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The core of the fire protection system - the fire pump is the basis for the work of Isuzu fire fighting vehicles. Whether the performance of the fire pump is reliable directly affects whether the fire brigade can play its role in emergency situations and protect the safety of people's lives and property. The vehicle fire pump is a non-powered, movable fire pump installed on the chassis of the Isuzu fire truck. Vehicle fire pumps have special applications and need to have some of their own characteristics. Especially the adaptability of vehicle fire pumps to the working environment and the relationship between the vehicle chassis and vehicle fire pumps.

1. Requirements for fire pumps for Isuzu fire trucks:

A. Performance requirements for vehicle fire pumps: Vehicle fire pumps have special application occasions. When using fire pumps, due to emergency situations, water is needed in many places, and water consumption increases sharply. It is impossible to require operators to strictly follow the pump ratings. In normal operation, firefighters are likely to open the valve wide. At this time, the pump must ensure that the water pressure does not drop too much, so as not to affect the fire extinguishing effect. In addition, when water consumption is reduced, the pressure cannot be too high, otherwise hoses and pipe accessories with higher pressure resistance must be used, which will increase the investment a lot. Since the water consumption in the fire scene is high and low, the fire pump must be able to operate stably under both large flow and small flow. This actually requires that the lift-flow performance curve of the fire pump be relatively flat, so that the pump's lift will not drop significantly under large flow rates, the head will not be too high under small flow rates, and the working range will be wide.

B. Requirements for vehicle fire pumps to absorb water: As a mobile fire pump, there are great uncertainties in the installation height and working environment of vehicle fire pumps. Therefore, vehicle fire pumps must have a certain ability to divert water. . Vehicle fire pumps are required to meet the rated flow and rated pressure requirements when the suction depth is 3m. Suction depth refers to the height difference between the pump reference level and the suction liquid level. The so-called suction depth of 3m is 3m under the conditions of standard atmospheric pressure and water temperature of 20℃. When the air pressure deviates from the standard atmospheric pressure and the water temperature is not 20℃, it can be corrected by the suction depth correction formula. At the same time, the fire pump also needs to meet the requirement that the maximum suction depth is not less than 7m. When the fire vehicle is sucking at a depth of 7m, the water pump flow rate is not less than 50% of the rated flow rate.

C. Working characteristics of vehicle fire pumps under changing working conditions: Vehicle fire pumps must not only meet the requirements of rated flow and rated pressure when the suction depth is 3m, but also must meet the requirements of 50% of the rated flow and rated pressure when the suction depth is 7m. . For high-pressure pumps, they must meet the requirements of 70% of the rated flow rate and 130% of the rated pressure when the suction depth is 3m. Medium and high pressure pumps must meet the requirements of 50% high pressure rated flow and working pressure not less than 1.8MPa when the suction depth is 3m. High and high pressure pumps must meet the requirements of high pressure rated flow and rated pressure when the suction depth is 3m. And for medium-high pressure and high-pressure pumps, there should be joint working conditions of medium-high pressure and high-pressure.

D. Structural requirements for fire pumps for Isuzu fire trucks: An arrow indicating the direction of rotation should be cast on the pump body. The operating mechanism should be light and reliable. Each control handle should be equipped with an indicator plate, which should be made of anti-corrosion materials. The height of the text on the sign should not be less than 3mm, and the depth of pressing or etching should not be less than 0.2mm; a corrosion-resistant filter that is easy to disassemble should be installed at the pump suction inlet, and the flow area of the filter should not affect the performance of the pump. The pump should be equipped with a drain cock, which should be at the lowest position of the pump to drain the remaining water in the pump. The diameter of the drain cock should be no less than 19mm; the pump should be equipped with a pressure hole, and the diameter of the pressure hole should be 3-6mm or equal to 1/10 of the pipe diameter, whichever is smaller. The depth of the pressure tapping hole should be no less than 2.5 times the diameter of the pressure tapping hole, and the outlet pressure tapping hole should be located behind the check valve. It is specified in the material requirements that the pump casing should be made of cast iron, cast steel, cast aluminum or cast copper and other cast alloys. The shaft should be made of at least ZCrl3 stainless steel or equivalent corrosion-resistant material, or the shaft should be made of carbon steel, but a sleeve of corrosion-resistant material must be used in the stuffing box and the pump body flow passage; the impeller and impeller sealing ring , shell seal ring, collar, packing ring, water seal ring, packing gland, mechanical seal cover, packing sleeve, water bearing sleeve, block sleeve, intermediate bushing, pressure reducing bushing, sealing gland, gland Nuts, sleeve nuts, impeller nuts and drain cocks should be made of corrosion-resistant materials. Mechanical performance requires the pump to be pressurized to 1.1 times the sum of the maximum working pressure and the maximum allowable positive pressure at the inlet, and the pump casing to be pressurized to 2 times the sum of the maximum working pressure and the maximum allowable positive pressure at the inlet or 2.0MPa , whichever is greater of the two. The water diversion device should be tested for water diversion reliability. After 500 consecutive water diversions, it should still be able to meet the maximum vacuum degree and water diversion time requirements. For water diversion devices with automatic breakaway devices, the automatic breakaway devices shall work normally after passing the water diversion reliability test.

2. The relationship between vehicle fire pumps and Isuzu vehicle chassis: When fighting fires, we always hope that the water pumps of firefighting vehicles can operate at full load or even overload. However, the outage and damage caused by long-term overload operation of firefighting vehicles Failure will cause serious consequences of fire extinguishing failure.

The water pump power of Isuzu fire fighting vehicles can be calculated by the following formula:

Assume that when we supply water to a 120-meter high-rise building, the water pump power requires 73.42kw. When using a Isuzu fire truck with an Isuzu chassis, the power of the Isuzu fire truck chassis is 191kw. The Isuzu fire truck supplies water to a height of 160 meters. When the flow rate is 30L/s, the power The demand is 78.4kw, and the power that the Isuzu fire truck chassis can provide is 114kw. Therefore, without damaging the water pump, increasing the water pump speed can still tap the potential and improve the water supply capacity of the water pump.

Therefore, when we purchase fire-fighting vehicles, we should consider the power reserve of the vehicle chassis. The power selection cannot be based on the conventional rated power plus 10%-20% of the margin, but should comprehensively consider the large-flow starting power, maximum operation It is recommended that the margin should be more than 25%. In addition, the vehicle should also have a certain margin in terms of chassis carrying capacity and should not be over excavated.