In water treatment, chemical processing, petroleum, agriculture, construction, and domestic fields, water pumps are the core equipment for liquid transfer. Faced with dozens of pump types and hundreds of models, choosing the most suitable pump for a given condition is a challenge that puzzles many engineers and users. Starting from working principles, this article provides a comprehensive analysis of all major types of pumps under three categories: dynamic pumps, positive displacement pumps, and special pumps. Each major type is further broken down into all its main models, with detailed explanations of application scenarios, operating methods, and uses for every single model. This guide aims to be a complete reference manual for your pump selection process.
English keywords: types of water pumps, centrifugal pump selection guide, submersible pump models, screw pump applications, gear pump specifications, positive displacement pump, dynamic pump, magnetic drive pump, self priming pump, multistage centrifugal pump, slurry pump selection, diaphragm pump uses.
1. Three-Level Classification System of Water Pumps by Working Principle
Water pumps can be classified from multiple angles, but the most scientific method is by working principle. According to internationally accepted standards, water pumps are first divided into three major categories, of which the first two are most commonly used: dynamic pumps (also called kinetic pumps, which impart kinetic energy to the liquid through a rotating impeller) and positive displacement pumps (which transport liquid through periodic changes in chamber volume). A third category includes special pumps for specific applications. Within each major category, many specific models exist and will be detailed one by one.
Long‑tail keywords: water pump classification by working principle, difference between dynamic pump and positive displacement pump, complete list of water pump types and models.
1.1 Dynamic Pumps (Kinetic Pumps)
The core component of a dynamic pump is the impeller. When the impeller rotates at high speed, the blades do work on the liquid, giving it kinetic energy, which is then partially converted into pressure energy in the pump casing. Dynamic pumps feature simple structure, large flow capacity, smooth operation, high rotational speed, compact size, light weight, high efficiency, steady flow without pulsation, stable performance, easy operation, and convenient maintenance. They are the most widely used type in industrial and agricultural production.
Based on impeller structure and flow direction, dynamic pumps are further divided into five major categories: centrifugal pumps (single‑stage, multistage), axial flow pumps, mixed flow pumps, vortex pumps, and submersible electric pumps – submersible pumps are essentially an integrated form of centrifugal, axial‑flow, and mixed‑flow pumps designed for underwater operation. Except where special requirements exist, centrifugal pumps should be the first choice. When metering accuracy is needed, choose a metering pump. When very high head and very low flow are required, a reciprocating pump or vortex pump may be used. When very low head and very large flow are needed, axial‑flow or mixed‑flow pumps are appropriate. When the liquid is highly viscous, rotary positive displacement pumps or reciprocating pumps should be considered.
1.2 Positive Displacement Pumps
Positive displacement pumps rely on periodic volume changes in a closed chamber to suck in and discharge liquid. They can generate very high pressures and are suitable for high‑viscosity, high‑pressure, and low‑flow conditions. Positive displacement pumps are divided into reciprocating pumps and rotary pumps based on the motion of internal components.
· Reciprocating pumps: include piston pumps, plunger pumps, and diaphragm pumps. They use the reciprocating motion of a piston or plunger to change chamber volume. They can produce extremely high pressures (up to 100 MPa or more), making them the first choice for high‑pressure cleaning, oilfield water injection, etc.
· Rotary pumps (rotor pumps) : include gear pumps, screw pumps, vane pumps (note: these are different from the “vane pump” in hydraulics), lobe pumps, sliding vane pumps, peristaltic pumps, and cam pumps. Their key characteristic is that flow is proportional to rotational speed, while pressure has little effect, making them suitable for high‑viscosity media.
1.3 Special Types of Pumps
Beyond dynamic and positive displacement pumps, there are pumps based on other operating principles, including magnetic drive pumps, canned motor pumps, self‑priming pumps, jet pumps, hydraulic ram pumps, air‑operated diaphragm pumps (which are a hybrid of reciprocating and pneumatic drive), and others. These are often developed to meet specific needs such as zero leakage, self‑priming, or handling special fluids.
