Handling high volume of viscous liquid at medium pressure is a challenge & calls for expertise. We at DEL have aquired this over last 25 years through in house research & development based on customer feed back & field trials.

The proven range of rotary twin gear pump type 'RDRN' have been modified to achieve high pressure by reducing the bearing span, balancing the hydraulic force & blocking the slippage path but without compromising on the basic features prominent with all ROTODEL rotary pumps viz the compactness, efficiency, reliability & low noise level.

A pair of impeller with herringbone gear fitted on hardened & ground shaft with shaft sleeves in floating design supported on either side on needle/bush bearings located on end covers with ltb. wearing plate packed in between and placed inside close tolerance accurately machined casing with built in pressure relief valve makes the pump. Size 1/2" to 2 1/2" are provided with BSP thread inlet - oulet flange connections & they are available with foot or flange mounting. Size 3" to 6" are foot mounted with inlet-outlet port drilled to ASA-300 class. Type RDBX is a bush bearing version & is offered upto 2 1/2" size.

This pump can also be offered with different MOC viz. CI,CS, Bronze, SS etc. Pump upto 35 bar are also offered in this series by further reducing the bearing span. The flange type pump coupled with flange type electric motor is offered in horizontal as well as vertical construction.

 

Pump Operation & Performance Characteristics

Gear pump is the most versatile rotary positive displacement pump & it scores over other types of Pd pumps viz. Screw, Vane, Lobe, Tracoidal, Radial piston etc. & therefore it is used for the widest range of application i.e. loading-unloading, transfer, fuel pressurizing, hydraulic, lubrication in IC engines, Polymers metering applications etc. Gear pump can develop high pressure uo tp 210 bar in same configuration simply by tightening the working clearances & improving the workmanship, whereas in screw pump the thread length is needed to increase making the pump bulky & difficult to manufacture. In gear pump each tooth gap contributes to the capacity while in screw pump only one pitch length contributes to the capacity thus gear pumps are always cpmpact & efficient. The capacity of the pump varies directly with speed but remain constant against pressure, however some liquid always by-passes to suction due to running clearance between the casing & impeller causing slip which depends upon the differential pressure, viscosity of the liquid & the workmanship. Gear pumps are capable of handling liquids of any viscosity, th slip reduces with increse in viscocity but the frictional power increses. Though the pump has a self priming capability some net positive suction head(NPSH) is always required to avoid cavitation, this again depends on the viscosity of the liquid to be pumped & the pumping speed.

Internal power losses

In rotary gear pumps are of two types.The mechanical loss is the power required to overcome friction drag of all the moving part within the pump while viscous loss is power loss due to fluid viscous drag & shearing action of the fluid, this can be calculated from the graph shown here.

Horse power calculation

The bhp required to drive a rotary pump is sum of the theoretical HP & internal losses. The former is the actual work done in moving the fluid from inlet pressure condition to outlet pressure condition & is product of constant C=0.037, Capacity in M3/hr. & Pressure in Kg/CM2 or Constant c-2.3, Capacity in GPM & Pressure in PSI.

Gear Pump Selection & uses

RDBX/NX series pump are medium pressure pumps designed for viscous pressure application up to 21 bar. The bush bearing version type RDBX is used for clean or dirty viscous & semi viscous liquid where the shaft surface speed is less. Pump upto 2^1/2" size can be run at 1440 RPM & for higher size the speed should be reduced to 960 RPM or lower. The self-lubricated needle roller bearing type can be used for clear viscous liquid & can be run at 1440 RPM for all the sizes. This pump are ideally suited for fuel pressuring, hydraulic, medium pressure lubrication & transfer applications.

Inspection & testing

All pumps are assembled after due inspection of each & every parts & than they are tested for duty parameters in accordance with API-676 & JIS-B 8312-1976. Third party inspection are also offered, we are approved by following consultants & inspection agencies.