Fire pump
Fire extinguishing pumps are flow machines specially designed for fire fighting for pumping water . They are mainly used by the fire department . There are also fire extinguishing pumps that are installed as a preventive fire protection for particularly endangered objects.
Types of fire pumps
Portable pumps
These pumps are T ragkraft s called syringe (TS), as they are carried to the respective place and are not installed permanently in a vehicle. In EN 1028 and EN 14710, they are defined as motor pumps that can be transported by manual force and are not permanently installed in a fire engine.
In German-speaking countries, portable pumps with a nominal delivery rate of between 800 l and 1600 l per minute are most common. It is also available as a bilge pump with a delivery rate of 2400 liters per minute at a delivery pressure of 3 bar. With the introduction of the new standard Tragkraftspritzen be in Germany as PFPN ( P ortable F your deleted p ump N ormaldruck, P ortable F ire P ump N denotes ormal pressure). There are new performance classes of 1000 liters at 10 bar (PFPN 10-1000), 1500 liters at 10 bar (PFPN 10-1500) or 2000 liters at 10 bar (PFPN 10-2000).
The portable pumps have their own motor, usually a gasoline engine , in rare cases a diesel engine . Act as a drive i. d. Usually adapted standard engines. The air-cooled industrial engine from VW was widely used in older West German models . The performance limit of these pumps is closely related to their weight, which should be able to be carried by four firefighters. This does not only apply on level ground, but also in steeper areas in the mountains. They have the advantage that they can be used away from the emergency vehicle to extract water from open waters .
Older models have a reversing starter or a crank , which is widespread in the new German federal states, as well as a starter rod in very old West German pumps.
Newer models have an electric starter , often supplemented with a reversing starter in case the electric starter does not work.
By using lightweight components (aluminum motors and support frames), modern pumps are more powerful, but not heavier than earlier models.
There are also special designs such as buoyant pumps or portable pumps that can be carried on the back, which can be used, for example, in forest fires.
The non-standardized pumps include the compact high-pressure extinguishing units, which combine the motor pump, rapid attack device and tank in one unit and thus give smaller fire-fighting vehicles or rescue vehicles extinguishing capacities for an initial attack in the event of small and incipient fires.
Built-in pumps
Built-in pumps are usually firmly integrated at the rear, sometimes in a device room on the right or left of the vehicle, in the tank fire trucks and fire fighting vehicles. They are with the vehicle engine via the power take-off driven. Depending on the performance, they have two to four pressure outputs and may be connected to a monitor mounted on the vehicle roof or a rapid attack device . On the suction side, they have a direct connection to a water tank and also an A suction connection. For pumps that have a high pressure part, this is provided directly with the rapid attack device and with a high pressure outlet.
Built-in pumps have an additional bypass line through which a small amount of water can always be pumped back into the water tank. This prevents the tank from freezing and the pump from overheating if no water is pumped for a long time. The water pumped in a circuit is slightly heated and prevents the formation of vapor bubbles ( cavitation ) in the pump , which could damage the pump.
New pumps are often completely disguised, the manual valves can be replaced by electrically or pneumatically controlled valves .
Airfield fire engines , as used by the airport fire brigade, have i. d. Usually its own motor to drive the pump. The delivery rate is large according to the application.
Pumps on the front of the vehicle
Front-mounted pump ( stem pumps , according to the standard in Germany Front pump called), which are driven by the vehicle engine are no longer provided for in the German standards for fire engines for several years. Accordingly, they are only of fire fighting vehicles of older design or vehicles from the civil protection available. A typical example of such a vehicle is the LF 16-TS , which has a portable pump in the rear instead of its own water tank. Such vehicles are used where there is no collective water supply. You can, however, take your water from any hydrant or feed it in from a fire truck and continue to pump the water.
They were developed primarily from experience of the Second World War, when extinguishing water had to be taken from lakes, rivers, ponds or bomb craters when the hydrant network collapsed.
Construction of fire pumps
Pump housing
- Single-stage centrifugal fire pump
- The delivery pressure is applied by a pressure stage and the delivery flow is fed directly to the pressure outlet via the helical ring channel. At higher speeds there is a risk of cavitation .