2. In‑Depth Analysis of All Centrifugal Pump Series
Centrifugal pumps are the most widely used type of dynamic pumps, accounting for more than 70% of total pump products. They are the workhorses for liquid transfer in industry, agriculture, municipal services, and construction. The basic principle: a high‑speed impeller rotates, liquid is thrown outward by centrifugal force, kinetic energy is converted to pressure energy, and liquid is delivered. Centrifugal pumps offer large flow, simple structure, smooth operation, high speed, compact size, light weight, high efficiency, steady flow, stable performance, and easy maintenance.
If no special requirements exist, centrifugal pumps should be given priority.
2.1 IS/IH Series – International Standard Chemical Centrifugal Pumps
IH type stainless steel centrifugal pump is a single‑stage single‑suction centrifugal pump suitable for transporting various corrosive media at temperatures up to 80°C. Made of stainless steel, it offers corrosion resistance, heat resistance, and wear resistance. Widely used in chemical, pharmaceutical, food, and beverage industries.
IS type clean water centrifugal pump has the same basic structure as IH. It is suitable for delivering clean water or liquids with physical and chemical properties similar to clean water, such as municipal water supply, fire protection, building water drainage, and agricultural irrigation. It is the standard configuration for clean water in civil and industrial applications. Centrifugal pumps are suitable for low‑to‑medium viscosity liquids, provide relatively high head, and are simple and easy to maintain.
IHF series fluoroplastic chemical centrifugal pump is an upgraded corrosion‑resistant version based on the IS pump. Its rating, current characteristics, and specifications are equivalent to national industry standards. It is the replacement product designated by the Ministry of Machinery Industry for the old F‑series corrosion‑resistant centrifugal pumps. Delivery medium temperature generally ranges from -20°C to 200°C (for temperatures above 120°C, a water‑cooled mechanical seal is required). This pump uses a new hydraulic model, with efficiency about 5% higher than ordinary pumps. It features a thickened shaft, extended bearing housing, upgraded bearings, and reduced overhang, making its performance more stable. Depending on load, it can be equipped with internal, external, or cartridge mechanical seals, and can handle a wide range of media. It is one of the most popular chemical pump series today. The IH magnetic drive version is also available and is widely used for conveying corrosive media such as acids, alkalis, and salts.
FSB series fluoroplastic centrifugal pump is another common stainless steel corrosion‑resistant pump type, mainly used in chemical, pharmaceutical, electroplating, and petroleum industries to transport highly corrosive liquids. It complements the IHF series in structure and applications.
Applications and selection advice: The IH/IHF series are the main choice for conveying corrosive chemicals in chemical and pharmaceutical plants. For general acid/alkali salt solutions (e.g., dilute sulfuric acid, hydrochloric acid, sodium hydroxide solution), the IH stainless steel pump is preferred. For highly corrosive media (e.g., concentrated sulfuric acid, hydrofluoric acid, mixed acids), upgrade to the IHF fluoroplastic pump.
2.2 ISG/ISW Series – Vertical/Horizontal In‑Line Centrifugal Pumps
ISG type stainless steel vertical centrifugal pump is a single‑stage single‑suction centrifugal pump for conveying clean water or similar liquids at temperatures up to 80°C. It features a simple structure, smooth operation, and low noise. The vertical design saves floor space and can be mounted directly on the pipeline. Because of its compact footprint, it is widely used in building pressurization, chilled water circulation in HVAC, hot water heating, etc. In‑line pumps are widely used in municipal water supply, high‑rise building water supply, and fire protection systems, offering reliable operation.
ISW type horizontal in‑line centrifugal pump is the horizontal installation counterpart of the ISG. Also suitable for clean water and similar liquids. The horizontal configuration allows the use of standard motors and baseplates, making maintenance easier, but it occupies more space. It is suitable for applications where space is not restricted.
SG series pipeline pump: Model designation example: 50SG15-30 – 50 indicates pump size (discharge nominal diameter), SG indicates SG type pipeline centrifugal pump, 15 indicates flow classification, 30 indicates first‑stage impeller trimming. SGR type is for hot water pipeline centrifugal pumps, suitable for heating systems.
