of fire-tactical exercises and classes;
- when carrying out experimental work to determine the effectiveness of extinguishing agents;
- in the process of investigating a fire to assess the actions of the RTP and units.
Calculation of forces and means for extinguishing fires of solid flammable substances and materials with water (spreading fire)
- characteristics of the object (geometric dimensions, nature of the fire load and its placement at the object, location of water sources relative to the object);
- time from the moment a fire occurs until it is reported (depends on the availability of the type of security equipment, communication and alarm equipment at the facility, the correctness of the actions of the persons who discovered the fire, etc.);
- linear speed of fire spread Vl;
- forces and means provided for by the schedule of departures and the time of their concentration;
- intensity of fire extinguishing agent supply Itr.
1) Determination of the time of fire development at various points in time.
The following stages of fire development are distinguished:
- 1, 2 stages free development of fire, and at stage 1 ( t up to 10 minutes) the linear speed of propagation is taken equal to 50% of its maximum value (tabular), characteristic of a given category of objects, and from a time of more than 10 minutes it is taken equal to the maximum value;
- Stage 3 is characterized by the beginning of the introduction of the first trunks to extinguish the fire, as a result of which the linear speed of fire propagation decreases, therefore, in the period of time from the moment the first trunks are introduced until the moment of limiting the spread of the fire (the moment of localization), its value is taken equal to 0,5 V l . When localization conditions are met V l = 0 .
- Stage 4 – fire extinguishing.
t St. = t update + t report + t Sat + t sl + t br (min.), where
- tSt.– time of free development of the fire at the time of arrival of the unit;
- tupdate – time of fire development from the moment of its occurrence to the moment of its detection ( 2 minutes.– in the presence of APS or AUPT, 2-5 min.– with 24-hour duty, 5 minutes.– in all other cases);
- treport– time of reporting a fire to the fire brigade ( 1 min.– if the telephone is located in the duty officer’s premises, 2 minutes.– if the telephone is in another room);
- tSat= 1 min.– time of gathering of personnel on alarm;
- tsl– travel time of the fire department ( 2 minutes. on 1 km of way);
- tbr– combat deployment time (3 minutes when feeding the 1st barrel, 5 minutes in other cases).
2) Distance determination R traversed by the combustion front during the time t .
at tSt.≤ 10 min:R = 0,5 ·Vl · tSt.(m);
at tbb> 10 min:R = 0,5 ·Vl · 10 + Vl · (tbb – 10)= 5 ·Vl + Vl· (tbb – 10) (m);
at tbb < t* ≤ tlok : R = 5 ·Vl + Vl· (tbb – 10) + 0,5 ·Vl· (t* – tbb) (m).
- Where t St. – time of free development,
- t bb – time at the moment of introduction of the first trunks for extinguishing,
- t lok – time at the time of localization of the fire,
- t * – the time between the moments of localization of the fire and the introduction of the first trunks for extinguishing.
3) Determination of the fire area.
Fire area S p – this is the area of the projection of the combustion zone onto a horizontal or (less often) vertical plane. When burning on several floors, the total fire area on each floor is taken as the fire area.
Fire perimeter R p – this is the perimeter of the fire area.
Fire front F p – this is part of the fire perimeter in the direction(s) of combustion propagation.
To determine the shape of the fire area, you should draw a scale diagram of the object and plot the distance from the location of the fire on a scale R traversed by fire in all possible directions.
In this case, it is customary to distinguish three options for the shape of the fire area:
- circular (Fig. 2);
- corner (Fig. 3, 4);
- rectangular (Fig. 5).
When predicting the development of a fire, it should be taken into account that the shape of the fire area may change. Thus, when the flame front reaches the enclosing structure or the edge of the site, it is generally accepted that the fire front straightens and the shape of the fire area changes (Fig. 6).
a) The area of the fire with a circular form of fire development.
SP= k · p · R 2 (m2),
- Where k = 1 – with a circular form of fire development (Fig. 2),
- k = 0,5 – with a semicircular shape of fire development (Fig. 4),
- k = 0,25 – with an angular form of fire development (Fig. 3).
b) Fire area for a rectangular fire development.
SP= n b · R (m2),
- Where n– number of directions of fire development,
- b– width of the room.
c) Fire area with a combined form of fire development (Figure 7)
SP = S 1 + S 2 (m2)
a) The area of fire extinguishing along the perimeter with a circular form of fire development.
S t = kp· (R 2 – r 2) = k ·p··h t · (2·R – h t) (m 2),
- Where r = R – h T ,
- h T – depth of extinguishing trunks (for hand trunks – 5 m, for fire monitors – 10 m).
b) Fire extinguishing area around the perimeter for a rectangular fire development.
ST= 2 hT· (a + b – 2 hT) (m2) – along the entire perimeter of the fire ,
Where A And b are the length and width of the fire front, respectively.
ST = n·b·hT (m 2) – along the front of the spreading fire ,
Where b And n – respectively, the width of the room and the number of directions for feeding the barrels.
5) Determination of the required water flow to extinguish the fire.
QTtr = SP · Itr – atS p ≤S t (l/s) orQTtr = ST · Itr – atS p >S t (l/s)
Intensity of supply of fire extinguishing agents I tr – this is the amount of fire extinguishing agent supplied per unit of time per unit of design parameter.
The following types of intensity are distinguished:
Linear – when a linear parameter is taken as a calculated parameter: for example, front or perimeter. Units of measurement – l/s∙m. Linear intensity is used, for example, when determining the number of shafts for cooling burning tanks and oil tanks adjacent to the burning one.
Superficial – when the fire extinguishing area is taken as a design parameter. Units of measurement – l/s∙m2. Surface intensity is used most often in fire extinguishing practice, since in most cases water is used to extinguish fires, which extinguishes the fire along the surface of burning materials.
Volumetric – when the extinguishing volume is taken as a design parameter. Units of measurement – l/s∙m3. Volumetric intensity is used primarily for volumetric fire extinguishing, for example, with inert gases.
Required I tr – the amount of fire extinguishing agent that must be supplied per unit of time per unit of the calculated extinguishing parameter. The required intensity is determined based on calculations, experiments, statistical data based on the results of extinguishing real fires, etc.
Actual I f – the amount of fire extinguishing agent that is actually supplied per unit of time per unit of the calculated extinguishing parameter.
6) Determining the required number of guns for extinguishing.
A)NTst = QTtr / qTst– according to the required water flow,
b)NTst= R p / R st– along the perimeter of the fire,
R p - part of the perimeter for extinguishing which guns are inserted
R st =qst / Itr ∙ hT- part of the fire perimeter that is extinguished with one barrel. P = 2 · p L (circumference), P = 2 · a + 2 b (rectangle)
V) NTst = n (m + A) – in warehouses with rack storage (Fig. 11) ,
- Where n – number of directions of fire development (introduction of trunks),
- m – number of passages between burning racks,
- A – the number of passages between the burning and adjacent non-burning racks.
7) Determining the required number of compartments for supplying barrels for extinguishing.
NTdepartment = NTst / nst department ,
Where n st department – the number of barrels that one compartment can supply.
8) Determination of the required water flow for the protection of structures.