- Two-stage centrifugal fire pump
- The delivery pressure is generated by two pressure stages located close together. The diffuser and the impeller form a unit - a pressure stage. The delivery flow is provided with a partial pressure in the first pressure stage and passed into the second pressure stage. This second stage increases the partial pressure of the flow to the outlet pressure. Both impellers work on a drive shaft at the same speed. A two-stage pump is less prone to blistering.
- differences
- The only difference in the way they work is the speed. With the same delivery pressure, the speed of a single-stage pump is higher. The max. Delivery pressure is the same.
- Mode of action
- With the ventilation device, a negative pressure is generated in the suction hoses and the FP. The atmosphere pushes the water into the pump. The water hits the rotating impeller axially and is caught by the blades and accelerated outwards by centrifugal force. By expanding the impeller channels, the speed in the impeller is already partially converted into pressure energy. In the downstream diffuser, the duct cross-sections are also continuously increased so that the remaining speed up to the entry into the next stage is reduced so far that it corresponds to the entry speed of the first stage. As a result of this reduction in speed, the water in the distributor experiences an increase in pressure. The impeller and diffuser together form a stage. In the second stage, the same process is repeated as in the first stage. The pressure of the second stage is doubled compared to the first stage. Here, the impeller conveys the water into the helical ring channel, in which the speed reduction and thus the pressure increase take place due to the enlarged space. From here the water flows to the pressure outlets.
- Regularities
- When the pressure outlets are closed, the delivery pressure generated in the pump is greatest (delivery flow = 0). Delivery flow and delivery pressure are dependent on a certain amount. When the outlets are opened, the delivery pressure is lower and the delivery rate is greater. The greatest flow rate is achieved when the outflow is free, i.e. when the outlets are completely open. One of the properties of the FP that is important for pumping extinguishing water is that it only generates the pressure that it opposes as resistance. If the back pressure is higher, the flow rate is smaller; if the pressure is lower, it is larger. There is a small valve on the pump housing for emptying the water residue from the pump housing. This sits at the lowest point of the housing.
Ventilation device
Fire brigade centrifugal pumps are not self-priming, which means that they need a venting device to remove all air from the suction hoses and pump housing before starting suction operation. The surrounding air pressure then pushes the water to be sucked into the hoses and pump housing (see section on suction process ). Piston pumps or diaphragm pumps are widely used for this , and gas ejectors are used in older pumps . The exhaust gases from the engine are fed into an injector pump as propellant gas and the air is sucked out of the pump and the suction hoses according to the injector principle until they are vented.
The previously used liquid ring and dry ring ventilation devices have been replaced by piston pumps in today's centrifugal fire pumps. The simplest venting device is to fill the suction line and the pump housing with water. This requires a properly functioning check valve in the strainer . This method is comparatively cumbersome and is only used in practice if the built-in ventilation device fails.
Vent and vent valve
It sits between the pump housing and the ventilation device. If the pressure in the pump housing rises (when the pump starts to pump) the venting and venting valve closes automatically so that the water is not forced into the venting device.
manometer
A centrifugal fire pump has two pressure gauges (or three if there is a high pressure stage):
- The underpressure / overpressure manometer is used by the machinist to check the pump inlet pressure during use and as a control manometer for the dry suction test (see section "General"):
- In suction mode (water extraction from open water, cisterns , extinguishing water well) the needle falls into the left, red marked negative pressure area, by means of which the negative pressure in the suction line is displayed. The negative pressure depends on the geodetic suction height and the amount of water pumped.
- In operation with pump inlet pressure (water extraction hydrant , feeder pump , etc.), the needle moves into the overpressure area on the right, marked in black. The pump inlet pressure should not fall below 1.5 bar, as the automatic venting device - if available - starts the venting process again from this limit. In addition, if the pressure is too low, the water supply's pipeline network can be damaged. Depending on the type of pump, it should usually not exceed 3 bar, as otherwise the pump wheels could be overloaded in the wrong direction.
