Internal Eccentric Gear Pump

A Comprehensive Guide to Positive Displacement Pumps

Blog / 2024

Internal Eccentric Gear Pump

Our Internal Eccentric Gear Pump is a reliable and efficient solution based on the simple “gear within gear” principle. The rotary and idler gears in the pump head create cavities between their teeth, achieving positive displacement. This ATEX-available pump, capable of pumping fluids too viscous for a Centrifugal Pump, features only 2 moving components within the process medium. The Internal Eccentric Gear Pump delivers efficient suction lift capabilities and bi-directional flow, ensuring smooth and accurate performance for various applications.

Typical applications for our Internal Eccentric Gear Pump:

Fuel Oil, Gas Oil, Diesel-Fuel
Hot Oil Circulations
Pharmaceutical
Detergent
Dye
Asphalt
Food Industry

Brochure

Overview Features & Benefits Specifications

The simple “gear within gear” principle of Internal Eccentric Gear Pumps means that there are only two moving components within the process medium. The positive displacement is achieved by the filling of the cavities between the teeth of both the rotary and idler gears located in the pump head. With each revolution, a fixed volume of fluid enters the casing through the suction port, filling the space between the teeth of the gears. The crescent within the pump head then separates the fluid as the idler gear turns on the pump shaft.

Image 1: Fluid entering the pump

The orange-coloured section in the image represents the process medium as it is entering the pump suction port and the pump casing & filling the cavities between the Idler Gear (Red) & Rotary Gear (Brown). The three arrows indicate the direction of fluid passage through the pump and the rotational direction of the gears.

Image 2: Fluid filling the cavities & split of flow

As the fluid progresses through the pump head and fills the cavities between the gears, it is also separated by the crescent shape in the pump head, which acts as a seal preventing backflow between the suction & discharge ports.

Image 3: Pump almost flooded

As the fluid fully fills the casing, all cavities between the gears are completely filled in the form of locked pockets of fluid to guarantee absolute volume control and enable the pump to deliver a fixed volume per revolution.

Image 4: The pump is flooded & starts to discharge the process medium under pressure

Once the pump is fully flooded, the rotor and idler gears mesh together and form a liquid seal which is equidistant between the pump ports, which then enables the fluid to exit the discharge of the pump under pressure. The delivery pressure is dependent on the installed power of the motor.

Operating Principle of Yildiz Eccentric Gear Pump

Overview

Image 1: Fluid entering the pump

Image 2: Fluid filling the cavities & split of flow

Image 3: Pump almost flooded

Image 4: The pump is flooded & starts to discharge the process medium under pressure

Operating Principle of Yildiz Eccentric Gear Pump

Features & Benefits

Accurate and pulseless flow at high differential pressures
Ability to pump fluids too viscous for Centrifugal Pumps (higher differential pressures than Centrifugal Pumps)
High mechanical efficiency across different pressures and varying flow
Efficient suction lift applications
Ability to operate at different points on their curves as flow is proportional to rotational speed
and pressure is dependent on the installed motor power
Bi- Directional flow
ATEX-available for use in hazardous environments

Specifications

Max Capacity (m³/hr)	200m³/hr
Max Pressure (Bar)	15 Bar
Viscosity (cSt)	up to 55,000 cSt
Max Speed (rpm)	1400 rpm
Max Temperature (°C)	200°C
Materials & Limits
Connection Sizes	3/8″ – 8″
Capacity Range	0.1 – 250m³/hr
Pressure Range	1 – 15 Bar
Temperature Range	up to 200ºC
Speed Range	20 – 1720 rpm
Viscosity Range	20 – 5,500 cSt
Pump Body & Cover	Cast Iron, Spheroidal Cast Iron, Cast Steel, Stainless Steel AISI 304/316
Gears	Spheroidal Cast Iron, Cast Steel, Stainless Steel AISI 304/316, CrNi Stainless Steel
Bearings	SnBz12 Bronze, Carbon Graphite, Silicon Carbide, Hard Metal Coated Steel
Sealing	Soft Seal / Packed Gland, Rotatherm Seal, Lip Seal, Mechanical Seal, Cartridge Type Mechanical Seal

Sizes Available:

Model	Max Capacity (m³/hr)	Max Pressure (Bar)	Viscosity Range (cSt)	Max Speed (rpm)	Max temperature (°C)
Bareshaft units with In-Line Connections for Low Flow & Low Viscosity Fluids & High Pressures
YMK ¾	0,4	15	10 – 1650	1400	100
YMK ½	0.8	15	10 – 1650	1400	100
YMK 1	2	10	10 – 1650	1400	120
YMK 1½	5.7	12	10 – 1650	1400	200
YMKU 1½	6.7	12	10 – 1650	1400	200
YMK 2	9	12	10 – 1650	1400	200
Bareshaft Units with 90º Connections for Higher Viscosity Fluids & Medium Pressures
YP 1	3	7	10 – 55000	1400	100
YP 1½	5.5	7	10 – 55000	1400	100
Heavy Duty Bareshaft Units for Higher Viscosity Fluids, Flows & Pressures
YK 1	3	14	10 – 55000	1400	200
YK 1½	6	14	10 – 55000	1400	200
YKU 1½	7	14	10 – 55000	1400	200
YKF 20 0	15	14	10 – 55000	900	200
YKKF 2	11.6	14	10 – 55000	500	200
YKF 2	15	14	10 – 55000	500	200
YKF 2½	25.5	14	10 – 55000	500	200
YKUF 2½	32	14	10 – 55000	420	200
YKF 3	32	14	10 – 55000	420	200
YKBF 3	55	14	10 – 55000	400	200
YKF 4	55	14	10 – 55000	400	200
YKYF 40 0	90	14	10 – 55000	400	200
YKBF 4	120	14	10 – 55000	400	200
YKF 5	110	9	10 – 55000	280	200
YKF 6	135	9	10 – 55000	350	200
YKF 8	200	9	10 – 55000	220	200
Close Coupled Units for Low to Medium Viscosity Fluids & Pressures
YMB 1	3	10	10 – 1650	1400	70
YMB 1½	5.7	10	10 – 1650	1400	70
YMBF 2	15	5	10 – 5500	500	70
YMBF 2½	23	5	10 – 5500	450	70
YMBUF 2½	32	5	10 – 5500	400	70
YMBF 3	32	5	10 – 5500	400	70