The filling principle of the high tank is to use the constant pressure generated by the constant liquid level relative to the outlet position of the filling tube. When the pressure is constant, the liquid flow rate at the outlet of the filling tube is constant. As the cross section area of the pipeline is constant, the amount of liquid flowing out of the filling tube is also relatively constant per unit time. In view of this situation, it can be seen that the three factors determining the filling accuracy are "flow rate, time and area of tube section". The filling process is shown in the figure.
From the three factors, mechanical structure and electrical configuration of the equipment, it can be seen that the main factors affecting the filling accuracy are as follows:
A) High level tank: if the high-level tank cannot control the dynamic stability of liquid level, resulting in the fluctuation of liquid level, the flow rate will be affected, so that the filling accuracy will change. At the same time, when external pipes are used to provide liquid to the high-level tank, the pressure in the external pipes should be stable. If the pressure in the external pipe is unstable, the liquid level in the high tank will fluctuate greatly, resulting in the deviation of filling accuracy.
B) Diaphragm valve: As the main components of flow regulation, if the diaphragm valve throttle mouth is stable, no change after adjustment, so the amount of outflow is stable, but is actually produce fluctuations, practice has proved that the diaphragm valve will be
affected by the mechanical vibration, fluid flow, the clearance between the adjusting lever and even diaphragm, adjust the clearance between the rod and the fixed seat and other factors, the throttling orifice flow fluctuations, Thus affecting the filling accuracy.
C) Filling tube: For filling tube, practice has proved that if the diameter of the tube is too large and the filling amount is small, the precision will be greatly reduced. If the diameter of the tube is too small, according to the analysis of the above three elements, we can judge that it will take longer to adjust the flow of the equipment, resulting in a great waste.
3. Suggestion
A) The inlet of the high tank shall be able to withstand a pressure of 0.3 Mpa. That is, the buoyancy generated by floating ball in the tank should be able to overcome the pressure of 0.3Mpa in the pipe outside the tank, so that the feed spool is in a closed state. In actual production, it is suggested to keep 0.1Mpa-0.15Mpa-as far as possible to make the valve plate more rigid, so that it can reduce the changes caused by mechanical vibration and liquid flow.
B) If there are many equipment, the automatic back pressure valve can be connected in the circuit to ensure the stability of liquid supply pipeline pressure.
4. To summarize
It can be seen that the main factors affecting the filling accuracy of the high tank are the dynamic stability of the liquid level of the high tank, the mechanical vibration and clearance of the diaphragm valve, and the diameter of the filling tube. The most important factor is the dynamic stability of liquid level in high tank.