Qhtr = Sh · Ihtr(l/s),
- Where S h – protected area (floors, coverings, walls, partitions, equipment, etc.),
- I h tr = (0,3-0,5) ·I tr – intensity of water supply to protection.
9) The water yield of a ring water supply network is calculated using the formula:
Q to the network = ((D/25) V in) 2 [l/s], (40) where,
- D – diameter of the water supply network, [mm];
- 25 is a conversion number from millimeters to inches;
- V in is the speed of movement of water in the water supply system, which is equal to:
- – at water supply pressure Hв =1.5 [m/s];
- – with water supply pressure H>30 m water column. –V in =2 [m/s].
The water yield of a dead-end water supply network is calculated using the formula:
Q t network = 0.5 Q to network, [l/s].
10) Determination of the required number of trunks to protect structures.
Nhst = Qhtr / qhst ,
Also, the number of barrels is often determined without analytical calculation for tactical reasons, based on the location of the barrels and the number of protected objects, for example, one fire monitor for each farm, and one RS-50 barrel for each adjacent room.
11) Determination of the required number of compartments for supplying trunks to protect structures.
Nhdepartment = Nhst / nst department
12) Determining the required number of compartments to perform other work (evacuation of people, material valuables, opening and dismantling of structures).
Nldepartment = Nl / nl department , NMCdepartment = NMC / nMC department , NSundepartment = SSun / SSun dept.
13) Determination of the total required number of branches.
Ngenerallydepartment = NTst + Nhst + Nldepartment + NMCdepartment + NSundepartment
Based on the results obtained, the RTP concludes that the forces and means involved in extinguishing the fire are sufficient. If the forces and means are not enough, then the RTP makes a new calculation at the time of arrival of the last unit at the next increased number (rank) of the fire.
14) Comparison of actual water consumption Q f for extinguishing, protection and drainage of the network Q water fire water supply
Qf = NTst· qTst+ Nhst· qhst ≤ Qwater
15) Determination of the number of ACs installed on water sources to supply the calculated water flow.
Not all the equipment that arrives at a fire is installed at water sources, but only the amount that would ensure the supply of the calculated flow rate, i.e.
N AC = Q tr / 0,8 Q n ,
Where Q n – pump flow, l/s
This optimal flow rate is checked according to accepted combat deployment schemes, taking into account the length of the hose lines and the estimated number of barrels. In any of these cases, if conditions permit (in particular, the pump-hose system), combat crews of arriving units should be used to operate from vehicles already installed at water sources.
This will not only ensure the use of equipment at full capacity, but will also speed up the deployment of forces and means to extinguish the fire.
Depending on the fire situation, the required consumption of fire extinguishing agent is determined for the entire fire area or for the fire extinguishing area. Based on the results obtained, the RTP can conclude that the forces and means involved in extinguishing the fire are sufficient.
Calculation of forces and means for extinguishing fires with air-mechanical foam in an area
(fires that do not spread or conditionally lead to them)
Initial data for calculating forces and means:
- fire area;
- intensity of supply of foaming agent solution;
- intensity of water supply for cooling;
- estimated extinguishing time.
In case of fires in tank farms, the design parameter is taken to be the area of the liquid surface of the tank or the largest possible area of flammable liquid spillage during fires on aircraft.
At the first stage of combat operations, the burning and neighboring tanks are cooled.
1) The required number of barrels to cool a burning tank.
N zg stv = Q zg tr / q stv = n ∙ π ∙ D mountains ∙ I zg tr / q stv , but not less than 3 trunks,
Izgtr= 0.8 l/s ∙ m – required intensity for cooling a burning tank,
Izgtr= 1.2 l/s ∙ m – required intensity for cooling a burning tank during a fire in ,
Tank cooling W res ≥ 5000 m 3 and it is more expedient to carry out fire monitors.
2) The required number of barrels for cooling the adjacent non-burning tank.
N zs stv = Q zs tr / q stv = n ∙ 0,5 ∙ π ∙ D SOS ∙ I zs tr / q stv , but not less than 2 trunks,
Izstr = 0.3 l/s ∙ m is the required intensity for cooling the adjacent non-burning tank,
n– the number of burning or neighboring tanks, respectively,
Dmountains, DSOS– diameter of the burning or adjacent tank, respectively (m),
qstv– productivity of one (l/s),
Qzgtr, Qzstr– required water flow for cooling (l/s).
3) Required number of GPS N gps to extinguish a burning tank.
N gps = S P ∙ I r-or tr / q r-or gps (PC.),
SP– fire area (m2),
Ir-ortr– required intensity of supply of foam agent solution for extinguishing (l/s∙m2). At t vsp ≤ 28 o C I r-or tr = 0.08 l/s∙m 2, at t vsp > 28 o C I r-or tr = 0.05 l/s∙m 2 (see Appendix No. 9)
qr-orgps – GPS productivity for foaming agent solution (l/s).
4) Required amount of foaming agent W By to extinguish the tank.
W By = N gps ∙ q By gps ∙ 60 ∙ τ R ∙ K z (l),
τ R= 15 minutes – estimated extinguishing time when applying high-frequency MP from above,
τ R= 10 minutes – estimated extinguishing time when applying high-frequency MP under the fuel layer,
K z= 3 – safety factor (for three foam attacks),
qBygps– capacity of the gas station for foaming agent (l/s).
5) Required amount of water W V T to extinguish the tank.
W V T = N gps ∙ q V gps ∙ 60 ∙ τ R ∙ K z (l),
qVgps– GPS productivity for water (l/s).
6) Required amount of water W V h for cooling tanks.
W V h = N h stv ∙ q stv ∙ τ R ∙ 3600 (l),
Nhstv– total number of trunks for cooling tanks,
qstv– productivity of one fire nozzle (l/s),
τ R= 6 hours – estimated cooling time for ground tanks from mobile fire fighting equipment (SNiP 2.11.03-93),
τ R= 3 hours – estimated cooling time for underground tanks from mobile fire fighting equipment (SNiP 2.11.03-93).
7) The total required amount of water for cooling and extinguishing tanks.
WVgenerally = WVT + WVh(l)
8) Approximate time of possible release T of petroleum products from a burning tank.
T = ( H – h ) / ( W + u + V ) (h), where
H – initial height of the flammable liquid layer in the tank, m;
h – height of the bottom (commercial) water layer, m;
W – linear speed of heating of the flammable liquid, m/h (tabular value);
u – linear burnout rate of flammable liquid, m/h (tabular value);
V – linear speed of level decrease due to pumping, m/h (if pumping is not performed, then V = 0 ).
Extinguishing fires in premises with air-mechanical foam by volume
In case of fires in premises, they sometimes resort to extinguishing the fire using a volumetric method, i.e. fill the entire volume with air-mechanical foam of medium expansion (ship holds, cable tunnels, basements, etc.).
When supplying HFMP to the volume of the room there must be at least two openings. Through one opening, the VMP is supplied, and through the other, smoke and excess air pressure are displaced, which contributes to better advancement of the VMF in the room.
1) Determination of the required amount of GPS for volumetric extinguishing.
N gps = W pom ·K r/ q gps ∙ t n , Where
W pom – volume of the room (m 3);
K p = 3 – coefficient taking into account the destruction and loss of foam;
q gps – foam consumption from GPS (m 3 /min.);
t n = 10 min – standard fire extinguishing time.
2) Determining the required amount of foaming agent W By for volumetric extinguishing.
WBy = Ngps ∙ qBygps ∙ 60 ∙ τ R∙ K z(l),
Hose capacity
Appendix No. 1
Capacity of one rubberized hose 20 meters long depending on diameter
|
Throughput, l/s |
Sleeve diameter, mm |
|||||
| 51 | 66 | 77 | 89 | 110 | 150 | |
| 10,2 | 17,1 | 23,3 | 40,0 | – | – | |
Application № 2
Resistance values of one pressure hose 20 m long
| Sleeve type | Sleeve diameter, mm | |||||
| 51 | 66 | 77 | 89 | 110 | 150 | |
| Rubberized | 0,15 | 0,035 | 0,015 | 0,004 | 0,002 | 0,00046 |
| Non-rubberized | 0,3 | 0,077 | 0,03 | – | – | – |
Application № 3
Volume of one sleeve 20 m long
Appendix No. 4
Geometric characteristics of the main types steel vertical tanks (RVS).
| No. | Tank type | Tank height, m | Tank diameter, m | Fuel surface area, m2 | Tank perimeter, m |
| 1 | RVS-1000 | 9 | 12 | 120 | 39 |
| 2 | RVS-2000 | 12 | 15 | 181 | 48 |
| 3 | RVS-3000 | 12 | 19 | 283 | 60 |
| 4 | RVS-5000 | 12 | 23 | 408 | 72 |
| 5 | RVS-5000 | 15 | 21 | 344 | 65 |
| 6 | RVS-10000 | 12 | 34 | 918 | 107 |
| 7 | RVS-10000 | 18 | 29 | 637 | 89 |
| 8 | RVS-15000 | 12 | 40 | 1250 | 126 |
| 9 | RVS-15000 | 18 | 34 | 918 | 107 |
| 10 | RVS-20000 | 12 | 46 | 1632 | 143 |
| 11 | RVS-20000 | 18 | 40 | 1250 | 125 |
| 12 | RVS-30000 | 18 | 46 | 1632 | 143 |
| 13 | RVS-50000 | 18 | 61 | 2892 | 190 |
| 14 | RVS-100000 | 18 | 85,3 | 5715 | 268 |
| 15 | RVS-120000 | 18 | 92,3 | 6691 | 290 |
Appendix No. 5
Linear velocities of combustion propagation during fires at facilities.
| Object name | Linear speed of combustion propagation, m/min |
| Administrative buildings | 1,0…1,5 |
| Libraries, archives, book depositories | 0,5…1,0 |
| Residential buildings | 0,5…0,8 |
| Corridors and galleries | 4,0…5,0 |
| Cable structures (cable burning) | 0,8…1,1 |
| Museums and exhibitions | 1,0…1,5 |
| Printing houses | 0,5…0,8 |
| Theaters and Palaces of Culture (stages) | 1,0…3,0 |
| Combustible coatings for large workshops | 1,7…3,2 |
| Combustible roof and attic structures | 1,5…2,0 |
| Refrigerators | 0,5…0,7 |
| Woodworking enterprises: | |
| Sawmill shops (buildings I, II, III SO) | 1,0…3,0 |
| The same, buildings of IV and V degrees of fire resistance | 2,0…5,0 |
| Dryers | 2,0…2,5 |
| Procurement shops | 1,0…1,5 |
| Plywood production | 0,8…1,5 |
| Premises of other workshops | 0,8…1,0 |
| Forest areas (wind speed 7...10 m/s, humidity 40%) | |
| Pine forest | up to 1.4 |
| Elnik | up to 4.2 |
| Schools, medical institutions: | |
| Buildings of I and II degrees of fire resistance | 0,6…1,0 |
| Buildings of III and IV degrees of fire resistance | 2,0…3,0 |
| Transport facilities: | |
| Garages, tram and trolleybus depots | 0,5…1,0 |
| Hangar repair halls | 1,0…1,5 |
| Warehouses: | |
| Textile products | 0,3…0,4 |
| Paper in rolls | 0,2…0,3 |
| Rubber products in buildings | 0,4…1,0 |
| The same in stacks in an open area | 1,0…1,2 |
| Rubber | 0,6…1,0 |
| Inventory assets | 0,5…1,2 |
| Round timber in stacks | 0,4…1,0 |
| Lumber (boards) in stacks at a humidity of 16...18% | 2,3 |
| Peat in stacks | 0,8…1,0 |
| Flax fiber | 3,0…5,6 |
| Rural settlements: | |
| Residential area with dense buildings of fire resistance class V, dry weather | 2,0…2,5 |
| Thatched roofs of buildings | 2,0…4,0 |
| Litter in livestock buildings | 1,5…4,0 |
Appendix No. 6
Intensity of water supply when extinguishing fires, l/(m 2 .s)
| 1. Buildings and structures | |
| Administrative buildings: | |
| I-III degree of fire resistance | 0.06 |
| IV degree of fire resistance | 0.10 |
| V degree of fire resistance | 0.15 |
| basements | 0.10 |
| attic spaces | 0.10 |
| Hospitals | 0.10 |
| 2. Residential buildings and outbuildings: | |
| I-III degree of fire resistance | 0.06 |
| IV degree of fire resistance | 0.10 |
| V degree of fire resistance | 0.15 |
| basements | 0.15 |
| attic spaces | 0.15 |
| 3.Livestock buildings: | |
| I-III degree of fire resistance | 0.15 |
| IV degree of fire resistance | 0.15 |
| V degree of fire resistance | 0.20 |
| 4.Cultural and entertainment institutions (theatres, cinemas, clubs, palaces of culture): | |
| scene | 0.20 |
| auditorium | 0.15 |
| utility rooms | 0.15 |
| Mills and elevators | 0.14 |
| Hangars, garages, workshops | 0.20 |
| locomotive, carriage, tram and trolleybus depots | 0.20 |
| 5.Industrial buildings, areas and workshops: | |
| I-II degree of fire resistance | 0.15 |
| III-IV degree of fire resistance | 0.20 |
| V degree of fire resistance | 0.25 |
| paint shops | 0.20 |
| basements | 0.30 |
| attic spaces | 0.15 |
| 6. Combustible coatings of large areas | |
| when extinguishing from below inside a building | 0.15 |
| when extinguishing from outside from the coating side | 0.08 |
| when extinguishing from outside when a fire has developed | 0.15 |
| Buildings under construction | 0.10 |
| Trade enterprises and warehouses | 0.20 |
| Refrigerators | 0.10 |
| 7. Power plants and substations: | |
| cable tunnels and mezzanines | 0.20 |
| machine rooms and boiler rooms | 0.20 |
| fuel supply galleries | 0.10 |
| transformers, reactors, oil circuit breakers* | 0.10 |
| 8. Hard materials | |
| Paper loosened | 0.30 |
| Wood: | |
| balance at humidity, %: | |
| 40-50 | 0.20 |
| less than 40 | 0.50 |
| lumber in stacks within one group at humidity, %: | |
| 8-14 | 0.45 |
| 20-30 | 0.30 |
| over 30 | 0.20 |
| round timber in stacks within one group | 0.35 |
| wood chips in piles with a moisture content of 30-50% | 0.10 |
| Rubber, rubber and rubber products | 0.30 |
| Plastics: | |
| thermoplastics | 0.14 |
| thermosets | 0.10 |
| polymer materials | 0.20 |
| textolite, carbolite, plastic waste, triacetate film | 0.30 |
| Cotton and other fiber materials: | |
| open warehouses | 0.20 |
| closed warehouses | 0.30 |
| Celluloid and products made from it | 0.40 |
| Pesticides and fertilizers | 0.20 |
* Supply of finely sprayed water.
