The variable motion of worm gear is driven by mechanical dosing pump's motor through driect-connection transmission. Then rotational motion is transformed into reciprocal rectilinear motion by crank-link mechanism. The so-called diaphragm metering pump uses a specially designed and processed flexible diaphragm to replace the traditional piston, and realizes reciprocating motion under the action of the driving mechanism, thereby completing the process from suction to discharge. Due to the isolation effect of the diaphragm, the isolation between the metered fluid and the driving lubrication mechanism is truly realized in structure. Since its diaphragm bears the pressure on the medium side, the maximum discharge pressure of a mechanical diaphragm pump generally does not exceed 1.2MPa.


Ⅰ. The working theory and malfunctions of mechanical dosing pump

1. The front and back movements of the diaphragm are used to change the diaphragm and the pump head to cause the ball valve to move up and down to form vacuum adsorption and push to achieve the purpose of liquid transportation.


① When the diaphragm is pulled back, the outlet ball valve falls down and tightly fits the ball seat. The inlet ball valve floats upward due to the vacuum generated between the diaphragm and the pump head when the diaphragm is pulled back, and the liquid is sucked up.


②When the diaphragm is pushed forward, the inlet ball valve is airtight with the ball seat to prevent liquid from passing through, and the outlet is pushed forward by the diaphragm to open the ball valve and the liquid is discharged.


2. Through the above motion principle, it can be simply realized that if there is air leakage caused by any factor of pump head, diaphragm, and ball seat of the metering pump, transporting cannot be completed, or the flow rate is abnormal. The usual reasons of malfunction are:

①the ball seat and ball valve can not be airtight

②the entrance and exit are blocked by foreign matter

③diaphragm damage.


Therefore, when the liquid is conveyed abnormally, the problem should be solved in this direction, and the factors that cause the above situation are too numerous to list, depending on the piping, fittings and operating conditions at the moment.


Ⅱ. Features of mechanical diaphragm metering pump:

(1)Relatively low price;

(2) No dynamic seal and no leakage;

(3) It can transport high-viscosity media, abrasive slurries and hazardous chemicals;

(4) The diaphragm bears high stress and the diaphragm life is relatively low;

(5) The outlet pressure is below 3MPa, and the measurement accuracy is ±2%;

(6) No safety relief device.


Ⅲ. How to install a mechanical diaphragm metering pump?

The mechanical diaphragm metering pump is supported by a solid, anti-vibration foundation. The foundation is higher than the ground, one side of which is washed by water, and is also easy to repair. Enough space around the mechanical diaphragm metering pump is reserved to facilitate pump maintenance and adjustment.


There are mounting holes at the bottom of the mechanical diaphragm metering pump for mounting anchor bolts.


The mechanical diaphragm metering pump installed outdoors should be covered by a canopy.

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