SPG series canned motor pipeline pump is a special form of pipeline pump with a canned motor – no dynamic seal, no leakage. Example: SPG80-200(I)A – SPG stands for canned motor pipeline centrifugal pump, 80 is nominal diameter of inlet/outlet, 200 is impeller nominal outside diameter. SPG(R) is for hot water, SPG(T) for corrosive fluids, SPG(B) for explosion‑proof applications.
Application scenarios: ISG/ISW series are the first choice for building water supply/drainage, HVAC chilled water circulation, and industrial cooling water systems. Their biggest advantages are easy installation and small footprint, especially suitable for machine room retrofits where space is limited.
2.3 CQ/CQB/CQG/CQ Series – Magnetic Drive Centrifugal Pumps
CQ series stainless steel magnetic drive centrifugal pump is suitable for transporting various corrosive media at temperatures up to 100°C. It uses magnetic drive, requires no mechanical seal, and offers leak‑free operation and stable running.
CQB type stainless steel magnetic drive centrifugal pump is a leak‑free centrifugal pump using magnetic drive, no mechanical seal, suitable for various corrosive media at temperatures up to 100°C. It features compact structure, stable operation, and easy maintenance.
The CQB series fluoroplastic magnetic drive pump uses magnetic coupling, so there is no dynamic seal point, completely eliminating leaks that occur with shaft seals in conventional pumps. Its wetted parts are made of fluoroplastic and high‑purity industrial ceramics, providing excellent corrosion resistance and sealing performance. Therefore, it is widely used in chemical, pharmaceutical, aluminum foil, acid production, coating, non‑ferrous metals, and other industries, as well as for flammable, explosive, volatile, toxic, organic solvent, and valuable liquids.
CQB series magnetic drive centrifugal pumps are suitable for petroleum, chemical, pharmaceutical, smelting, electroplating, environmental protection, food, film processing, water treatment, national defense, and other industries. They are ideal for conveying flammable, explosive, volatile, toxic, rare valuable liquids, and various corrosive liquids. The basic construction includes an impeller, magnetic coupling, and motor. Best results are obtained with low‑viscosity liquids, but the pump must be primed before each start.
CQG type stainless steel high‑temperature magnetic drive centrifugal pump is suitable for high‑temperature liquids up to 350°C. Made of stainless steel, it offers heat resistance, corrosion resistance, and leak‑free operation.
ZCQ type stainless steel self‑priming magnetic drive centrifugal pump is a self‑priming centrifugal pump using magnetic drive, no mechanical seal, suitable for various corrosive media at temperatures up to 100°C. It features good self‑priming performance, leak‑free operation, and stable running.
Application scenarios and methods: When the medium is highly corrosive or toxic, or when “zero leakage” is required on site (e.g., chemical workshops, pharmaceutical clean areas, flammable/explosive zones), choose a magnetic drive pump instead of a mechanically sealed centrifugal pump. CQ and CQB are for general applications, CQG for high temperatures, ZCQ for high suction lift (self‑priming needed). Magnetic drive pumps are suitable for low‑viscosity media, large flow, low head, but must be primed before starting.
2.4 WFB/QW Series – Non‑Clogging Centrifugal Pumps
WFB type stainless steel non‑clogging centrifugal pump is designed to handle liquids containing suspended particles, fibers, etc., at temperatures up to 80°C. Features non‑clogging, stable operation, easy maintenance.
QW type submersible mixing pump is for mixing and agitation, flow 5-2000 m³/h, head 5-60 m, power 0.75-250 kW, voltage 380V/660V/1140V. Suitable for municipal wastewater treatment, industrial wastewater treatment, domestic sewage, etc.
The WFB/QW series are centrifugal pumps specifically designed to handle easily clogged media containing solid particles or short fibers. The impeller has a non‑clogging design (wide passages or open impeller). They are widely used in papermaking, textile printing and dyeing, food processing, etc.
2.5 Multistage Centrifugal Pump Series (DL/LG/QDL/D/DG/DF/MD)
Multistage centrifugal pumps use multiple impellers in series (stages) to achieve high pressure (high head). They are core equipment for high‑pressure water supply, boiler feedwater, oilfield water injection, and other high‑pressure applications.
DL/LG/QDL type vertical multistage centrifugal pump: Compact size, small footprint, easy installation. Suitable for high‑rise building water supply, fire pressurization, boiler make‑up water, etc. QDL is stainless steel, offering better corrosion resistance.
