.png)
Characteristics of Fire Fighting Pumps
1. Fire Pumps & Pressure Pumps
Fire pumps are designed to pump water at high pressure (up to 6000 psi) over long distances, while pressure pumps operate at low pressures (around 1000-2000 psi). Both types of pumps utilize a motor to turn a shaft which drives the impeller/piston combination. A valve controls the flow rate and direction of the fluid.
2. Water Flow Rate Control Valve Types
There are two basic types of valves for controlling water flow rates: ball check valves and globe valves. Ball check valves consist of a ball which fits inside of a housing. When open, the ball rests freely in its housing; when closed, the ball contacts the wall of the housing and prevents flow. Globe valves have a spherical body that rotates to change the direction of the water flow. In both cases, the opening and closing of the valve is controlled by a mechanical actuation system.
3. Motor Driven Impellers
The impeller in a fire pump is driven by a belt drive connected to the motor shaft via a pulley. The impeller is fixed to the shaft, causing the impeller blades to rotate, drawing fluid into the pump and pushing it out again. The impeller design varies depending on the application. Smaller pumps need less force to overcome friction losses and can be operated at higher speeds. Larger pumps require larger forces to overcome friction losses and may only run at lower speeds.
4. Exterior vs Interior Impellers
Exterior impellers are mounted externally on the pump casing, where they are exposed to air. Because they do not contact the fluid directly, external impellers have no risk of contamination. However, since they cannot move back and forth for cleaning, their performance may decrease if they become clogged. Interior impellers are located inside the pump, where they are protected from outside contaminants. Since they do not move, they do not need any maintenance.
5. Pulsation Valves
Pulsation valves are used in fire pumps to control the discharge characteristics of the pump. They are particularly useful in systems with varying requirements. If the system requires constant discharge, pulsation valves are unnecessary. If the system requires only occasional discharge, pulsation valves allow the operator to set minimum and maximum discharge rates. Pulsation valves are generally rated according to the number of pulses per minute (ppm).
6. Air Check Valves
Air check valves prevent air from entering the discharge line. When the valve is closed, the fluid pushes past the seal and enters the line, bypassing the air. If the valve is opened, the fluid passes through the valve and down the line. Air check valves are often referred to as “air-in” or “air-out” valves.
7. Relief Valves
Relief valves are used to maintain a specific operating range within the limits of the regulator. They release excess pressure from the system if necessary. Most relief valves consist of a spring-loaded diaphragm that closes off the outlet port when the pressure rises above a certain limit. When the pressure drops below a certain point, the spring pulls the diaphragm away from the outlet port, enabling the liquid to exit the system. As a result, the pressure does not rise dangerously high. If left unchecked, high levels of pressure could cause damage to the equipment.
1. Fire pump characteristics
Firepumps are designed to generate high pressure water flow (up to 3000 psi) at low cost. These pumps are widely used for fighting fires due to their reliability and long life cycle. Pumps have different types including piston engine, turbine engine, centrifugal impeller, gearbox, vane-type, roller diaphragm and hydraulic diaphragms. Each type offers unique advantages and disadvantages. Advantages of fire pumper includes high flow rate, compact size, good performance. Disadvantages includes higher initial cost, maintenance cost, noise level, mechanical complexity, etc.
2. Pump selection criteria
The selection criteria for different types of fire pumps is based on various factors such as; power consumption, efficiency, durability, noise level, volume capacity, speed, and price. All these parameters should be considered while buying fire pumps.
3. Types of fire pump
There are three major types of firepump namely- Centrifugal Impeller, Gear box, Vane-Type, Roller Diaphragm, Hydraulic Diaphragm and Piston Engine. The following table shows the technical specifications and operating characteristic of each type of fire pump.
4. Operating characteristic of fire pump
Pumping action of fire pump is achieved by rotating impellers inside the pump chamber. As the pump rotates, water flows out of the bottom of the pump under pressure and passes through openings in the impeller blades. Water exits the pump via a discharge outlet located near the top of the pump housing.
5. Characteristic of fire pump
High pressure water generated by fire pump provides great advantage to fight fires effectively. High pressure water creates a turbulent stream of water that produces fast spreading flames and suppresses fire spread. Fire pump helps in extinguishing fire even after small amounts of fuel remain. In addition, it produces less smoke than conventional methods of firefighting. However, use of fire pump may cause injury to people if not properly trained.
6. Cost of fire pump
One of the important factor that affects the purchase decision of the pump is its cost. A fire pump costs about $50 to $500 depending upon its size. Generally, the larger and heavier pump becomes expensive. So, it is necessary to consider the size and weight of the pump prior to purchasing the same.
7. Maintenance cost of fire pump
Maintenance cost depends mainly on the number of hours of operation, pump wear and tear, and usage of replacement parts. The lifetime of a pump normally depends upon its design and application. If the pump is subjected to heavy duty work, then it is prone to damage and breakdown. Maintenance cost of fire pumps increases with increase in service time. Therefore, it is advisable to maintain a regular check on the pump status and replace worn parts before they become damaged.
