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Precautions for using dry screw vacuum pumps

1、 Characteristics of Dry Screw Vacuum Pump

(1) Due to the use of a variable pitch structure, it can save 30% energy consumption and lower exhaust temperature compared to an equal pitch screw;

(2) The gas being pumped has a short distance in the pump chamber and is quickly discharged;

(3) The pumped gas is rarely stirred in the pump chamber;

(4) Small particles are not easy to accumulate;

(5) Can carry liquids, condensable substances, and small particles;

(6) Low vibration and low noise;

(7) The remaining material in the pump chamber is easily removed;


2、 Precautions for use

Precautions for using dry screw vacuum pumps

(1) Back pressure of screw vacuum pump

The usual exhaust pressure for screw vacuum pumps is atmospheric pressure, and the maximum allowable back pressure is 0.3 barg when the motor power remains constant. If the screw vacuum pump operates under high back pressure, it will cause problems such as decreased pumping speed, deterioration of ultimate vacuum, and high exhaust temperature.

(2) Intake temperature

The inlet temperature of the screw vacuum pump is 15 ℃~60 ℃, and the pump can operate continuously for a long time within this temperature range; If the intake temperature exceeds this range, necessary measures need to be taken.

(3) Cooling water temperature

The maximum allowable temperature for cooling water is 32 ℃, and the cooling water flow rate must be appropriately increased.

(4) Ability to handle liquids and solids

The extracted gas of the screw vacuum pump can carry a certain amount of liquid and small particles.


3、 Operation method of dry screw vacuum pump

Operation method of dry screw vacuum pump

1. Inspection and preparation before startup

① Check if all components of the vacuum pump are complete;

② Check the oil level at different oil level mirrors and confirm that the oil level is about 3mm above the centerline of the oil level mirror;

③ Check and confirm the status of each valve in the vacuum unit;

a. Process inlet valve closed

b. Is the inlet filter drain valve closed?

c. The outlet pipeline is unobstructed, and the discharge valve of the outlet pipeline is open

d. Cooling water inlet and outlet pipeline valves open

e. The nitrogen line valve is opened, the purge gas pressure is 0.5 bar, the nitrogen seal gas pressure is 3 bar, and the purge valve is closed

2. Startup operation steps of dry screw vacuum pump

a. Contact the central control on site to confirm that it can be started. Start the vacuum pump through the on-site operation column start button;

b. Close the outlet pipe drain valve;

c. Check or adjust the nitrogen sealing gas flow rate, and confirm that the flow rate is between 2.5-3L/min;

d. Open the blowing valve, confirm that the flow rate of the flowmeter is set to maximum, blow for 5-10 minutes, and then close the blowing valve;

e. Open the process inlet valve and enter the system;

f. During the operation of the vacuum pump, pay attention to observing the temperature of the body. The temperature can be controlled by adjusting the water volume through the temperature regulating valve (the water volume is maximum when the temperature regulating valve is on the 0 scale, and minimum when it is on the 5 scale). The temperature should be controlled as much as possible between 50-75 ℃ to ensure that it does not exceed 80 ℃.

3. Shutdown operation steps of screw vacuum pump

a. Close the process inlet valve and cut out the system;

b. Open the blowing valve, blow for 20-40 minutes, then close the blowing valve;

c. Stop the machine by pressing the stop button on the on-site operation column;

e. Close the nitrogen valve;

f. Close the cooling water valve; If not used for a long time in winter, it is necessary to drain the cooling water inside the body and pipelines to prevent freezing;

g. Open the outlet pipe drain valve and the inlet filter drain valve to check for condensation.

4、 Common faults and treatment methods of dry screw vacuum pumps

Fault of dry screw vacuum pump



5、 Installation precautions for dry screw vacuum pump

Installation precautions for dry screw vacuum pump

1) Before the initial start-up of the screw pump, the mud collection tank, inlet pipeline, etc. should be cleaned to prevent stones, cement blocks, and other metal objects falling during construction from entering the crusher or pump.

Before starting normally, the inlet and outlet valves should be opened and the pipeline should be confirmed to be unobstructed before starting. During the inspection of the running pump, the main attention should be paid to whether the bolts are loose, whether the vibration of the pump and pipeline exceeds the standard, whether the dripping of the filling part is within the normal range, whether the temperature of the bearings and reducer is too high, and whether there are abnormal noises in various operating parts.

2) As a screw pump, the medium it transports also plays a role in cooling and lubricating the rotor in the pump, so it is not allowed to idle, otherwise it will damage the stator and rotor due to friction and heat.

Before the initial use of the pump, fluid medium or lubricant, such as aqueous solution of glycerol or diluted water glass, detergent, etc., should be injected into the suction end of the pump to prevent the pump from being in a frictional state during initial start-up.

In the sewage treatment industry, sometimes large impurities (such as packaging bags) in sludge or scum can block the suction pipeline. These phenomena should be avoided. If such situations occur accidentally, the pump should be stopped immediately for cleaning to protect the safe operation of the pump.

3) The accuracy of the axial alignment of the pump and motor installation is the primary condition for the balanced operation of the pump.

Although pumps are precisely calibrated before leaving the factory, improper installation and fixation of the base can cause distortion of the base, resulting in out of tolerance coaxiality. Therefore, its coaxiality should be verified before the first operation or after major repairs.

4) The loosening of the base bolts and the bolts on various parts of the pump during operation can cause vibration of the body, pump movement, pipeline rupture, and other phenomena. Therefore, it is necessary to tighten the base bolts regularly. The same applies to the bolts on various parts of the pump body. During work, it is necessary to regularly check whether the bolts between the motor and the reducer, between the reducer and the suction chamber, and between the suction chamber and the stator are firm.

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