- The overpressure manometer indicates the pump outlet pressure. This will usually be 8 to 12 bar, but can vary depending on the purpose of use (supply of submersible turbo pump , foam insert ).
- If there is a high pressure stage, the measuring range is up to around 40 bar. If the high pressure stage is not switched on, the range can be identical to the first pressure gauge.
The pressure gauges of modern pumps have the bar as the unit of measurement , with older pumps the customary specification "mWS" for meters of water column was used at the time.
Function and operation
Suction process
When sucking in, the venting device evacuates the pump housing and the connected suction hoses.
This creates a pressure difference to the ambient pressure in the pump housing and in the suction line. Due to this pressure difference, the ambient pressure pushes the water from the outside into the suction line. The height of the water rising in the suction line depends on the pressure difference between the ambient pressure and the suction pressure.
Since the ambient pressure at sea level is on average around 1013 mbar absolute, i.e. around 1 bar absolute, and water has a density of 1 kg / dm³, the maximum theoretical suction height for pumps conveying water is 10 meters. Since there are (among other things) friction losses in all machines and there are leaks, the maximum suction height (which is common in practice) for fire extinguishing pumps is between 7 and 8 meters. This depends on factors such as air pressure (and thus altitude), flow speed through the pump (delivery rate) or temperature of the water.
When the suction pressure in the pump drops below the vapor pressure of the water, cavitation occurs in the pump .
When the water gets into the pump and the pump begins to deliver, the pressure in the pump housing rises and, in modern pumps, switches off the ventilation device via a device (e.g. a reciprocating piston). Older ventilation systems such as B. Gas emitters are switched on or off manually.
business
A centrifugal pump is a fluid flow machine for increasing energy by means of a rotating impeller. Liquid that gets into the pump is carried away by the rotating pump wheel and forced onto a circular path. On this path, the pressure built up by centrifugal force drives the liquid radially outwards, where it flows off through the drain. This mode of operation is called the hydrodynamic delivery principle.
Dry suction test
If a dry suction test is carried out after the operation of a fire extinguishing pump, a rough vacuum is generated with the aid of the venting device in order to check the pump for any leaks after operation. Errors can be defective seals or defective housings. The functionality of the ventilation device is also checked. This ensures that it will function properly for the next use.
The suction connection is closed by a blind coupling , the pressure outlets are closed (without blind couplings) and the pump is started. In the case of non-automatic venting devices, this is activated. The pump must generate a vacuum of at least 0.8 bar within 30 seconds. After the pump has been switched off, the vacuum may decrease by a maximum of 0.1 bar within one minute.
In the machines of some manufacturers, the dry suction test is also used to lubricate the pump elements with the aid of the stuffing boxes.
Types of use
Extinguishing water pumping over long distances
In principle, there are two different ways of transporting water over long distances, namely on the one hand the open and on the other hand the closed switching series.
In the open switching series, a pump pumps the water to a container (mostly partially inflatable collapsible containers, loaded onto LF 20 KatS , among others ), from which the next pump draws in the water and forwards it. One advantage of this procedure is that the pressure at which the water flows into the container can be above 3 bar or less than 1.5 bar. Disadvantages are the increased time and material requirements.
In the closed switching series, the first pump is connected directly to the following pump via hoses, which in turn is connected to another pump via hoses, etc. The advantages here are the quicker construction and the lower material requirement. A disadvantage is that the inlet pressure of the booster pump must be between 1.5 and 3 bar. To ensure this, either a pressure relief valve is used in front of the pump inlet or the outlet pressure is calculated with regard to the distance and the friction losses in the hose.
With built-in pumps it must be ensured that the contaminated water must not get into the water tank. It is essential to keep the bypass line closed. Otherwise the tank must be rinsed thoroughly afterwards. The reason for this is, on the one hand, that deposits of dirt in the tank are to be avoided, and on the other hand, in disaster control: the fire engines are filled with drinking water from the hydrant network. In the event of a disaster or defense, they should be able to provide support in securing the drinking water supply if necessary.
