How to choose the appropriate ALP series gear pump according to the working conditions?

Choosing a suitable Marzocchi ALP series gear pump requires comprehensive working condition parameters, media characteristics and installation conditions. The following is a systematic selection guide.：

1. Matching of core parameters
   Pressure demand
   Conventional pressure: ALP1/ALP2 series supports 250-270 bar continuous pressure (peak 290 bar), ALP3/ALP4 series supports 230 bar continuous pressure (peak 270 bar).
   Selection principle: The actual system pressure needs to be ≤the rated pressure of the pump, and the peak pressure ≤ the peak pressure of the pump.For example, the ALP3 series (rated at 230 bar) is optional when the system pressure is 200 bar.
   Flow calculation
   Formula: Flow rate (L/min) = displacement (cm3/rev) × rotation speed (rpm)÷1000.
   Example: When the flow rate is 50 L/min and the speed is 1500 rpm, the displacement needs to be ≥33.3 cm3/rev. ALP3-D-33 (displacement 33 cm3/rev) is optional.
   Speed adaptation
   The ALP1 series has a maximum of 6000 rpm, and the ALP4 series is limited to 2800 rpm.It is necessary to ensure that the drive speed is ≤ the rated speed of the pump.
2. Adaptation of media characteristics
   Corrosive media
   When conveying corrosive liquids such as acids and alkalis, choose corrosion-resistant models with the W suffix (such as ALP2A-D-25-W), made of stainless steel or special coating materials.
   High temperature/low temperature medium
   High temperature: When the long-term operating temperature is ≤120℃, choose the V suffix model (such as ALP3A-D-135-V), and the temperature resistance of the pump body reaches 120℃.
   Low temperature: -40℃ environment, choose the ST suffix model to avoid sealing failure.
   Viscosity and solid content
   When the viscosity is >500 mm2/s, the speed needs to be reduced (such as 500-1000 rpm); when the solid content is ≥1%, open gears or wear-resistant materials need to be selected to prevent clogging.
3. Installation and structural adaptation
   Space constraints
   Compact scene: choose ALP1 for small flow (such as ALP1-D-6, small size); choose ALP4 for large flow (such as ALP4-D-130).
   Installation method: Horizontal installation is suitable for conventional scenarios, and vertical installation (without shaft seal) is suitable for space-restricted environments.
   Seal type
   Magnetic seals are used for highly toxic/flammable media, and mechanical seals are used for ordinary media (such as ALP3-D-120 standard double-end mechanical seals).
4. Handling of special working conditions
   Cavitation prevention
   High-temperature media need to calculate the effective cavitation margin (NPSHa) > necessary cavitation margin (NPSHr), and install reverse irrigation if necessary.
   Pulsation and noise control
   ALP2A optimized model (noise reduction design) is preferred for high-precision systems to avoid flow fluctuations affecting equipment stability.

ALP1 gear pump model : ALP1-D-2, ALP1-D-3, ALP1-D-4, ALP1-D-5, ALP1-D-6, ALP1-D-7, ALP1-D-9, ALP1-D-11, ALP1-D-13, ALP1-D-16, ALP1-D-20
ALP1A-D-2, ALP1A-D-3, ALP1A-D-4, ALP1A-D-5, ALP1A-D-6, ALP1A-D-7, ALP1A-D-9

ALP2 gear pump model : ALP2-D-6, ALP2-D-9, ALP2-D-10, ALP2-D-12, ALP2-D-13, ALP2-D-16, ALP2-D-20, ALP2-D-22, ALP2-D-25, ALP2-D-30, ALP2-D-34, ALP2-D-37, ALP2-D-40, ALP2-D-50
ALP2A-D-6, ALP2A-D-9, ALP2A-D-10, ALP2A-D-12, ALP2A-D-13, ALP2A-D-16, ALP2A-D-20, ALP2A-D-22, ALP2A-D-25, ALP2A-D-30, ALP2A-D-34, ALP2A-D-37, ALP2A-D-40, ALP2A-D-50

ALP3 gear pump model: ALP3-D-30, ALP3-D-33, ALP3-D-40, ALP3-D-50, ALP3-D-60, ALP3-D-66, ALP3-D-80, ALP3-D-94, ALP3-D-110, ALP3-D-120, ALP3-D-135
ALP3A-D-30, ALP3A-D-33, ALP3A-D-40, ALP3A-D-50, ALP3A-D-60, ALP3A-D-66, ALP3A-D-80, ALP3A-D-94, ALP3A-D-110, ALP3A-D-120, ALP3A-D-135

ALP4 series gear pump model: ALP4-D-130, ALP4-D-160, ALP4-D-190, ALP4-D-220, ALP4-D-250, ALP4-D-270, ALP4-D-300
ALP4E-D-130, ALP4E-D-160, ALP4E-D-190, ALP4E-D-220, ALP4E-D-250, ALP4E-D-270, ALP4E-D-300
ALP4A-D-130, ALP4A-D-160, ALP4A-D-190, ALP4A-D-220