Gear pump

Gear Pump (Concentrated Pump)

Gear pumps or condensate pumps from types of pumps are positive displacement Fluid movement in the gear pump is done by rotating the gears. These pumps are among the types of Self Prime pumps or self-suction pumps because they have a very high suction power and at the same time have the ability to pump liquids with high, medium and low viscosity. Gear pumps are available in two types: internal gear pumps and external gear pumps.

External gear pump (external gear) :

In external gear pumps, the flow rate can be adjusted according to their circumference and internal structure, so for pumping the exact amount of fluids such as acids and bases and Chemical additives as well as fuels and polymers, and are used in machinery as a hydraulic and power transmission system. These pumps are very popular due to their long life as well as covering a wide range of fluids and reasonable prices.

Large size works at 650 rpm and small size at 1450 or 3000 rpm.

Application of external gear pump

• For pumping edible oils
• Food pumping
• Pumping lubricants
• etc

External gear pump material

• Gear and body material: cast iron, bronze, polymer and stainless steel.
• Shaft material: aluminum, ceramic, alloy steel, steel
• Bush material: silicon carbide steel, bronze, carbon
• Sealing type: mechanical seal (single and double), magnetic, lip seal, Peking

Advantages of external gear pump

• High fluid coverage
• Using this pump instead of dosing pump, due to high efficiency and accuracy
• Can be added to that heating and cooling jacket
• Various materials
• Simple and easy maintenance
• Communication and coordination with all types of connections, both input and output connections
• Quiet and quiet
• Lack of sensitivity to dust
• High speed and pressure

Disadvantages of external gear pump

• In the bushing type, the bearings are located inside the fluid.
• Solid particles inside the fluid cause corrosion and wear of the gear.

Internal gear pump (internal gear) :

The internal gear pump is suction and can be rotated in both directions, which means that it can be used for both filling and emptying. . The internal gear pump is suitable both for pumping dilute fluids such as solvents and oils, etc. and for pumping concentrated fluids such as asphalt and adhesives.

Internal gear pumps can also be used to pump a variety of oils, hot oils, fuels, resins, polymeric materials, alcohols and solvents, asphalt and bitumen. He mentioned polyurethane foam, foods such as peanut butter, dyes, chocolate inks, soaps and pigments.

Use of internal gear pump

• Pumping food
• Pumping lubricants
• Pumping all kinds of edible oils
• Pumping all kinds of edible oils
• Fuel pumping
• Resin pumping, polymer

Internal gear pump material

• Body and gear material: alloy steel, cast iron, stainless steel, bronze, polymer (Teflon)
• Bush material: carbon graphite, Silicon Carbide , Ceramic, Bronze, Tungsten Carbide
• Shaft material: stainless steel, alloy steel
• Sealing material: mechanical seal (single and double), cartridge, magnetic, packing

Advantages of internal gear pump

• Suicide
• Pumping a wide range of viscosities
• Body material varies depending on the application
• Smooth and pulse-free current
• Ability to dry (in a short time)
• Ability to rotate in two directions (filling and emptying a tank)
• Suitable for high viscosity fluids
• Very low NPSH (thus reducing the probability of cavitation)
• Easy maintenance
• Coordinate with a variety of connections at both the input and output, such as flanges and threads

Disadvantages of internal gear pump

• Its operating speed and pressure are low

Gear Pump Design

Gear pumps are designed in such a way that the gears are located inside the shell, one of the gears is connected to the electric motor, which is called the drive gear. The other is the movable gear, which is located under the drive gear and causes rotational rotation inside the housing. The fluid in the chamber engages and is directed to the pump outlet.

The gearbox is used when the speed is below 700 rpm. Gear pumps are used for viscous fluids that have a low rotation rate and also for dilute fluids that have a higher rotation rate. For example, for liquids that have a very high viscosity, such as heavy liquids, pastes and oils, a speed of 200-500 rpm is used.

In outlet gear pumps, the pipe is designed first horizontally and then vertically. The shell of gear pumps is made of cast iron, its gear is plated steel and the axis of this pump is made of steel.

Fluid displacement is actually the volume of fluid that travels through the space between the gears. The amount of this displacement is different at different times and therefore the amount of displacement per rotation can not be accurately calculated. But it can be calculated and expressed approximately. For example, if the area of ​​the space between the teeth is assumed to be equal to the area of ​​the teeth themselves, then the displaced volume per rotation of the axis is equal to the volume occupied by half the area between the gear heads.

Gear head: The part of the gear that is after the step circle and is called the height of the gear head, and the base diameter is multiplied by 2 and multiplied by the width of the gear.

In the above relation, it is sufficient to divide the flow rate by 231. Which becomes the following relation: