Product Detail

Positive Displacement Pumps

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A Positive Displacement (PD) Pump moves fluid by trapping a fixed volume and then forcing (displacing) that volume into the discharge pipe. Unlike centrifugal pumps, PD pumps deliver a constant flow rate regardless of pressure, making them ideal for high-viscosity fluids and precise dosing applications.

  • Gear Pumps – Used for oil, fuel, and chemical transfer.
  • Diaphragm Pumps – Excellent for handling aggressive and viscous fluids.
  • Rotary Lobe Pumps – Hygienic design suitable for food, beverage, and pharmaceutical industries.
  • Peristaltic Pumps – Perfect for chemical dosing and slurry handling.
  • Progressive Cavity Pumps – Ideal for handling sludge, pastes, and thick fluids.

Description

🔧 Working Principle:

  • Fluid enters a chamber or cavity.

  • A mechanical component (gear, piston, diaphragm, rotor, etc.) displaces the fluid.

  • The fluid is pushed through the discharge at a consistent rate.


🔧 Key Components :

Component Function
Pump Casing Encloses all internal parts; contains and directs fluid flow.
Inlet & Outlet Ports Allow fluid to enter (suction) and exit (discharge) the pump.
Displacement Element The moving part that displaces fluid (gear, piston, screw, etc.).
Drive Shaft Transmits mechanical energy from motor to the displacement element.
Seals & Gaskets Prevent leaks; important in high-pressure or toxic fluid applications.
Bearings & Bushings Support rotating/moving parts, reduce wear.
Relief Valve Protects pump from overpressure; often internal or external.
Motor or Driver Provides the required mechanical power to operate the pump.

🧪 Typical Applications:

  • Chemical dosing

  • Oil and gas transfer

  • Hydraulic systems

  • Food and beverage processing

  • Pharmaceutical and cosmetic production

  • Sludge, slurry, and viscous fluid pumping


Advantages:

  • Constant flow regardless of discharge pressure

  • Ideal for high-viscosity or shear-sensitive fluids

  • Can handle solids and slurries

  • Excellent for metering and dosing

  • Self-priming and can run dry (certain types)


Disadvantages:

    • Typically lower flow rates compared to centrifugal pumps

    • May pulsate unless dampened

    • Can be damaged by running against closed valves (need relief valves)

    • More moving parts = potentially higher maintenance

       Technical Details

      📐 1. Key Specifications:

      Parameter Typical Range / Description
      Flow Rate (Q) 0.1 LPM to 100,000+ LPM (depends on type & size)
      Pressure Range Up to 1000+ bar (especially for piston or plunger types)
      Viscosity Handling Up to 1,000,000 cP (ideal for thick, viscous fluids)
      Speed (RPM) 10 – 1800 RPM (varies by application)
      Temperature Range -50°C to 350°C (with special materials)
      Self-Priming Ability Yes (most PD pumps are self-priming)
      Solids Handling Capable (especially peristaltic, lobe, or screw pumps)

      ⚙️ 2. Components Vary by Type:

      • Rotary PD Pumps: Use gears, screws, vanes, or lobes.

      • Reciprocating PD Pumps: Use pistons, plungers, or diaphragms.

      • Include chambers, seals, relief valves, and drive systems.


      Features of Positive Displacement Pumps

      1. Constant Flow Output

        • Delivers steady volume regardless of pressure changes.

      2. Self-Priming

        • Can start pumping without external priming aid.

      3. Handles High Viscosity & Slurry

        • Ideal for thick fluids, pastes, or those containing solids.

      4. High Pressure Capability

        • Suitable for high-head applications like injection systems.

      5. Precision Metering

        • Offers accurate and repeatable flow, useful for dosing chemicals or pharmaceuticals.

      6. Low Shear

        • Gentle pumping action protects shear-sensitive fluids.

      7. Dry Running (some types)

        • Peristaltic and some diaphragm pumps can run dry without damage.


      Benefits of Positive Displacement Pumps

      Benefit Explanation
      💧 Consistent Flow Ideal for batching, dosing, and precise delivery.
      🛠️ Versatile Handling Works with a wide range of fluids – thin to extremely thick.
      🚫 No Cavitation Risk Performs well at low suction pressures.
      ⚖️ Energy Efficient Especially efficient at low flow, high pressure conditions.
      💡 Flexible Design Can be customized with various drives, materials, and seals.
      🔁 Reversible Operation Many types can run in both directions.

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