Tactical and technical indicators of foam supply devices
| Foam supply device | Pressure at the device, m | Concentration of solution, % | Consumption, l/s | Foam ratio | Foam production, m cubic/min (l/s) | Foam supply range, m | ||
| water | BY | software solution | ||||||
| PLSK-20 P | 40-60 | 6 | 18,8 | 1,2 | 20 | 10 | 12 | 50 |
| PLSK-20 S | 40-60 | 6 | 21,62 | 1,38 | 23 | 10 | 14 | 50 |
| PLSK-60 S | 40-60 | 6 | 47,0 | 3,0 | 50 | 10 | 30 | 50 |
| SVP | 40-60 | 6 | 5,64 | 0,36 | 6 | 8 | 3 | 28 |
| SVP(E)-2 | 40-60 | 6 | 3,76 | 0,24 | 4 | 8 | 2 | 15 |
| SVP(E)-4 | 40-60 | 6 | 7,52 | 0,48 | 8 | 8 | 4 | 18 |
| SVP-8(E) | 40-60 | 6 | 15,04 | 0,96 | 16 | 8 | 8 | 20 |
| GPS-200 | 40-60 | 6 | 1,88 | 0,12 | 2 | 80-100 | 12 (200) | 6-8 |
| GPS-600 | 40-60 | 6 | 5,64 | 0,36 | 6 | 80-100 | 36 (600) | 10 |
| GPS-2000 | 40-60 | 6 | 18,8 | 1,2 | 20 | 80-100 | 120 (2000) | 12 |
Linear rate of burnout and heating of hydrocarbon liquids
| Name of flammable liquid | Linear burnout rate, m/h | Linear speed of fuel heating, m/h |
| Petrol | Up to 0.30 | Up to 0.10 |
| Kerosene | Up to 0.25 | Up to 0.10 |
| Gas condensate | Up to 0.30 | Up to 0.30 |
| Diesel fuel from gas condensate | Up to 0.25 | Up to 0.15 |
| A mixture of oil and gas condensate | Up to 0.20 | Up to 0.40 |
| Diesel fuel | Up to 0.20 | Up to 0.08 |
| Oil | Up to 0.15 | Up to 0.40 |
| Fuel oil | Up to 0.10 | Up to 0.30 |
Note: with an increase in wind speed to 8-10 m/s, the rate of burnout of flammable liquid increases by 30-50%. Crude oil and fuel oil containing emulsified water may burn out at a higher rate than indicated in the table.
Changes and additions to the Guidelines for extinguishing oil and oil products in tanks and tank farms
(information letter of the GUGPS dated May 19, 2000 No. 20/2.3/1863)
Table 2.1. Standard rates of supply of medium expansion foam for extinguishing fires of oil and petroleum products in tanks
Note: For oil with impurities of gas condensate, as well as for oil products obtained from gas condensate, it is necessary to determine the standard intensity in accordance with current methods.
Table 2.2. Standard intensity of low expansion foam supply for extinguishing oil and oil products in tanks*
| No. | Type of petroleum product | Standard intensity of supply of foaming agent solution, l m 2 s’ | |||||
| Fluorine-containing foaming agents are “non-film-forming” | Fluorosynthetic “film-forming” foaming agents | Fluoroprotein “film-forming” foaming agents | |||||
| to the surface | per layer | to the surface | per layer | to the surface | per layer | ||
| 1 | Oil and petroleum products with a temperature of 28° C and below | 0,08 | – | 0,07 | 0,10 | 0,07 | 0,10 |
| 2 | Oil and petroleum products with a temperature of more than 28 °C | 0,06 | – | 0,05 | 0,08 | 0,05 | 0,08 |
| 3 | Stable gas condensate | 0,12 | – | 0,10 | 0,14 | 0,10 | 0,14 |
Main indicators characterizing the tactical capabilities of fire departments
The firefighting manager must not only know the capabilities of the units, but also be able to determine the main tactical indicators:
- ;
- possible extinguishing area with air-mechanical foam;
- possible volume of extinguishing with medium expansion foam, taking into account the available foam concentrate on the vehicle;
- maximum distance for supplying fire extinguishing agents.
Calculations are given in accordance with the Fire Fighting Manager's Handbook (RFC). Ivannikov V.P., Klyus P.P., 1987
Determining the tactical capabilities of a unit without installing a fire truck at a water source
1) Definition formula for operating time of water trunks from a tanker:
tslave= (V c –N p V p) /N st ·Q st ·60(min.),
N p =k· L/ 20 = 1.2·L / 20 (PC.),
- Where: tslave– operating time of the barrels, min.;
- V c– volume of water in the tank, l;
- N r– number of hoses in the main and working lines, pcs.;
- V r– volume of water in one sleeve, l (see appendix);
- N st– number of water trunks, pcs.;
- Q st– water consumption from the trunks, l/s (see appendix);
- k– coefficient taking into account terrain unevenness ( k= 1.2 – standard value),
- L– distance from the fire site to the fire truck (m).
Additionally, we draw your attention to the fact that in the RTP directory there are Tactical capabilities of fire departments. Terebnev V.V., 2004 in section 17.1 provides exactly the same formula but with a coefficient of 0.9: Twork = (0.9Vc – Np Vp) / Nst Qst 60 (min.)
2) Definition formula for possible extinguishing area with water STfrom a tanker:
ST= (V c –N p V p) / J trtcalculation· 60(m2),
- Where: J tr– required intensity of water supply for extinguishing, l/s m 2 (see appendix);
- tcalculation= 10 min. – estimated extinguishing time.
3) Definition formula for operating time of foam supply devices from a tanker:
tslave= (V solution –N p V p) /N gps Q gps 60 (min.),
- Where: V solution– volume of aqueous solution of foaming agent obtained from the filling tanks of the fire truck, l;
- N gps– number of GPS (SVP), pcs;
- Q gps– consumption of foaming agent solution from GPS (SVP), l/s (see appendix).
To determine the volume of an aqueous solution of a foaming agent, you need to know how much water and foaming agent will be consumed.
KV = 100–C / C = 100–6 / 6 = 94 / 6 = 15.7– the amount of water (l) per 1 liter of foaming agent to prepare a 6% solution (to obtain 100 liters of a 6% solution, 6 liters of foaming agent and 94 liters of water are required).