D type horizontal multistage centrifugal pump: Suitable for delivering clean water or liquids with similar properties. Widely used in industrial and mining water supply/drainage, farmland irrigation, etc. The multiple stages achieve high head. Operation is stable and reliable.
DG type boiler feed pump: Designed for boiler systems, resistant to high temperature and high pressure. Core equipment for thermal power plants and industrial boilers.
DF type stainless steel corrosion‑resistant multistage pump: Wetted parts are stainless steel, suitable for corrosive liquids. Widely used in chemical, petroleum, pharmaceutical industries for high‑pressure transfer. When handling corrosive media with high head requirements, choose the DF series stainless steel multistage pump.
MD type wear‑resistant multistage pump: Wetted parts are made of high‑chromium alloy or cemented carbide for wear resistance. Ideal for conveying mine water containing solid particles in coal mines and concentrators. It satisfies high head demand while effectively resisting wear, greatly extending service life.
Application scenarios: High‑rise building water supply (DL/LG series), boiler feedwater (DG series), oilfield water injection and high‑pressure corrosive media transfer (DF series), coal mine drainage and tailings transport (MD series).
2.6 Self‑Priming Centrifugal Pump Series (FZB/ZMD)
When the liquid level is below the pump installation point, choose the FZB self‑priming pump. If leak‑proofness is also required, choose the ZMD magnetic drive self‑priming pump.
FZB series fluoroplastic self‑priming centrifugal pump: Wetted parts are fluoroplastic. The shaft seal uses an advanced external‑type bellows mechanical seal, adjustable. Self‑priming height is 3-4 meters, eliminating the need for flooded suction, priming water, or foot valves. Widely used in pickling, acid/alkali production, chemical, pesticide, papermaking, electronics industries. The FZB lined ultra‑strong self‑priming pump has flow 2-28 m³/h, head 12-45 m, self‑priming height up to 7 m, especially suitable for applications where the pump is frequently moved and must handle drums with different media.
ZMD type magnetic drive self‑priming pump: Combines zero leakage of magnetic drive pumps with self‑priming capability. The safest choice for transferring drummed hazardous chemicals in the chemical industry.
GBF type lined fluoroplastic pipeline pump: Manufactured by fluoroplastic hot‑melt compression molding, offering extremely strong corrosion resistance. This new type of pipeline centrifugal pump has a compact structure – the impeller is directly coupled to the motor via a bracket. The bellows external mechanical seal is stable and reliable. Excellent hydraulic performance. All wetted parts are made of perfluorinated materials (FEP, PFA), providing very strong corrosion resistance.
3. In‑Depth Analysis of All Submersible Pump Series
Submersible pumps are designed with motor and pump body integrated, operating fully submerged in water. Because the motor works underwater, it must have excellent waterproof and sealing properties to prevent water ingress and motor burnout. Submersible pumps are especially suitable for deep well water extraction, sewage lifting, and mine dewatering.
3.1 Submersible Sewage Pump Series (WQ/QW/AS/AV/JYWQ)
WQ (QW) submersible non‑clogging sewage pump is the most common type. Diameter range 25-500 mm. Model interpretation: 80WQ(QW)P40-15-4 – 80 is pump diameter (mm), WQ(QW) stands for submersible sewage pump, P stands for stainless steel material, 40 is flow (m³/h), 15 is head (m), 4 is motor power (kW). Suitable for municipal wastewater treatment, industrial wastewater treatment, construction drainage, etc.
AS/AV type submersible sewage pump: More compact structure, suitable for small treatment facilities. AS type has a shredding mechanism to cut fibrous solids.
JYWQ type automatic mixing submersible sewage pump: Diameter range 50-250 mm. Adds mixing function to the WQ to prevent sludge deposition at the tank bottom, improving sewage discharge efficiency.
BQW flameproof submersible pump: Designed for coal mines and similar applications to convey slurries and coal dust. Requires explosion‑proof motor to prevent ignition of flammable gas. When conveying media containing solid impurities such as flood control, construction drainage, farm purification, choose QX, QDX types.
