For many years, the ZIL 131 vehicle remained the main platform for the creation of specialized fire fighting equipment in the Soviet Union and the post-Soviet space. The key element of any fire pumping station mounted on this chassis is centrifugal pump, which supplies high-pressure water to extinguish fires. The PNS 110 model (often referred to as PN-40 or PN-60 depending on the modification and year of manufacture, where the number indicates performance) is a reliable unit capable of operating in extreme conditions.
Understanding the design and operation of this equipment is critical to fire crew technicians and drivers. From serviceability suction and delivery hose to the correct operation of the vacuum pump - each component affects the effectiveness of fire extinguishing. In this article we will analyze in detail the PNS 110 device, its technical parameters, operating features based on the ZIL 131 and typical malfunctions.
General structure and purpose of the pumping station
The PNS 110 pumping station, installed on the ZIL 131 chassis, is a complex unit mounted in the rear of the body. The main purpose of the system is to collect water from open water sources or hydrants and supply it to the trunks or carriages under the required pressure. The design is based on a single-stage centrifugal pump with double-sided liquid supply to the impeller, which ensures high performance and flow stability.
The pump housing is usually made of aluminum alloy, which reduces the overall weight of the installation and improves heat transfer. The pump shaft is driven into rotation by the vehicle's internal combustion engine through a cardan drive and power take-off (PTO). An important element is the lubrication and cooling system, which often utilizes water from the pump itself to cool the bearing units, preventing them from overheating during prolonged operation.
When the pump operates for a long time at idle speed without water flow, be sure to open the circulation valves to prevent the liquid from boiling inside the housing.
The station also includes vacuum pump, necessary to create a vacuum and lift water from a source located below the level of the pump axis. All control elements, including pressure gauges, vacuum gauges and valve handles, are located in a convenient operator area, protected from high temperatures and mechanical damage. The reliability of the entire system directly depends on timely maintenance of seals and bearings.
Technical characteristics and operating parameters
The effectiveness of fire extinguishing directly depends on the compliance of the technical characteristics of the pump with the requirements of a particular situation. PNS 110, based on the ZIL 131, is designed to provide high performance while maintaining compact dimensions. The nominal capacity of the unit is 40 liters per second (corresponding to 2400 liters per minute) at a pressure of 100 meters of water column, however, depending on the modification, these parameters may vary.
The maximum suction lift at a water temperature of 20°C should not exceed 7.5 meters. Exceeding this value can lead to cavitation and a sharp drop in performance. The ZIL 131 engine provides sufficient torque to drive the pump even at low speeds, which allows you to save fuel when working to fill tanks or pump water over long distances.
Below is a table with the main technical data of the standard pump modification for your reference:
| Parameter | Meaning | Unit of measurement |
|---|---|---|
| Nominal capacity | 40 | l/s |
| Head at rated flow | 100 | m |
| Shaft speed | 2700 | rpm |
| Maximum suction lift | 7.5 | m |
| Vacuum creation time | 20-30 | sec |
It is important to note that actual performance may differ from the rated performance depending on the condition o-rings and wear of the impeller. Regular checking of parameters using calibrated pressure gauges allows you to quickly identify a decrease in the efficiency of the unit.
Operating principle and water movement pattern
The process of starting and operating a pumping station requires a clear understanding of the hydraulic circuit. Water enters through suction pipes equipped with check valves that prevent the outflow of liquid when the engine is stopped. Next, the flow is directed to the central part of the impeller, where, under the action of centrifugal force, it acquires kinetic energy and is released into the pressure chamber.
To start the water supply process it is used vacuum pump (often piston or water ring type). The operator opens the filling valve of the vacuum pump and starts its operation, creating a vacuum in the suction cavity. As soon as water enters the main pump housing, the vacuum pump turns off and normal circulation begins.
⚠️ Attention: It is strictly forbidden to turn on the vacuum pump if there is water in the main pump housing, as this will lead to water hammer and destruction of the blades of the vacuum unit.
Adjustment of pressure and productivity is carried out by changing the speed of the car engine crankshaft and the position of the valves on the pressure manifolds. The system allows operation in the mode of serial or parallel connection of sections (in two-stage modifications), which gives flexibility in choosing the operating mode depending on the type of fire.
What is cavitation and why is it dangerous?
Cavitation is the process of formation and collapse of vapor bubbles in a liquid. In the pump, this causes characteristic noise, vibration and erosion of the metal of the impeller, which quickly disables the unit.
