Español
Pусский
The most important mode of operation in the auxiliary facilities of mechanical seals is flushing. Then how to control the amount of flushing?
The amount of flushing can be changed with a throttle valve or controlled with a restricting orifice plate. Since the throttle valve has no concept of quantity, most of them now are replaced by restricting orifice plates. The diameter of the orifice plate can de determined according to the required flushing volume and the pressure difference between the front and back of the orifice plate. In other words, after the aperture/core diameter is determined, once the pressure difference between the front and rear of the orifice plate is set , the flushing volume will be determined & cannot be adjusted.
The calculation method can be used to calculate the pore diameter of the orifice plate approximately according to the orifice plate flow formula, but due to the different structure of the orifice plate, the calculation results need to be corrected through experiments. In this case, it is more convenient to directly use the experimental results. Therefore, the amount of flushing is mostly checked with experimental charts.
There are two types of orifice plates currently in use. One is flange-connected and the other is thread-connected. The flange-connected orifice plate has a simple structure and is easy to assemble and disassemble. It is a circular plate with a thickness of 4~6mm & has a "tail" for easy installation, and is stamped with a numerical value of the aperture. Usually it is made of stainless steel. For the orifice plate of this structure, the relationship between flow rate, pore diameter and pressure difference is shown in the table below.
The amount of flushing that does not need to be cooled is not strictly controlled, and the amount of flushing that is used after being cooled is required to be more accurate, which involves the amount of cooling water and the temperature after cooling. If the amount of flushing is small and the diameter of the orifice plate cannot be too small (in that case easy to block), then the method of connecting orifice plates in series can be used. When self-flushing is used, an orifice plate is installed at the outlet of the pump, and another orifice plate is installed after passing through the cooler. The flow through two series-connected orifice plates is about 70% of the flow rate of the case when only one orifice plate is used. See the figure below for the threaded connection orifice. It is equivalent to a nozzle, and the difference with the former is that the orifice plate is longer.