Then the actual amount of water per 1 liter of foaming agent is:
K f = V c / V by ,
- Where V c– volume of water in the fire truck tank, l;
- V by– volume of foam agent in the tank, l.
if K f< К в, то V р-ра = V ц / К в + V ц (l) – the water is completely consumed, but part of the foaming agent remains.
if K f > K in, then V solution = V in ·K in + V in(l) – the foaming agent is completely consumed, and some of the water remains.
4) Determination of possible formula for the area of extinguishing flammable liquids and gases air-mechanical foam:
S t = (V solution –N p V p) / J trtcalculation· 60(m2),
- Where: S t– extinguishing area, m2;
- J tr– required intensity of supply of PO solution for extinguishing, l/s·m2;
At t vsp ≤ 28 o C – J tr = 0.08 l/s∙m 2, at t vsp > 28 o C – J tr = 0.05 l/s∙m2.
tcalculation= 10 min. – estimated extinguishing time.
5) Definition formula for the volume of air-mechanical foam, received from the AC:
V p = V solution K(l),
- Where: V p– volume of foam, l;
- TO– foam ratio;
6) Defining what is possible air-mechanical extinguishing volume foam:
V t = V p / K z(l, m 3),
- Where: V t– volume of fire extinguishing;
- K z = 2,5–3,5 – foam safety factor, taking into account the destruction of high-frequency MP due to exposure to high temperature and other factors.
Examples of problem solving
Example No. 1. Determine the operating time of two shafts B with a nozzle diameter of 13 mm at a head of 40 meters, if one hose d 77 mm is laid before the branching, and the working lines consist of two hoses d 51 mm from AC-40(131)137A.
Solution:
t= (V c –N r V r) /N st Q st 60 = 2400 – (1 90 + 4 40) / 2 3.5 60 = 4.8 min.
Example No. 2. Determine the operating time of the GPS-600, if the head of the GPS-600 is 60 m, and the working line consists of two hoses with a diameter of 77 mm from the AC-40 (130) 63B.
Solution:
K f = V c / V po = 2350/170 = 13.8.
Kf = 13.8< К в = 15,7 for a 6% solution
V solution = V c / K in + V c = 2350/15.7 + 2350» 2500 l.
t= (V solution –N p V p) /N gps ·Q gps ·60 = (2500 – 2 90)/1 6 60 = 6.4 min.
Example No. 3. Determine the possible extinguishing area of medium expansion VMP gasoline from AC-4-40 (Ural-23202).
Solution:
1) Determine the volume of the aqueous solution of the foaming agent:
K f = V c / V po = 4000/200 = 20.
Kf = 20 > Kv = 15.7 for a 6% solution,
V solution = V in ·K in + V in = 200·15.7 + 200 = 3140 + 200 = 3340 l.
2) Determine the possible extinguishing area:
S t = V solution / J trtcalculation·60 = 3340/0.08 ·10 ·60 = 69.6 m2.
Example No. 4. Determine the possible volume of fire extinguishing (localization) with medium expansion foam (K=100) from AC-40(130)63b (see example No. 2).
Solution:
VP = Vsolution· K = 2500 · 100 = 250000 l = 250 m 3.
Then the volume of extinguishing (localization):
VT = VP/K z = 250/3 = 83 m 3.
Determining the tactical capabilities of a unit with the installation of a fire truck at a water source
Rice. 1. Scheme of water supply for pumping
| Distance in sleeves (pieces) | Distance in meters |
| 1) Determination of the maximum distance from the fire site to the lead fire truck N Goal ( L Goal ). | |
 |
 |
| N mm ( L mm ), working in pumping (length of the pumping stage). | |
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| N st | |
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| 4) Determination of the total number of fire engines for pumping N auto | |
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|
| 5) Determination of the actual distance from the fire site to the lead fire truck N f Goal ( L f Goal ). | |
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 |
- H n = 90÷100 m – pressure at the AC pump,
- H development = 10 m – pressure loss in branching and working hose lines,
- H st = 35÷40 m – pressure in front of the barrel,
- H input ≥ 10 m – pressure at the inlet to the pump of the next pumping stage,
- Z m – the greatest height of ascent (+) or descent (–) of the terrain (m),
- Z st – maximum height of ascent (+) or descent (–) of trunks (m),
- S – resistance of one fire hose,
- Q – total water consumption in one of the two busiest main hose lines (l/s),
- L – distance from the water source to the fire site (m),
- N hands – distance from the water source to the fire in the hoses (pcs.).
Example: To extinguish the fire, it is necessary to supply three trunks B with a nozzle diameter of 13 mm, the maximum height of the rise of the trunks is 10 m. The nearest water source is a pond located at a distance of 1.5 km from the place of the fire, the rise of the terrain is uniform and amounts to 12 m. Determine the number of AC tank trucks 40(130) for pumping water to extinguish a fire.
Solution:
1) We accept the method of pumping from pump to pump along one main line.
2) We determine the maximum distance from the fire site to the lead fire truck in the hoses.
N GOAL = / SQ 2 = / 0.015 10.5 2 = 21.1 = 21.
3) We determine the maximum distance between fire trucks working in pumping in the hoses.
NMR = / SQ 2 = / 0.015 10.5 2 = 41.1 = 41.
4) Determine the distance from the water source to the fire site, taking into account the terrain.
N P = 1.2 · L/20 = 1.2 · 1500 / 20 = 90 sleeves.
5) Determine the number of pumping stages
N STUP = (N P − N GOL) / N MP = (90 − 21) / 41 = 2 steps
6) Determine the number of fire trucks for pumping.
N AC = N STUP + 1 = 2 + 1 = 3 tank trucks
7) We determine the actual distance to the lead fire truck, taking into account its installation closer to the fire site.
N GOL f = N R − N STUP · N MP = 90 − 2 · 41 = 8 sleeves.
Consequently, the lead vehicle can be brought closer to the fire site.
Methodology for calculating the required number of fire trucks to transport water to the fire extinguishing site
If the building is combustible, and the water sources are located at a very large distance, then the time spent on laying hose lines will be too long, and the fire will be fleeting. In this case, it is better to transport water by tanker trucks with parallel pumping. In each specific case, it is necessary to solve a tactical problem, taking into account the possible scale and duration of the fire, the distance to water sources, the concentration speed of fire trucks, hose trucks and other features of the garrison.
AC water consumption formula (min.) – time of AC water consumption at the fire extinguishing site;
- L – distance from the fire site to the water source (km);
- 1 – minimum number of ACs in reserve (can be increased);
- V move – average speed of AC movement (km/h);
- W cis – volume of water in AC (l);
- Q p – average water supply by the pump that fills the AC, or water flow from a fire pump installed on a fire hydrant (l/s);
- N pr – number of water supply devices to the place of fire extinguishing (pcs.);
- Q pr – total water consumption from water supply devices from the AC (l/s).
Rice. 2. Scheme of water supply by delivery by fire trucks.
The supply of water must be uninterrupted. It should be borne in mind that it is necessary (mandatory) to create a point for filling tankers with water at water sources.
Example. Determine the number of AC-40(130)63b tank trucks for transporting water from a pond located 2 km from the fire site, if for extinguishing it is necessary to supply three trunks B with a nozzle diameter of 13 mm. Tank trucks are refueled by AC-40(130)63b, the average speed of tank trucks is 30 km/h.