Pumping out z. B. basements or underground garages
Most (at least newer) built-in pumps have a setting for bilge operation. The highest possible flow rate is made possible with a very low outlet pressure. This is useful when pumping out full cellars or underground garages, where the outlet pressure is insignificant, but the greatest possible delivery rate is desired.
Operation of water-powered devices
Some newer design centrifugal fire pumps often also have special devices for operating water-powered devices. The water-driven fan is a good example. Here, pressures between 12 and 15 bar or more are required in order to be able to operate the fan sensibly. There is a special fan operating mode for the pump and an additional, mostly laterally built-in B-input for the return flow from the fan.
Fire pumps at German fire departments
The modern fire extinguishing pumps are centrifugal pumps (technical term: fire extinguishing centrifugal pump). They are either portable or permanently mounted on the fire engine as a front-mounted pump or in the rear of the vehicle. They belong to the group of fire service pumps, which are divided into pumps for pumping water and pumps for pumping other liquids. The term "fire brigade pumps" is defined: Fire brigade pumps are mechanically driven flow machines for pumping liquids.
Gottlieb Daimler manufactured the world's first gasoline engine-driven fire pump . He acquired the patent for this horse-drawn fire engine with motorized operation on July 29, 1888. The single-cylinder engine with an output of one horsepower was connected to a piston pump from the fire engine manufacturer Heinrich Kurtz through a reduction gear.
Classification of fire pumps
In Europe, the new portable fire-fighting centrifugal pumps are currently named in the same way as the built-in pumps according to EN. The name is for example "PFPN 10-1000" (PFPN = Portable Firepump Normal Pressure), which means "Portable fire-fighting centrifugal pump normal pressure with a nominal flow rate of 1000 l / min at a nominal flow pressure of 10 bar".
- Common fire fighting centrifugal pumps in Germany - old and new, according to DIN and DIN EN
(portable pumps may have different names)
- (withdrawn Norm) 14420 according to DIN: (scheme: abbreviation "FP" = " F your fighting centrifugal p ump" - nominal flow rate / 100 l / min and nominal delivery pressure in bar )
- FP 2/5 (centrifugal fire pump with a nominal flow rate of 200 l / min at a nominal flow pressure of 5 bar)
- FP 4/5 (centrifugal fire pump with a nominal flow rate of 400 l / min at a nominal flow pressure of 5 bar)
- FP 8/8 (fire fighting centrifugal pump with a nominal flow rate of 800 l / min at a nominal flow pressure of 8 bar)
- FP 16/8 (centrifugal fire pump with a nominal flow rate of 1600 l / min at a nominal flow pressure of 8 bar)
- FP 24/8 (centrifugal fire pump with a nominal flow rate of 2400 l / min at a nominal flow pressure of 8 bar)
- FP 32/8 (centrifugal fire pump with a nominal flow rate of 3200 l / min at a nominal flow pressure of 8 bar)
- Instead of "FP", portable pumps have the abbreviation "TS" for " T ragkraft s spritze"
- according to DIN EN 1028 (since 11/2002) (scheme: abbreviation "FP" = "fire pump" "N =" normal pressure "(or in English:" F ire P ump N ormal Pressure ") - nominal supply pressure in bar - nominal delivery rate in l / min)
- FPN 6-500 (fire extinguishing centrifugal pump as TS (in KLF according to the old standard) for normal pressure with a nominal flow rate of 500 l / min at a nominal flow pressure of 6 bar)
- FPN 10-1000 (fire-fighting centrifugal pump for normal pressure with a nominal flow rate of 1000 l / min at a nominal flow pressure of 10 bar)
- FPN 10-2000 (fire fighting centrifugal pump for normal pressure with a nominal flow rate of 2000 l / min at a nominal pressure of 10 bar)
- FPN 10-3000 (fire fighting centrifugal pump for normal pressure with a nominal flow rate of 3000 l / min at a nominal flow pressure of 10 bar)
- FPN 10-4000 (fire fighting centrifugal pump for normal pressure with a nominal flow rate of 4000 l / min at a nominal flow pressure of 10 bar)
- Portable pumps now the abbreviation "PFPN" for carrying " P ortable F ire P ump N ormal Pressure"
- use in accordance with standards
The current German fire fighting vehicle standards only provide for pumps of the following types: FPN 10-1000, FPN 10-2000, PFPN 10-1000, PFPN 10-1500 and PFPN 10-2000.
