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Product Details

The DP Series Screw Vacuum Pump1.1 General
       This Dry Vacuum pump discharge the inhaled gas under pressure by use of two screw rotors ,having a profile comprising plurality of curves , i.e Archimedean curve , Quimby curve and arc , which rotate smoothly with a certain clearance maintained between each other and inside wall of the casing .
The inhaled gas to be fed under pressure is smoothly pressurized against the pressure gas on the discharge side . The pump is so constructed as to allow no oil to be mixed in the discharge  gas.The power of motor is transmitted to the main rotor shaft through a V - Pulley or a coupling device , and further to the driven rotor shaft through a timing gear.
1.2 Construction
   1.2.1 Screw  shaft
       The screw shaft is made of high grade spheroidal graphite cast steel, and precision machined through numerical control by a special machine. It has a perfect dynamic balance testing after the Screw is machined.
   1.2.2 Timing Gear
       The timing gear is the most important part of the screw vacuum pump , and it is necessary for turning the rotor with a certain clearance kept from each other.The tooth surface is heat cured , and then polished with a special high precision tooth polishing machine for lowering of noise .
   1.2.3 Bearing
       The bearing on fixed side is a angular contact ball bearing and that on expansion side is a roller bearing of heavy load capacity. These bearings have been selected as to stand high speed and heavy load service and to assure the accurate keeping of the clearances between gears and between Screws.
   1.2.4 Shaft seal
       The shaft seals are consist of Double Lip Seals on Suction side and Bellow type Mech .Seal on Discharge side. These Seals prevent oil from Front End Plate to inside of Casing . Front End Cover side of drive shaft is sealed by an Oil seal.
   1.2.5 Oil Level Gauge
       Oil Level Gauge is located at Front End Cover .Oil should be supplied to the top level of Red mark. If the oil level is too low , Gear,  Bearing and Mechanical seal will be damaged as a  result of improper lubrication , So , when pump is not in use , be sure to check the oil level and contamination , and then , refill or change the oil when needed , The oil is splashed over by rotation of timing gear and lubricate bearings and Mechanical seals .
1.3 Specification
   1.3.1 DP 一4 technical parameters：

Note
       ( 1) Above listed amount of oil is only for reference , and surplus be available. It should be noted that  fluorine and mineral type of oil are available . For Shipping , We supply pure gear oil.
       ( 2 ) Above listed amount of Cooling Water is based on water temperature 20℃ .So the amount of water be vary when using After Cooler.
Please check with Vendor's approved drawing.
1.4 Piping Diagram

1.5 Purges
   Cooling Purge
       This purge is intended to cool the Screws and inside the casing. During the operation of the pump , this purge is required to cool down compression heat of discharged process gases . The process gases introduced into the casing from the suction side are compressed by the rotation of the screw and transferred to discharge side , This process gases are heated by compression  heat .Since this compression heat reaches above 130 ℃ -200 ℃ in discharge side , we need cooling purge to cool down this heat . In most case ,we use atmosphere in cooling purge and it is our standard purge . We provide an air filter near the discharge side of casing for this purge .
       (1) Purges amount

       (2)Type of Cooling Purge
       ① Standard： Atmosphere purge through air filter
       ② Using Heat Exchanger : Recycle process process  gases after cooled through the heat exchanger .
       ③ Using Inert gases like N2 and etc . instead of atmosphere or cooled process gas .
   Sealing purge
       This purge is required during the operation and intended to pressurize the front end cover with Inert gas like N2 so that the process gas or fluid can not enter into the timing gear set and bearings. You can use either one of Two plugs provided on the top of Front End Cover for this sealing purge connection.
The purge pressure is below 0.5Kg/cm²G and the leak rate for our Mech.seal is below 3cc/hr.Also our Mech.seal can seal pressure up to 3Kg/ cm²G.
   Cleaning purge
       This purge is required to clean inside the pump before stopping the pump. Before stop the pump, purge N2 gas, steam or cleaning agent for 20 to 30 minutes after closing the main valve on suction side to clean sticky process materials or process gases. This purge is especially important  when pumping corrosive/toxic gases or sticky materials like resin and etc.
   Pump Steam Flushing
       After each process, run the pump for 10 -20minutes without load after close main suction V / V ( Dry run,Cleaning purge ) . This is to remove & dean process gases / condensed vapors from the pump which are build up inside the pump during the process. These process materials build up inside the pump can be reason of pump overload when restart the pump for next process.
Also, when restart the pump after a certain period later, these process materials can cause pump seizure or overload on the pump.
In this case, flush steam inside the pump & Screws with following procedure instead of rotating the pump with force.
   steam Flushing Methode(after pump operation)
       (1) process materials that require Steam flushing :Oligomer Monomer polymer Resin etc.
       (2) steam pressure :approx.1Kg/ cm²G.
       (3) Flushing procedure
       1. Close suction V/V open discharge V/V or silencer / separator ^,s Drain V/V
       2. Inject Steam for 1∽10 minutes(the injecting time varies with process material)through pump suction line or through a plug in suction flange
       3. Try to rotate shaft(Pully or Coupling) with hand to see whether the pump rotate smoothly or not(This time be careful not to start the motor)
       4. If the pump move smoothly stop injecting steam.
       Then start motor and check the pump run normal or not.
       (4) If not satisfied with above procedures repeat the procedures 2∽3 times more.