3.2 Deep Well / Borehole Submersible Pump Series (QJ/QS/QSPD/QSF)
QJ type deep well submersible pump (borehole pump) : Diameter range 40-120 mm, flow 5-2400 m³/h, head 10-600 m, power 7.5-410 kW. Suitable for agricultural irrigation, water supply, factories, mining – large flow, high head deep well extraction. For well diameter 200 mm (8 inches), choose models with frame size 200QJ or smaller; for 250 mm (10 inches), choose 250QJ or smaller.
QS type small submersible pump: QS, QY, QX, QD belong to small submersible pumps.
QSPD type single‑phase stainless steel submersible pump: Diameter 25 mm, flow 1.5-4 m³/h. Suitable for residential basement drainage, small well water extraction, aquarium circulation, and other single‑phase power applications. For clean water extraction from rivers, shallow wells, lakes, prioritize Q series high‑head submersible pumps, QY oil‑filled submersible pumps, QDJ deep well submersible pumps, and QDX small submersible pumps.
QSP type submersible pump: Mainly for construction drainage, mining dewatering, factory drainage, flow 10-600 m³/h, head 5-80 m, power 0.75-250 kW.
QY type submersible pump (oil‑filled) : Widely used in municipal water supply, industrial production, mining dewatering. The QY series is filled with transformer oil, enhancing motor heat dissipation and insulation. Strong moisture resistance, suitable for long‑term submerged operation.
QXF type stainless steel submersible pump: For conveying slightly corrosive clean water or sewage. Ideal for drainage in clean workshops in food, pharmaceutical, chemical industries.
QY/QJ applications: For clean water extraction from rivers, shallow wells, lakes, prioritize QY, QJ, QS types. For flood control, construction, farm purification, choose QX, QDX types.
Selection tip: When choosing a borehole submersible pump, first determine the pump frame size based on well diameter (100 mm, 150 mm, 200 mm, 250 mm, 300 mm, etc.), then select the specific model based on actual flow and head.
4. In‑Depth Analysis of All Screw Pump Series
Screw pumps are positive displacement rotary pumps where the volume change of sealed chambers formed by screws and liners draws in and discharges liquid. Screw pumps are broadly classified into single‑screw, twin‑screw, and triple‑screw pumps, each suitable for different conditions and media. Characteristics: stable flow, low pressure pulsation, self‑priming ability, low noise, high efficiency, long life, reliable operation. A notable advantage is that they do not create turbulence and are insensitive to viscosity, allowing them to handle high‑viscosity media.
4.1 Single‑Screw Pump Series (G/WG/GL)
Single‑screw pumps have a single‑start external thread rotor that rotates eccentrically inside a double‑start internal thread stator (the stator is soft), always maintaining engagement.
G type single‑screw pump is the most widely used. Performance parameters: G20-1 flow 0.8-1.5 m³/h, pressure 0.6 MPa, suitable for laboratory small flow; G70-1 flow 10-25 m³/h, pressure 1.2 MPa, suitable for high‑viscosity media like sludge and paints. Single‑screw pumps are a new type of internal‑mesh rotary positive displacement pump. They require no valves, and flow is steady and linear. Compared to plunger pumps, they have better self‑priming capacity. Compared to diaphragm pumps, they can handle mixtures containing gas, solid particles, or fibers, as well as corrosive materials. Compared to gear pumps, they can handle high‑viscosity substances. They can also be used for pharmaceutical filling and metering. GL type single‑screw pumps are often used in food and pharmaceutical industries.
WG type stainless steel screw pump: Mainly for high‑hygiene applications like food and beverage, pharmaceuticals. All stainless steel design, CIP cleanable. A type of stainless steel sanitary screw pump.
Unique performance and maintenance: Single‑screw pumps can handle liquids containing solid particles. They work with almost all viscous fluids, especially high‑viscosity and non‑Newtonian fluids. Operating temperature is limited by stator material. When pumping high‑viscosity materials such as sludge, jam, chocolate syrup, low speed operation is necessary to avoid shortening stator rubber life. For G type pumps, besides output pressure, the rotor/stator linear speed must be accurately calculated – excessive speed will quickly degrade the rubber sleeve, causing pressure pulsation and flow loss. Flow up to 150 m³/h, pressure up to 20 MPa.
