What Is Back Pressure?

Back pressure refers to the back-end pressure, and is usually used to describe the pressure that the fluid discharged by the system receives at the outlet or the secondary side in the opposite direction of the flow direction (greater than the local atmospheric pressure).

Back pressure

Back pressure refers to the back-end pressure, and is usually used to describe the pressure that the fluid discharged by the system receives at the outlet or the secondary side in the opposite direction of the flow direction (greater than the local atmospheric pressure).

First, usually refers to the pressure that is opposite to the direction of movement when a moving fluid flows in a closed container along its path (such as a pipe or a wind path) due to obstacles or sharp turns. Second, usually used to describe the pressure of the fluid discharged from the system at the outlet or the secondary side (greater than the local

Usually refers to the pressure that is opposite to the direction of movement when the moving fluid flows in a closed container along its path (such as a pipe or a wind path) due to obstacles or sharp turns.

Back pressure related to thermal system

At a certain point in the thermal system, the pressure after the point is the back pressure before the point.

The back pressure of the back pressure unit is the absolute pressure of the steam exhaust of the steam turbine. The difference between the back pressure unit and the pure condensing unit is whether there is a condenser or not. The exhaust of the back pressure unit is recovered after entering the heat exchanger to release heat.

The steam that has been used for work in the steam turbine is discharged above atmospheric pressure, and the exhaust steam is used by other heat users such as industry or heating. This steam turbine is called a back pressure steam turbine.

Hydraulic-related back pressure

It is the pressure in the hydraulic device due to the change of the downstream resistance or the impedance ratio of the component inlet and outlet.

Compressor related back pressure

Back pressure usually refers to the return pressure of the compressor. Sometimes a compressor has to bear several different storage temperatures. The high-temperature storage evaporation temperature is high, and the low-temperature storage evaporation temperature is low. The compressor works according to the low-temperature storage. Evaporation pressure, so the suction pressure is low. At this time, a back pressure valve must be installed on the evaporator outlet pipe to maintain a high evaporation temperature, so that the pressure in front of the valve is kept within a given range, and throttled by the valve. The rear pressure and the suction pressure are equal, so that each evaporator of the system is operated under its own working conditions, that is, the high back pressure is changed to a low back pressure. This is called back pressure regulation.

Back pressure related to the internal combustion engine

Exhaust back pressure is the resistance pressure of exhaust

Large back pressure increases exhaust resistance and reduces engine power

Low back pressure reduces exhaust resistance and increases engine power

Back pressure related to injection molding

During the plastic melting and plasticizing process, the molten material is continuously moved to the front end of the barrel (metering room), and more and more, gradually forming a pressure to push the screw backward. In order to prevent the screw from retreating too fast and to ensure that the melt is evenly compacted, it is necessary to provide the screw with a pressure in the opposite direction. The pressure that prevents the screw from backing is called back pressure. Back pressure is also known as plasticizing pressure, and its control is achieved by adjusting the oil return throttle of the injection cylinder. The back of the injection cylinder of the preplasticized screw injection molding machine is equipped with a back pressure valve, which adjusts the speed of the injection cylinder to drain when the screw rotates and retracts, so that the cylinder maintains a certain pressure; the screw backward speed (resistance) of the full electric motor is controlled by AC servo Valve controlled.

Turbine-related back pressure

Back pressure is actually called the exhaust pressure at the exit of the turbine. It means that the steam after the work is completed has a certain pressure. In the power plant, the steam is converted into water by the condenser to be replenished to the boiler. In other factories and mines, it is to be sent to other departments for production steam, and the baths in life. For water, it is necessary to ensure a certain pressure and temperature. Generally, the back pressure is between 0.5 MPa and 1 MPa. The temperature is more than 200 degrees and does not return to the boiler.