Fire Pumping Systems: High pressure water systems that use pressurized water to create high velocity streams of water under extreme conditions such as extinguishing fires. There are two types of pumping systems - single stage and dual stage. A single stage system consists of a single pump, while a double stage system includes two pumps in series.
Firefighting pumps are a kind of pump that uses water to extinguish fires. These are mainly designed for use in industrial applications, however they are also often used in emergency situations like building fires.
There are two types of pumps commonly used in these circumstances - centrifugal pumps and jet-type pumps. Centrifugal pumps have a rotating impeller that extracts water from a source, then forces the water outward along a helical path at high velocity. Jet-type pumps have a similar construction except that the pumping mechanism comprises a series of nozzles aimed directly at the area being put out. The purpose of both types of pumps is to move the water rapidly around the fire, removing oxygen and fuel to reduce the rate of combustion.
The type of pump selected for a particular application is based on several factors, including cost, efficiency, reliability, size, and durability. Different types of pumps may have different advantages and disadvantages; for example, jet-type pumps tend to be much smaller than centrifugal pumps, but they may not extract water as effectively.
Centrifugal pumps can handle higher pressures than jet pumps; however, if the pressure exceeds a certain point, the pump cannot operate efficiently anymore, so care must be taken to ensure the pressure never becomes too high.
A typical firefighting pump consists of three parts: a motor housing, a drive shaft, and a pump body. The motor housing contains the electrical and mechanical components of the machine. A centrifugal pump consists of a casing, which encloses the blades contained inside the pump and is connected to a drive shaft. The shaft drives the impeller, which creates a partial vacuum inside the pump and moves water through pipes to a discharge nozzle. The flow rates and pressure achievable vary widely between different pumps, but some standard sizes are defined by international standards organizations. Pumps manufactured to meet international standards are generally interchangeable across manufacturers.
The performance characteristics of a pump depend largely upon its operating conditions. In fact, the major difference between a good pump and a bad pump is how well they perform under normal operating conditions. Performance can deteriorate over time due to aging, wear, corrosion, or damage, so regular maintenance is necessary to prevent problems and protect the integrity of the equipment. Maintenance includes cleaning, greasing, aligning, replacing worn parts, and adjusting settings, among others.
Pump manufacturers recommend a number of basic precautions to help ensure safe operation. First, check the manufacturer's instructions for proper installation. Second, make sure the pump is installed correctly and securely. Third, inspect the pump regularly for any leaks, cracks, and worn parts. Fourth, test the system before starting work. Fifth, turn off the power supply before opening the cover of the unit, and check the fuse box if using an electric motor. Sixth, clean debris away from the intake port and clear clogs from the filter. Seventh, clean any dirt or grease from the bearings, gears, or shafts, and lubricate them if necessary. Eighth, be careful not to overload the pump if using either a propeller or impellers with restricted inlet openings. Ninth, avoid sharp objects near the intake outlet or discharge end of the pump. Tenth, keep children away from the machinery. Eleventh, maintain records of inspections and repairs, and obtain regular maintenance service from qualified personnel. Last, follow safety procedures when working in the vicinity of fire hydrants or sprinkler systems.
Characteristics of Fire Pumps
Firefighting pumps are designed to deliver pressurised water under high pressure to the interior of a building where it is used to put out fires. As fire-fighting is a critical safety issue for buildings of any kind, their design should address many issues at once while being safe enough to use. These characteristics include:
• Water pressure: Firefighting pump performance is measured by its maximum discharge rate (gpm) and minimum discharge rate (cubic feet per minute). The higher the gpm and the lower the c.f.m., the better the pump.
• Weight: Firefighting pumps may weigh hundreds of pounds.
• Size: Firefighting pumps tend to be big, bulky, heavy and require a lot of space — often taking up an entire room.
• Power consumption: Firefighting pumps can consume thousands of watts of power. Many are powered by AC current, though DC models have been developed too.
• Flow capacity: Depending upon the size of the pump, they may be rated to handle flows ranging from 100 gallons per minute (GPM) to 5,000 GPM.
• Noise level: A typical fire station's lobby might be loud enough to cause hearing damage even after wearing earplugs; pumping operations can be deafening.
• Safety features: Firefighting pumps employ a wide variety of safeguards to protect firefighters from injury during operation. An example would be automatic shutoff valves if the pump runs dry, or if the electrical circuit is interrupted. Other examples include emergency stop buttons or manual control handles that allow fire fighters to turn off the pump without having to climb atop the apparatus.
• Reliability: Firefighting pumps will fail due to aging, wear and tear, or maintenance. That means that replacing them periodically is a good idea. Also, a backup system should always be maintained.
Access all the previous parts of this full fire fighting series by clicking the links provided below:
.png)
.png)
.png)
.png&description=Full Fire Fighting & Fire Protection Course - (Part 23)){kind=link}
0 Comments
If you have any doubts, please let me know