Proven performance & operational economy are the chief consideration while evaluating once pumping requirement. When it comes to handle viscous or semiviscous liquid , ROTODEL rotary gear pump is an obvious choice for these very reasons.
ROTODEL gear & screw-gear type positive displacement rotary pumps are wel accepted & loudly acclaimed industrial pump for it's compactness, efficiency, reliability & silent performance. This pump have out class conventional gear pump & have also broken the myth about screw pumps by offering better efficiency at much reduced cost.
These pump have replaced many imported gear & screw pumps at various installation in steel plants, power plants, refineries,oil installation, navy vessels & ships.
The most popular range of 'RDNXJ' series ROTODEL rotary screw-gear pump have been re-designed & re-engineered to offer further simplicity with added economy & reliability meeting international standard viz. API, JIS, DIN & above all the growing expectation of enlightened customers.
New'RDRN' series pump now offers enlarged capacity range with option of self or independently lubricated, jacketed or non - jacketed construction with pump all in the sizes designed to run at 1500 RPM there by reducing the cost of primeover.
It will be a wise decision to go for 'ROTODEL' rotary pumps for all your new & old installation even if it calls for scrapping the existing one.
Designed low-leakage path improve volumetric efficiency.
Smaller bearing span reduce bending effect.
Simple & sturdily design simplifies maintenance.
PUMP CHARACTERISTIC :
Gear pump is a rotary positive displacement pump with positive pressure characteristic. The capacity of the pump varies directly with speed but remain constant against pressure, however due to running clearance between the casing & impeller some liquid always by-passes to suction causing sleep, which depends upon the differential pressure, viscosity of the liquid & ofcourse the workman-ship. The pump do not develop pressure on it's own but has capacity to over come the back pressure on it way with out substantial drop in capacity. The pump s are capable of handling any viscosity the sleep reduces with viscosity but the viscous power increases. The pump has a self-priming capability but some net positive suction head (NPSH) is always required depending upon the viscosity & pump speed to avoid caviation.
INTERNAL POWER LOSSES :
The internal power losses in rotary pumps are of two types. The mechanical losses is the power necessary to overcome friction drag of all the moving part within the pump. While viscous losses is power lost due to fluid viscous drag & shearing action of the fluid itself, this can be computed from the graph showen here.
H.P. CALCULATION :
The break horse power required to drive a rotary pump is sum of the theoretical HP & internal losses. The theoretical horse power is the actual work done in moving the fluid from inlet pressure condition to out let pressure & is a product of Constar. C = 0.4 designed capacity in M3/HR & discharge pressure in Kg/Cm2.
PUMP SELECTION :
The bush bearing type of pump can be used for clean viscous liquid having sufficient lubricating value for intermitant duty, however for continues duty pump with needle roller bearing in 'RDRN' series may be select. For liquid having low viscosity, poor lubricating values or containing dirts or impurities pump with independently lubricated bearing should be selected. Liquid which tends to solidify at lower temp. the jecketing construction should be selected to facilitate the heating of the pump by steam or thermic fluid etc.