Solution:
1) Determine the travel time of the AC to the fire site or back.
t SL = L 60 / V MOVE = 2 60 / 30 = 4 min.
2) Determine the time for refueling tank trucks.
t ZAP = V C /Q N · 60 = 2350 / 40 · 60 = 1 min.
3) Determine the time of water consumption at the fire site.
t EXP = V C / N ST · Q ST · 60 = 2350 / 3 · 3.5 · 60 = 4 min.
4) Determine the number of tank trucks to transport water to the fire site.
N AC = [(2t SL + t ZAP) / t EXP] + 1 = [(2 · 4 + 1) / 4] + 1 = 4 tank trucks.
Methodology for calculating water supply to a fire extinguishing site using hydraulic elevator systems
In the presence of swampy or densely overgrown banks, as well as at a significant distance to the water surface (more than 6.5-7 meters), exceeding the suction depth of the fire pump (high steep bank, wells, etc.), it is necessary to use a hydraulic elevator for water intake G-600 and its modifications.
1) Determine the required amount of water V SIST required to start the hydraulic elevator system:
VSIST = NR ·VR ·K ,
NR= 1.2·(L + ZF) / 20 ,
- Where NR− number of hoses in the hydraulic elevator system (pcs.);
- VR− volume of one hose 20 m long (l);
- K− coefficient depending on the number of hydraulic elevators in a system powered by one fire engine ( K = 2– 1 G-600, K =1,5 – 2 G-600);
- L– distance from AC to water source (m);
- ZF– actual height of water rise (m).
Having determined the required amount of water to start the hydraulic elevator system, compare the result obtained with the water supply in the fire tanker and determine the possibility of starting this system into operation.
2) Let us determine the possibility of joint operation of the AC pump with the hydraulic elevator system.
And =QSIST/ QN ,
QSIST= NG (Q 1 + Q 2 ) ,
- Where AND– pump utilization factor;
- QSIST− water consumption by the hydraulic elevator system (l/s);
- QN− fire truck pump supply (l/s);
- NG− number of hydraulic elevators in the system (pcs.);
- Q 1 = 9,1 l/s – operating water consumption of one hydraulic elevator;
- Q 2 = 10 l/s - supply from one hydraulic elevator.
At AND< 1 the system will work when I = 0.65-0.7 will be the most stable joint and pump.
It should be borne in mind that when drawing water from great depths (18-20m), it is necessary to create a pressure of 100 m on the pump. Under these conditions, the operating water flow in the systems will increase, and the pump flow will decrease against normal and it may turn out that the amount of operating and the ejected flow rate will exceed the pump flow rate. The system will not work under these conditions.
3) Determine the conditional height of water rise Z USL for the case when the length of hose lines ø77 mm exceeds 30 m:
ZUSL= ZF+ NR· hR(m),
Where NR− number of sleeves (pcs.);
hR− additional pressure losses in one hose on a section of the line over 30 m:
hR= 7 m at Q= 10.5 l/s, hR= 4 m at Q= 7 l/s, hR= 2 m at Q= 3.5 l/s.
ZF – actual height from the water level to the axis of the pump or tank neck (m).
4) Determine the pressure on the AC pump:
When taking water with one G-600 hydraulic elevator and ensuring the operation of a certain number of water trunks, the pressure on the pump (if the length of rubberized hoses with a diameter of 77 mm to the hydraulic elevator does not exceed 30 m) is determined by table 1.
Having determined the conditional height of water rise, we find the pressure on the pump in the same way according to table 1 .
5) Determine the maximum distance L ETC for the supply of fire extinguishing agents:
LETC= (NN– (NR± ZM± ZST) / S.Q. 2 ) · 20(m),
- Where HN− pressure at the fire truck pump, m;
- NR− pressure at the branch (assumed equal to: NST+ 10), m;
- ZM − height of ascent (+) or descent (−) of the terrain, m;
- ZST− height of ascent (+) or descent (−) of trunks, m;
- S− resistance of one branch of the main line
- Q− total flow rate from the shafts connected to one of the two most loaded main lines, l/s.
Table 1.
Determination of the pressure on the pump when water is taken by the G-600 hydraulic elevator and the operation of the shafts according to the corresponding schemes for supplying water to extinguish a fire.
6) Determine the total number of sleeves in the selected pattern:
N R = N R.SYST + N MRL,
- Where NR.SIST− number of hoses of the hydraulic elevator system, pcs;
- NMRL− number of branches of the main hose line, pcs.
Examples of solving problems using hydraulic elevator systems
Example. To extinguish a fire, it is necessary to apply two barrels to the first and second floors of a residential building, respectively. The distance from the fire site to the AC-40(130)63b tank truck installed on a water source is 240 m, the elevation of the terrain is 10 m. The access of the tank truck to the water source is possible at a distance of 50 m, the height of the water rise is 10 m. Determine the possibility of water intake by the tank truck and supplying it to the trunks to extinguish the fire.
Solution:
Rice. 3 Scheme of water intake using the G-600 hydraulic elevator
2) We determine the number of hoses laid to the G−600 hydraulic elevator, taking into account the unevenness of the terrain.
N Р = 1.2· (L + Z Ф) / 20 = 1.2 · (50 + 10) / 20 = 3.6 = 4
We accept four arms from AC to G−600 and four arms from G−600 to AC.
3) Determine the amount of water required to start the hydraulic elevator system.
V SYST = N P V P K = 8 90 2 = 1440 l< V Ц = 2350 л
Therefore, there is enough water to start the hydraulic elevator system.
4) We determine the possibility of joint operation of the hydraulic elevator system and the tank truck pump.
I = Q SYST / Q N = N G (Q 1 + Q 2) / Q N = 1 (9.1 + 10) / 40 = 0.47< 1
The operation of the hydraulic elevator system and the tanker pump will be stable.
5) We determine the required pressure on the pump to draw water from the reservoir using a G−600 hydraulic elevator.
Since the length of the hoses to G−600 exceeds 30 m, we first determine the conditional height of water rise: Z 
Water is the most effective means of fighting fires. Therefore, installation is a cost-effective measure aimed at preventing or localizing fire.
Types of fire containers
A fire tank is a container filled with water, designed taking into account established fire standards and requirements. When designing a reservoir, the characteristics of the protected object and the climatic features of the area are taken into account. Based on this, there are 3 types of fire containers:
- underground;
- aboveground;
- semi-underground.
Fire tanks can be made from brick, steel, stone, reinforced concrete or sheet building material.
Components of a fire tank
Each fire container must be equipped with the following elements:
- ventilation systems;
- pipelines for fluid inlet and outlet;
- overflow devices;
- hatches for repair work;
- plums;
- ladders or brackets;
- liquid level indicators.
It is important to take care of the safety and integrity of the reservoir by considering means of protection against mechanical stress and other external factors. For this purpose, hydro- and heat-insulating materials are used. A container made of metal must be grounded.
An obligatory means in arranging a fire reservoir (regardless of whether it is artificial or natural) is to ensure free access for vehicles.
Calculation of the capacity of fire reservoirs
Filling and maintaining a certain volume of water in the reservoir is especially important if it is not possible to extinguish the fire using a direct water supply.
The fire reservoir must contain the required volume of liquid to ensure:
- special fire extinguishing systems - deluge, sprinkler, etc.
- meeting household and industrial needs while fighting fire;
- extinguishing the flame using external hydrants or internal taps.
To determine the exact amount of water required in the tank, the following factors must be taken into account:
- speed of water supply from the reservoir;
- the time during which the flame is extinguished;
- the average number of fire cases in a particular period;
- tank filling speed.
When calculating the capacity of a fire reservoir and the average water consumption, three times the fire extinguishing time using the largest reservoir, as well as the cooling of the remaining containers, are taken into account.
Based on the data obtained, it is possible to determine the number and volume of fire tanks on the site.
Conclusion:
The pipe material is cast iron (2, clause 8.21), adopts a ring network, the length of repair sections with two water supply lines should be no more than 5 km (2, clause 8.10), the depth of the pipes, counting to the bottom, should be 0, 5 m more than the calculated soil freezing depth (2, clause 8.42). The SG should be installed along the road at a distance of no more than 2.5 m from the edge of the roadway (2, clause 8.16), but no closer than 5 m from the walls of the building; it is allowed to place the SG on the roadway (2, clause 8.16), while installing the SG on branching is not allowed (2, clause 8.16); when determining the size of wells, the minimum distance to the internal surfaces of the well should be taken according to GOST (2, clause 8.63).
CALCULATION OF PRESSURE - REGULATING CAPACITIES
Calculation of clean water tanks
The clean water reservoir (CWT) serves as a control and reserve tank and is located between the lift stations NS-I and NS-II.
Determine the volume of RHF
W RFV = W reg RFV + W n.z RFV – W eastern RFV
Determine control volume
The control volume is designed to regulate the water supply discrepancy
Determine the untouchable volume
W n.c = W fire + W cold. + W ave.
1). Fire reserve.
We accept t carcasses = 3 hours (2, clause 2.24)
2). Household and drinking supplies.
The emergency reserve for household and drinking needs can be calculated by the amount of water consumed during the maximum water consumption per period equal to the operating time of fire extinguishing. If t carcasses = 3 hours and K hour. Max. =1.7, then three hours of highest consumption from 11 00 to 14 00. At this time, for household and drinking needs of the settlement. 5.5+7+7=19.5% of daily water consumption is consumed
3) Production stock.
W n.c = W fire + W cold. + W pr. = 756.0 + 1186.4 + 540 = 2482.4 m 3
Determine the recovered volume of waterW east RHF
0.125 ∙ Q day.max = 0.125 ∙ 10404 = 1300.5 m 3
Determine the total volume of clean water tanks
W RFV = W reg RFV + W n.z RFV – W eastern RFV = 2077.7+2482.4–1300.5 = 3260 m 3
Determine the total number of RHFs and the volume of one of them
W 1 RFV ≥ W RFV ∙ 1/n,
We accept n=3 (1, clause 9.21)
Select standard tanks
I choose 3 tanks with a volume of 1200 m3
Brands and main parameters of tanks
Draw a conclusion
The number of fire tanks must be at least two (2, clause 9.29), and each of them must store 50% of the volume of water for fire extinguishing (2, clause 9.29). Tanks should be made of reinforced concrete (4, p. 275). Tanks must be equipped with a drain pipeline for supplying and withdrawing water, draining excess water, and discharging dirty water during repairs (4, p. 275).
Water towers (WT) are designed for:
Regulating uneven water consumption;
Storage of fire-fighting water reserves;
Creating the necessary pressure in the network.
WB tank capacity:
W tank = W reg. + W n.c.
Determine the regulating volume of the WB tank
The regulating volume of the WB tank serves to equalize uneven water consumption throughout the day:
A is the difference between the maximum and minimum values of the remaining water in the WB. At K hour. Max. = 1.7 A = 5.0% (Table 7).
Determination of the control volume of a water tower tank
|
Hours of the day |
Feed NS-1, % |
Admission to RCHV, % |
Consumption from RHF, % |
Remaining in RCHV, % |
Feed NS-2, % |
Admission to the World Bank, % |
Consumption from the World Bank, % |
Balance in WB, % |
Water consumption by the village, % |
The volume of fire water reserve (W pr) is determined from the water storage conditions required for:
Foam extinguishing for 15 minutes (0.4 hours) (clause 3 appendix 3 SNiP 2.11.03-93)
W 1 = 0.4 x 18.8 x 3.6 = 27.072 m 3
Irrigation with water (cooling) for 6 hours (clause 8.16 SNiP 2.11.03-93)
W 2 = 6 x (38.13 + 21.46) x 3.6 = 1287.144 m 3
Collecting water from hydrants for 3 hours (clause 2.24 SNiP 2.04.02-84*).
W 3 = 3 x 0.25x(38.13 + 21.46 + 18.8) x 3.6 = 211.653 m3
W pr = W 1 + W 2 + W 3 = 27.072 + 1287.144 + 211.653 = 1525.869 ≈ 1526 m 3.
We accept for installation two RVS-1000 tanks, each with a volume of 1000 m3. The tanks are heated with district heating water. The water temperature in the tanks is maintained at plus 10 degrees C.
The standard recovery time for the fire volume in tanks is assumed to be 24 hours (clause 2.25 of SNiP 2.04.02-84*) and is carried out through the designed ring drinking water supply at a rate of supply of at least
1526 / 24 = 63.58 m 3 /hour = 17.66 l/s (8.67 l/s in each tank).
The throughput capacity of the pipeline, taking into account the reduction in water consumption for household and drinking needs of the enterprise to 70% (note 2, clause 2.25 of SNiP 2.04.02-84*), will be:
63.58 + 0.7 x 2.285 = 65.18 m 3 / h = 18.01 l/sec
2.4 Selection of fire pumps
We select a pump for supplying water from reservoirs to the ring fire water supply according to the following data:
Pump capacity Q = 99.7 l/s ≈ 360 m 3 / h;
The pressure in front of the monitors and foam generators is nominal 60 m (working 40-80 m);
Diameter of suction lines – 400 mm
Diameter of pressure lines – 250 mm
The length of the pipeline from the PS to the most distant consumer is 0.8 km;
(along the ring, with the possible shutdown of one section for repairs - 1.1 km)
H = 60 + 1.2 x L x 1000i = 60 + 1.2 x 0.8 x 19.9 = 79.1 ≈80 m;
H = 60 + 1.2 x L x 1000i = 60 + 1.2 x 1.1 x 19.9 ≈ 86 m.
We accept for installation three pumping units (2 working; 1 standby) of the 1D200-90 brand (D K = 270 mm) with a 5AM250M2U3 electric motor with a power of 90 kW. The operating range of the pump in terms of productivity is from 140 to 250 m 3 /h. The maximum flow rate we need, 360 m 3 /h, will be provided by two pumps when operating in parallel with a pressure of 92 m of water. Art.
2.5 Selection of circulation pumps
In order to prevent freezing of water in the ring pipeline, its circulation is ensured and returned to the tanks at a temperature not lower than plus 5 degrees C.
