How to determine the appropriate model for Dalian Chemical Pump parameters

Dalian Chemical Pump is a key equipment for transporting corrosive, viscous, solid and other special media in chemical production. Choosing the right model directly affects production efficiency and safety. Many people only focus on flow rate and head when selecting pumps, but ignore core parameters such as medium characteristics and materials, resulting in frequent pump damage, leakage, and even accidents. Starting from the core parameters, this article teaches you how to systematically select the appropriate chemical pump.

1、 Flow and Head: Basic Framework for Pump Selection

Flow rate and head are the "basic disks" of the pump, which need to be accurately matched with actual needs:

Flow rate (Q): The volume (m ³/h) or mass (t/h) of the conveyed medium per unit time, which needs to be determined according to the process requirements. For example, if the production line requires 50m ³ of dilute sulfuric acid per hour, the pump flow rate should be ≥ 50m ³/h to avoid "big horses pulling small cars" (flow rates far exceeding demand will increase energy consumption and reduce efficiency).

Head (H): The ability of a pump to overcome resistance (in meters of water column), which is a parameter that is prone to errors. Correct calculation method: Actual head=Vertical lifting height+Pipeline frictional loss along the way+Local loss (elbows, valves)+Outlet pressure (such as reactor pressure). For example, if the vertical height is 10m, the pipeline loss is 5m, and the outlet pressure is 0.2MPa (≈ 20m head), the actual head is 35m. When selecting a pump, the head should be slightly higher than the actual value (such as 35-40m). If it is too high, it will cause overcurrent damage to the motor, and if it is too low, it will not meet the conveying requirements.

2、 Medium characteristics: the "soul parameter" of chemical pumps

The essential difference between chemical pumps and ordinary pumps lies in their ability to handle special media, which is the core of pump selection:

Corrosivity: The type of medium (acid/alkali/salt), concentration, and temperature determine the material. For example:

Dilute sulfuric acid (<50% concentration,<80 ℃) → 316L stainless steel;

Concentrated hydrochloric acid (>30%) → fluoroplastic (PVDF/F46) pump;

High temperature strong alkali (120 ℃ NaOH) → fluoroplastic or Hastelloy;

Attention: An increase in temperature will exacerbate corrosion, so it is necessary to choose temperature resistant materials (fluoroplastic pumps with a temperature resistance of ≤ 120 ℃ and alloys for high temperatures).

Viscosity: The viscosity of the medium (cp) affects the selection of pump type. Centrifugal pumps are suitable for low viscosity (<200cp, such as water); For viscosity>500cp (such as engine oil, syrup), a positive displacement pump (gear pump, screw pump) should be selected. If a centrifugal pump is forcibly used to transport high viscosity media, it will cause a decrease in flow rate and motor overload.

Solid content: Solid particles (such as mud) need to be wear-resistant and anti clogging. When the particle diameter is greater than 1mm and the concentration is greater than 5%, the centrifugal pump should choose an open impeller (unobstructed) with high chromium cast iron or rubber lining material; If the solid content is high, use a slurry pump or screw pump.

3、 Material, shaft seal and installation: details determine success or failure

Material matching: Reject 'compromise'. For example, 304 stainless steel used for transporting concentrated hydrochloric acid will rapidly corrode and fluoroplastics must be used; Chlorine containing media (sodium hypochlorite) cannot use 304 (which is prone to stress corrosion), and 316L or fluoroplastic is required.

Shaft seal form: Balancing sealing and safety:

Mechanical seal: with a small leakage rate (<0.1ml/h), suitable for flammable, explosive/toxic media (such as methanol);

Magnetic seal: leak free (magnetic power transmission), suitable for highly toxic/valuable media (such as acrylonitrile), but expensive and cannot be used for idle operation;

Packing seal: Low cost but high leakage, suitable for non-toxic media.

Installation conditions: Choose a vertical pump for small space; Self suction is required from the suction pump; Explosion proof motors (Exd II BT4 and above) with flammable and explosive media; Outdoor installation requires rain and dust protection.

4、 Summary of pump selection steps

Clear requirements: record medium characteristics (type, concentration, temperature, viscosity, solid content), flow rate, actual head;

Preliminary selection of pump type: centrifugal pump/positive displacement pump based on viscosity and solid content;

Determine the material: choose stainless steel/fluoroplastic/alloy according to corrosiveness;

Matching details: shaft seal (mechanical/magnetic), explosion-proof rating, installation form;

Efficiency verification: Select pumps that operate in the high-efficiency zone (with low energy consumption and long lifespan).

The selection of chemical pumps is not a simple comparison of parameters, but a balance between process, safety, and cost. By mastering the above core parameters, one can select a pump that is both user-friendly and durable, providing strong support for production.