- connections
The TS 8/8 (new: PFPN 10-1000) has an A suction connection and two B pressure outlets as connections . For mountainous terrain or for self-protection units (authorities) and the military, there are lighter models (TS 4/5, TS 2/5 and TS 0.5 / 5) with correspondingly lower flow rates and lower pressure. They only have a B input or a C output.
Guarantee points
The guarantee points of today's centrifugal fire pumps define three performance values that a pump must at least meet. Since the performance varies depending on the suction height and water pumping, the following three points have been defined:
- According to EN 1028
- Guarantee point 1: Nominal flow rate at nominal pressure and a geodetic suction height of 3 meters at the nominal speed specified by the manufacturer
- Guarantee point 2: 50 percent of the nominal delivery rate at nominal delivery pressure and a geodetic suction height of 7.5 meters (at a speed of up to the maximum speed)
- Guarantee point 3: 50 percent of the nominal flow rate at 1.2 times the nominal flow pressure and a geodetic suction height of 3 meters (at a speed below the maximum speed)
| Guarantee point 1 | Guarantee point 2 | Guarantee point 3 |
| 1000l / min at 10 bar | 500l / min at 10 bar | 500l / min at 12 bar |
| 3 m | 7.5 m | 3m |
- According to the old DIN 14 420
- Guarantee point 1: Nominal flow rate at nominal pressure and a geodetic suction height of 3 meters at the nominal speed specified by the manufacturer.
- Guarantee point 2: 50 percent of the nominal flow rate at 1.5 times the nominal delivery pressure and a geodetic suction height of 3 meters (at max. 1.2 times the nominal speed)
- Guarantee point 3: 50 percent of the nominal delivery rate at nominal delivery pressure and a geodetic suction height of 7.5 meters (at a maximum of 1.4 times the nominal speed)
| Guarantee point 1 | Guarantee point 2 | Guarantee point 3 |
| 800l / min at 8 bar | 400l / min at 12 bar | 400l / min at 8 bar |
| 3 m | 3 m | 7.5 m |
It should be noted that the old DIN standard 14 420 has been replaced by a new European standard (EN 1028). In particular, guarantee points 2 and 3 were swapped.
literature
- Hans Schönherr: Die Roten Hefte, Heft 44a - Pumps in the fire brigade: Part I: Introduction to hydromechanics, mode of operation of centrifugal pumps . 4th edition. Kohlhammer, Stuttgart 1998, ISBN 978-3-17-015172-7 .
- Christian Schwarze: Die Rote Hefte, Heft 44b - Pumps in the fire brigade: Part II: Fire-fighting centrifugal pumps, additional equipment, pressure proportioning and compressed air foam systems . 5th edition. Kohlhammer, Stuttgart 2005, ISBN 978-3-17-018605-7 .
- Syringe testing standards. In: Fromme's Oesterreichischer Feuerwehr-Kalender , year 1878, fifth year, pp. 41–47 (yearbook). (Online at ANNO ). .
Web links
- Portable pumps from all over the world
- Portable pump IG
- Free extinguishing water supply calculation programs
Individual evidence
- ^ The red booklet 44b: Pumps in the fire brigade, edition 5, year 2005 ISBN 3-17-018605-1
- ↑ DIN EN 1028, fire pumps - centrifugal fire pumps with ventilation device, 2009.
- ↑ a b Training of volunteer fire brigades - machinist for fire engines, State Fire Brigade School Baden-Württemberg, Neckarverlag, 2002.
- ^ Franz-Josef Sehr : Development of fire protection . In: Freiwillige Feuerwehr Obertiefenbach e. V. (Ed.): 125 years of the Obertiefenbach volunteer fire brigade . Reference 2005, ISBN 978-3-926262-03-5 , pp. 114-119 .
- ↑ Jan Tino Demel, section work: The new pump standardization leads to changed pump characteristics (PDF; 1.0 MB), May / June 2009.