Sewage suction trucks are a type of modern sanitation vehicle mainly usedfor cleaning urban sewers, clearing deposits from pipes, and unclogging sludge in drainage areas. They can also be used for cleaning industrial liquid pipes, walls, and surfaces, and can serve as water-spraying or road-washing vehicles. In emergency situations, they can even be used for firefighting. The main function of the vacuum pump in the sewage suction truck is to create suction for the waste material. The two types of vacuum pumps used in sewage suction trucks are:
1. Water Circulation Vacuum Pump
- Working Principle: The water circulation vacuum pump works by using an impeller installed eccentrically inside the pump body. The pump body contains an appropriate amount of water as the working fluid. As the impeller rotates, the water is thrown outward due to centrifugal force, forming a water ring inside the pump chamber. The pump relies on changes in the volume of the pump chamber to achieve suction, compression, and exhaust, thus enabling the suction and discharge of waste in the sewage truck.
- Drive Mechanism: The water circulation vacuum pump is powered by a high-power generator set that is separately controlled via an electric switch and manually controlled throttle. It shares the chassis fuel tank and comes with an onboard water tank to supply water for the pump during operation.
- Suction Performance: Horizontal suction can reach 20-30 meters, and the vertical suction range is 6-10 meters.
2. Rotary Vane Vacuum Pump
- Working Principle: The rotary vane vacuum pump uses eccentrically rotating blades within a rotor inside the pump chamber. This rotation displaces air, creating a vacuum or negative pressure inside the sealed tank. The pressure difference between the atmospheric pressure and the tank’s internal pressure enables the suction and discharge of waste.
- Drive Mechanism: The rotary vane vacuum pump is driven by a power take-off (PTO) connected to the engine’s gearbox, powered through a driveshaft and controlled via a pneumatic switch. This type of vacuum pump has a simpler structure and does not require the high-power generator set used by water circulation pumps, making it more cost-effective.
- Suction Performance: The vertical suction range is slightly lower than the water circulation pump, at 5-6 meters.
Key Differences
- Cost: Water circulation vacuum pumps tend to be more expensive due to their more complex design and the need for a generator set.
- Efficiency: Water circulation pumps can work for extended periods because the water serves as a coolant, preventing overheating. Rotary vane pumps, however, generate heat from high-speed rotation and usually need to cool down after 2 hours of continuous work.
- Maintenance: Both systems offer self-loading and unloading capabilities, liquid level indicators, and openable rear covers. However, the water circulation pump has an advantage in long-duration tasks, while the rotary vane pump is more suitable for shorter, cost-sensitive applications.
Common Issues and Maintenance
- Water Source Instability: Fluctuations in the water source can cause damage to the pump. For example, a sudden rise in water temperature can lead to cavitation, which is a sign of internal damage to the high-pressure pump.
- Overpressure: Operating the pump at pressures higher than its rated limit can damage it, as exceeding the normal workload will stress the pump beyond its capacity.
- Contamination and Cleaning: Using overly viscous cleaning agents, or failing to install filters in the intake pipe, or having small particles in the valve can damage the high-pressure pump. Regular maintenance and ensuring clean operational conditions are key to preventing pump damage.
