Comprehensive guide on select the right chemical pumps
1. Selection Criteria
1.1 Physical and Chemical Properties of the Conveyed Medium
The physical and chemical properties of the conveyed medium directly influence the pump’s performance, material selection, and structural design, making them critical factors in the selection process. These properties include:
- Medium name
- Medium characteristics (e.g., corrosiveness, abrasiveness, toxicity)
- Solid particle content and particle size
- Density
- Viscosity
- Vapor pressure
Additionally, the gas content in the medium should be specified if necessary, along with whether the medium is prone to crystallization.
1.2 Process Parameters
Process parameters serve as the most critical basis for pump selection and should be carefully determined based on the process flow and operational variations.
1.2.1 Flow Rate (Q)
The flow rate refers to the volume of medium required to be transported by the pump in the production process. Process engineers typically provide the normal, minimum, and maximum flow rates.
Pump datasheets usually list only the normal and rated flow rates. When selecting a pump, the rated flow rate must not be less than the system’s maximum flow rate or should be 1.1–1.15 times the normal flow rate.
1.2.2 Head (H)
The head refers to the required lift for the process system, also known as the calculated head. Generally, the pump’s rated head should be 1.05–1.1 times the system’s required head.
1.2.3 Inlet Pressure (Pa) and Outlet Pressure (Pa)
The inlet and outlet pressures refer to the pressure at the pump’s connection flanges. These pressures influence the casing’s pressure resistance and sealing requirements.
1.2.4 Temperature (T)
Temperature (T) refers to the medium temperature at the pump inlet. The process should specify the normal, minimum, and maximum temperatures at the pump inlet.
(Example: The liquid temperature is approximately 80°C, with a maximum of around 120°C and a minimum at ambient temperature.)
1.2.5 Net Positive Suction Head Available (NPSHa)
Also referred to as the effective net positive suction head.
1.2.6 Operating Conditions
Operating conditions are categorized into two types: continuous operation and intermittent operation.
1.3 Site Conditions
Site conditions include the pump’s installation location (indoor/outdoor), ambient temperature, relative humidity, atmospheric pressure, atmospheric corrosion conditions, and hazardous area classification.
2. Selection of Pump Type
The pump type should be selected based on the process parameters of the system, the physical and chemical properties of the conveyed medium, operating cycle, and structural characteristics of the pump. The figure below provides a pump type selection flowchart for reference. Using this flowchart, the appropriate pump type can be preliminarily determined according to system parameters and medium characteristics.
Centrifugal pumps offer advantages such as simple structure, smooth flow without pulsation, and easy flow regulation. Therefore, centrifugal pumps should be the preferred choice unless specific conditions dictate otherwise.
2.1 When metering is required, a metering pump shall be selected.
2.2 low-flow high-head centrifugal pump
When extremely high head is required with very low flow rate and no suitable low-flow high-head centrifugal pump is available, a reciprocating pump may be selected; if NPSH requirements are not stringent, a vortex pump could also be considered.
2.3 axial flow pumps or mixed flow pumps
For applications requiring very low head and large flow rates, axial flow pumps or mixed flow pumps may be selected.
2.4 screw pumps
For media with high viscosity (greater than 650-1000 mm²/s), rotary pumps such as screw pumps or reciprocating pumps may be considered. For exceptionally high viscosity applications, specially designed high-viscosity screw pumps or high-viscosity reciprocating pumps should be selected.
2.5 vortex pumps
For media with gas content exceeding 5%, small flow rates and viscosity below 37.4 mm²/s, vortex pumps may be selected. Where flow pulsation is permissible, reciprocating pumps may be considered as an alternative.
2.6 self-priming centrifugal pumps
For applications requiring frequent start-ups or where pump priming is inconvenient, self-priming pumps should be selected, such as self-priming centrifugal pumps, self-priming vortex pumps, or positive displacement pumps.
3. Selection of Pump Series and Materials
The pump series refers to pumps of the same structural type and application purpose produced by manufacturers, such as:
- IS series clean water pumps
- Y series oil pumps
- ZA series chemical process pumps
- SJA series chemical process pumps
Once the pump type is determined, the appropriate series and materials can be selected based on process parameters and medium characteristics.
3.1 Selection Criteria for Centrifugal Pumps
After confirming the use of centrifugal pumps, the following factors should be considered:
For medium characteristics, select the appropriate specialized pump type:
• Clean water pumps (for non-corrosive fluids)
• Corrosion-resistant pumps
• Chemical process pumps
• Slurry pumps (for media containing solids)
Special medium requirements:
✓ For highly toxic, precious, or radioactive media where leakage is unacceptable:
- Consider sealless pumps (canned motor pumps or magnetic drive pumps)
- Alternatively, use double mechanical seals with leak collection and alarm systems
✓ For volatile liquids (e.g., liquefied hydrocarbons):
- Select pumps with low NPSH requirements (e.g., barrel-type pumps)
3.2 Selection Based on Installation Conditions
- The appropriate pump configuration shall be determined according to site installation requirements:
- • Horizontal pumps – Standard choice for most general installations
• Vertical pumps – Including: - Submerged pumps (for liquid immersion applications)
- Pipeline pumps (for direct pipeline mounting)
3.3 Flow Rate Based Pump Selection
The suction configuration shall be determined according to required flow capacity:
• Single-suction pumps
Recommended for standard flow applications
Typical selection for most industrial processes
• Double-suction pumps
Preferred for high flow rate requirements
Offers balanced axial thrust and improved NPSH characteristics
• Low-flow centrifugal pumps
Specialized design for flow rates below 10 m³/h
Used in precision dosing or micro-flow applications
Technical Considerations:
Flow range compatibility
NPSH requirements
Hydraulic balance needs
Efficiency optimization
3.4 Selection Based on Head Requirements
The pump stage configuration shall be determined according to the required head:
Single-stage pumps
Suitable for low to medium head applications
Simple construction and lower maintenance
Multi-stage pumps
Recommended for high head requirements
Energy efficient for large pressure increases
High-speed centrifugal pumps
Used for very high head with compact design
Requires precise balancing and robust bearings
Final Selection Process:
After determining the above parameters, the appropriate pump series and manufacturer can be selected based on:
Unique characteristics of each pump series
Manufacturer’s production capabilities and quality standards
Additional Considerations for Metering Pump Selection:
A. Hazardous Media Applications
For flammable, explosive, highly toxic or precious liquids:
Diaphragm metering pumps are preferred
Double-diaphragm pumps with rupture alarm should be used to:
- Prevent media/hydraulic oil mixing
- Provide immediate failure detection
B. Flow Control Options
Standard: Manual adjustment
Automatic control options:
- Electric actuation
- Pneumatic actuation
SDP Pump is not just a supplier — we are your long-term engineering partner.
Conclusion
SDP Pump is not just a pump supplier — we are your long-term engineering partner.
From process analysis and pump selection to lifecycle support, SDP Pump delivers reliable, efficient, and customized pumping solutions for demanding industrial applications worldwide.
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