Preparing for work and starting the system
Proper preparation of the PNS 110 pump for operation on the ZIL 131 base is the key to successful fire extinguishing. Before starting the operation, the driver is required to conduct an external inspection of the unit, check the oil levels in the pump crankcase and vacuum pump, and also make sure that there is no visible damage to the hose lines. Particular attention should be paid to the tightness of connections.
The starting process begins with engaging the clutch and activating the power take-off. The car engine warms up to operating temperature, after which the rotation speed gradually increases. The operator monitors the instrument readings: the pressure gauge needle should respond to changes in speed, and the vacuum gauge should show the creation of the required vacuum when the valves are closed.
☑️ Checklist before starting the pump
When working with open water sources, it is necessary to use mesh filter baskets at the ends of the suction hoses. This will prevent large debris, sand or silt from getting inside. flow part pump, which could cause the impeller to seize or damage the seals.
Typical faults and methods for their elimination
During operation, the PNS 110 pump may encounter a number of characteristic problems. One of the most common is a drop in productivity or pressure. This may be caused by wear and tear o-rings impeller, clogging of the suction mesh or air leakage through leaky hose connections. Diagnostics begins with checking the vacuum gauge: if the vacuum does not hold, you should look for leaks.
Another common problem is overheating of bearing units. The cause is often a lack of lubrication or poor circulation of cooling water inside the housing. If you notice an increase in bearing housing temperature above 60°C, you need to reduce the load and check the lubrication system.
List of main malfunctions and ways to eliminate them:
- 🔧 The pump does not create a vacuum - check the oil level in the vacuum pump, the tightness of the valves and the integrity of the piston group.
- 💧 Water leaking through the oil seals - the oil seal packing needs to be tightened or completely replaced with a new set.
- 📉 Low pressure at high speeds - the impeller is likely to wear out or there is an air lock in the system.
- 🔊 Extraneous noise and vibration - check the alignment of the shafts, the tightness of the mounting bolts and the absence of foreign objects in the impeller.
⚠️ Attention: If a leak is detected through the mechanical shaft seal, do not try to stop it by over-tightening the bolts, as this will lead to rapid wear of the graphite rings and jamming of the shaft.
Maintenance and care of the unit
The durability of the PNS 110 pump directly depends on the quality and regularity of maintenance. After each use, especially if the pump operated on water from open sources with sand or silt, it is necessary to flush the system with clean water. This will prevent sedimentation and corrosion of internal surfaces.
Routine maintenance includes changing the oil in the pump crankcase and vacuum unit according to the maintenance schedule, checking the condition of the oil seals and lubrication of the bearing units. Particular attention should be paid to the condition cardan transmissionconnecting the PTO and the pump: it is necessary to check the play in the crosspieces and the reliability of the flanges.
The main rule of longevity pump: never leave water in the pump housing for a long time without preservation, especially in winter, to avoid corrosion and rupture of the housing by ice.
During winter operation, special care is required. After completion of work, all water must be completely removed from the pump, hoses and pipelines through special drain holes. To do this, the pump is briefly put into operation with the drain taps open in order to displace the remaining water from hard-to-reach cavities.
Frequently asked questions (FAQ)
What is the maximum water temperature permissible for the PNS 110 pump?
Standard modifications of centrifugal fire pumps, including PNS 110, are designed to operate with water temperatures up to +35°C. However, for a short time they can pump water with temperatures up to +60°C, but this reduces the performance of the vacuum pump and increases the risk of cavitation. Long-term operation with hot water requires special seals.
How often should the oil in the pump crankcase be changed?
According to the maintenance regulations, the oil in the centrifugal pump crankcase is changed during seasonal maintenance (twice a year) or after every 100 operating hours. When operating in dusty conditions or when water gets into the crankcase (oil emulsification), replacement is carried out immediately.
Is it possible to use PNS 110 for pumping petroleum products?
The use of a standard fire pump PNS 110 for pumping petroleum products is strictly prohibited. Rubber seals, oil seals and gaskets are not designed to withstand aggressive liquids and may be damaged. In addition, there is a high risk of sparking and fuel vapor explosion.
What to do if the pump “hums” but does not pump water?
If the pump works, but no water flows, the tightness of the suction line is most likely broken (air leakage) or sufficient vacuum has not been created. Check the tightness of the clamps on the hoses, the water level in the source and the serviceability of the check valves. It is also possible that the suction screen is clogged.