Application of vacuum self - priming pump theory analysis

The vacuum self-priming pump operates by creating negative pressure to initiate the pumping process. Before starting the pump, the vacuum pump must be activated first to evacuate air from the suction pipe and fill it with water, ensuring the pump begins smoothly. Once primed, the pump can be started by closing the valve first to avoid any surge in pressure. To ensure the pump functions correctly, two vacuum pumps with varying exhaust volumes (ranging from 2m³/min to -10m³/min depending on the pipeline length) are recommended. These pumps provide a vacuum degree of 0 to 200hPa. For the vacuum self-priming pump group, both the pump and its piping system can be centrally controlled from the pump station operator's station or operated locally. The pump system includes an automatic interlock mechanism where if one pump fails, the backup pump automatically starts. Similarly, the vacuum pump and water pump are programmed to start automatically following a specific sequence, and they stop when the electric butterfly valve at the pump outlet fully closes. The pump is horizontally arranged, with the pump and motor mounted on the same base. The performance of the pump under design conditions must ensure that flow, lift, and efficiency do not deviate negatively. The positive deviation of the head should not exceed 5%. The lift-flow curve should gradually rise from the design flow to zero flow, considering the motor speed could vary by up to 20%. At the pump's rated operating condition, the efficiency should be optimal. The pump must withstand reverse speeds of up to 120% of its rated speed without damage, but should not start if reversing exceeds 20% of the rated speed. The pump's Q-H curve must be smooth from the design point to the shut-off head, which should exceed the design point head. The curve must meet the system's resistance requirements at all times. The pump should generate forces and moments horizontally, vertically, and under torque, including during closed and reversed conditions, accounting for seismic activity and temperature changes. It must handle these forces effectively and pass them to the pump base. The pump requires no pre-lubrication or external water supply for lubrication. After starting, the pump extracts water from the outlet pipe, filters it, and uses it to lubricate/cool the bearing and shaft seal assembly. The pump seal employs a mechanical seal. During normal operation, the pump should exhibit excellent cavitation performance, preventing cavitation and vibration. The pump materials include a cast iron body, high-quality SKF bearings, wear-resistant 304 stainless steel impellers, and other components selected based on standard materials. An automatic exhaust valve is included in the pump housing. The pump connects to the motor via a rigid coupling, which features a detachable and solid protective cover. The pump needs to operate efficiently in the high-efficiency area even at NPSH = 5m. For the motor, it is a three-phase asynchronous motor with a protection class of IP54, using self-cooling. The motor must start at 85-100% of the rated voltage and power, accelerating the startup process. The motor's noise level at 1.0m height and 1.2m distance from the pump casing should not exceed 85dB(A). The maximum vibration amplitude of the dual-pump system should adhere to relevant standards. The motor insulation class should be F, with a junction box protection class of at least IP55. The motor should withstand all thermal and mechanical stresses at the design ambient temperature and handle vibrations consistently.

Smart Glass

Smart Glass,Architecture Glass,Switchable Privacy Glass,Smart Automobile Glass

Shenzhen Filmbase Technology Co., Ltd. , https://www.globalfilmbase.com