The performance of the pumps and the thickness of the thermal insulation of the pipelines of the above-ground ring fire-fighting water supply system are taken by the selection method from the condition of preventing the formation of an ice crust in the pipe and from the calculation of preventing the water temperature in the pipeline from decreasing below plus 5 degrees C according to the method set out in SN 510-78.
Let us determine the water temperature at the beginning of the pressure water pipeline if the formation of an ice crust in the pipe is not allowed. Radius of steel water pipe r= 0.125 m. Length of the ring conduit l = 1600 m. Water consumption G=10000 kg/h. Thermal insulation of the pipe - shell made of thick polyurethane foam d u = 0.06 m; thermal conductivity coefficient of polyurethane foam l and = 0.028 W/(m×°C). Minimum average daily air temperature t V = - 57° C. Wind speed v= 7.7 m/s. Water speed in a pipeline DN 250 mm at a given flow rate vв = 0.057 m/s.
At a given water temperature at the end of the design section of the pipeline tk = 5 degrees C and the thickness of the thermal insulation d and, water temperature at the beginning of the calculated section t must be no less
t n = (t To - t V) e j z + t V ,
Where t c - minimum average daily outside air temperature, °C;
e - exponent (exponential function)
a c - heat transfer coefficient from water to the inner walls of the pipe, W/m 2 × ° C), determined by the formula
a n - heat transfer coefficient from the surface of the pipeline and the outside air, Wt/(m 2 ×°C), determined depending on the outer radius (with insulation) and wind speed
v - wind speed, m/s.
Using the above formulas we determine the values
a b = 1415 x 0.057 0.8 / (2x0.125) 0.2 = 188.74 W/(m×°C)
R in = 1 / (2x2.14x188.74 x 0.125) = 0.006746 m×°C/W
a n = 37 x 7.7 0.8 / 0.2 = 231.076 W/(m 2 ×°C)
R n = 1 /2x3.14 (0.125 +0.1)x 231.076 + 1 /2x3.14x0.028 x ln[(0.125 + 0.06)/ 0.125] = 2.232 m×°C/W
φ 3 = 1600 / 1.16x10000x (0.06746 + 2.232) = 0.0616
t n = (5-(-57)) e 0.07 + (-57) = 8.94 ° C
Thus, the initial temperature is 10 degrees. C is enough so that with a circulation flow rate of 10 m 3 / hour and a PU foam insulation thickness of 60 mm, the temperature at the end of the ring pipeline drops no lower than + 5 degrees C.
We will accept for installation pumps of the Irtysh-TsML 50/130-1.5/2 brand with a capacity of 10 m 3 /hour, a head of 21 m, in the amount of 3 pieces (1 working, 2 standby), in accordance with clause 7.3 of SN 510-78.
3 Operational section
3.1 Description of the fire extinguishing scheme
3.1. Calculation of the amount of fire extinguishing agents in the tank.
In tank farms of special equipment, as a rule, fire extinguishing with air-mechanical foam of medium expansion should be provided. Powder compositions, aerosol spray water and other extinguishing agents and methods may be provided, justified by the results of scientific research and agreed upon in the prescribed manner.
Fire extinguishing at ELV can be carried out by the following installations:
stationary automatic fire extinguishing, stationary non-automatic fire extinguishing and mobile. The choice of fire extinguishing installations should be provided depending on the capacity of the fire extinguishing system, the volume of installed individual tanks, the location of the fire extinguishing system, the organization of fire protection at the emergency vehicle, or the possibility of concentrating the required amount of fire equipment from fire stations located nearby within a radius of 3 km.
A stationary automatic foam fire extinguishing installation consists of:
From the pumping station;
Points for preparing a foaming agent solution;
Tanks for water and foaming agent;
Foam generators installed on the tanks in the upper part;
Dosing equipment;
Pipelines for supplying foam concentrate solution to foam generators;
Automation tools.
A stationary installation of non-automatic foam fire extinguishing on ground tanks consists of the same elements as a stationary automatic one, with the exception of automation equipment.
Mobile installation - fire trucks and a motor pump, as well as means for supplying foam. Water supply is provided from an external water supply network, fire-fighting tanks or natural water sources.
The choice of foam fire extinguishing installation is determined on the basis of technical and economic calculations.
Fire extinguishing agents are calculated based on the intensity of supply of chemical foam, based on the fire extinguishing time. The intensity of supply of fire extinguishing agents is their quantity per unit area (l/s ∙ m2).
Duration of submission, i.e. The estimated fire extinguishing time is the time it takes to supply fire extinguishing agents until it is completely eliminated at a given supply intensity.
To determine the water requirement for the formation of chemical foam, a multiplicity factor is used, showing the ratio of the volume of foam to the volume of water used for its formation (the multiplicity for chemical foam is: k = 5).
Water and foam lines of the fire extinguishing system are calculated based on water flow, the speed of which should not exceed v = 1.5 m/s.
The length of the foam pipelines should be in the range l = 40 – 80 m.
The amount of water in reserve is taken to be at least 5 times the water consumption for fire extinguishing and cooling of tanks.
Determination of the surface area of the oil product in the RVS - 10000 m 3
where D is the diameter of the tank, m
Substituting the value, we get
Fp = ------ = 6.38 m2
Determining the amount of chemical foam supplied to extinguish a fire in a tank using the formula:
Qn = q n sp ∙ Fp ∙ τ ∙ K z.v.
Where Qn is the total amount of foam to extinguish the fire, m 3;
q n beat – foam supply intensity, l/s ∙ m 2 (for diesel fuel
take q n beat = 0.2 l/s ∙ m 2)
Fp is the surface area of the oil product in the tank, m2, 60 –
transfer min. in sec.; 0.001 – conversion of volume from l to m3;
To z.v. – reserve factor of foaming substances
(assuming = 1.25)
τ - extinguishing time, hour. (assuming = 25)
Substituting the values, we get:
Qn = 60/1000 ∙ 0.2 ∙ 638(Fp) ∙ 25 ∙ 1.25 = 241 m 3
Determining the amount of water to form foam:
Where K is the expansion factor for chemical foam
(accept = 5)
Qв = 241/5 = 48 m 3
Determination of water consumption for cooling the burning tank and neighboring tanks (water must be spent on cooling the walls of the burning tank and neighboring tanks located at a distance of less than 2 diameters from the burning tank; cooling is carried out with water jets from fire hoses).
Determination of water consumption for cooling a burning tank:
Q v.g.r. = 3600/1000 ∙ Lp ∙ q sp.v.g. ∙ τ oh.g.
Where 3600 is the conversion of hours to seconds, 1000 is the conversion of l. in m 3
Lp - tank circumference, m
(L = π ∙ D = 3.14 ∙ 28.5 = 89.5 m)
q sp.v.g – specific water consumption for cooling the walls
burning tank, l/m ∙ s (assume = 0.5)
τ oh.g. - cooling time of a burning tank, hour.
(accept = 10 hours)
Substituting the values, we get:
Q v.g.r. = 3600/1000 ∙ Lp ∙ Np ∙ q sp.v.s. ∙ τ o.s.
Where Np is the number of neighboring tanks at a distance of less than
2 diameters (in each case N = 3 is taken)
τ is the cooling time of the adjacent tank, hour.