4.2 Twin‑Screw Pump Series (2G/2GG/W/V/V/S/SM/SN)
Twin‑screw pumps use two meshing screws (drive and driven) to form sealed chambers, with minimal clearance of 0.05-0.15 mm. Features: no agitation, no pulsation, smooth handling of various media, very strong self‑priming ability, and gas‑liquid mixed transport. Because clearances are constant, twin‑screw pumps can handle gas‑liquid mixtures – a unique advantage. They can also run dry briefly: since moving parts do not contact, short no‑load operation does not damage core parts. Externally‑bearing twin‑screw pumps are widely used in oilfields, chemical, and marine industries, with media temperatures up to 250°C.
Externally‑bearing twin‑screw pump: Not only suitable for lubricating oils, but also for high‑viscosity non‑lubricating non‑abrasive media, as well as corrosive media like various acids and alkalis. Flow 6-600 m³/h, up to 1600 m³/h. Liquid viscosity should generally not exceed 1500 mm²/s. Especially suitable for lubricating oil, grease, crude oil, asphalt, fuel oil and other high‑viscosity oils.
Stainless steel twin‑screw pump: Suitable for petroleum, chemical fiber, metallurgy, machinery, marine, glass, and many other industries. Core equipment for crude oil and asphalt pipeline transport.
3QGB heat‑jacketed twin‑screw pump: With a heat jacket, useful for media that solidify at room temperature (e.g., asphalt, paraffin). A heat medium keeps the fluid flowing.
4.3 Triple‑Screw Pump Series (3G/3GCL/SNH/SM)
Triple‑screw pumps consist of one drive screw and two idler screws. The drive screw directly drives the idler screws without needing gears. Simple construction. The pump body itself acts as bearings for the screws, requiring no radial bearings, so screws can be very long to achieve high pressure. Triple‑screw pumps are not suitable for liquids containing solid impurities >600 µm. They can operate at high speed, are high‑efficiency small‑flow pumps, and the stuffing box sees only suction pressure, so leakage is minimal.
Triple‑screw pumps can achieve pressures up to 70 MPa (far exceeding single or twin‑screw), flow up to 2000 m³/h. Suitable for viscosities 5-250 mm²/s, for lubricating oil, heavy oil, light oil, crude oil, glycerin, viscose and other high‑viscosity fluids. Triple‑screw pumps are widely used in petroleum, chemical fiber, metallurgy, machinery, electric power, machine tools, marine, glass, highway, and many other industries. For applications requiring stable pressure, such as machine tool hydraulic systems, marine fuel transfer, oil depots, triple‑screw pumps are often a better choice. In metallurgical or forging equipment for high‑pressure hydraulic oil, triple‑screw pumps are also the main choice.
3GCL type vertical triple‑screw pump: vertical mounting, pump inlet at bottom, outlet at top. Suitable for space‑limited applications or where suction level requirements are special. For heavy oil and low‑volatility high‑viscosity liquids, the heat‑jacketed 3QGB triple‑screw pump is recommended.
5. In‑Depth Analysis of All Gear Pump Series
Gear pumps are among the simplest positive displacement pumps, consisting of two meshing gears and a pump housing. Liquid is drawn in and discharged as the gear teeth rotate. Gear pumps are generally suitable for high‑viscosity, lubricating liquids and not for low‑viscosity non‑lubricating liquids (e.g., pure water). They have poor self‑priming ability and cannot run dry for extended periods. Before first start, they must be primed with the liquid to be pumped and vented of air. Operating pressure can reach 30 MPa. They are core components in hydraulic systems such as injection molding machines and oil presses, as well as lubrication oil transfer systems.
5.1 KCB/2CY Series – External Mesh Involute Gear Pumps
The KCB series is also known as the 2CY series. The two names represent the same pump type but with different pressure unit expressions (KCB uses L/min and MPa, 2CY uses m³/h and kgf/cm²). The basic construction is two identical involute gears rotating in a figure‑8 housing. Liquid enters at the suction port, travels around the housing within the gear teeth, and is expelled when the teeth mesh.
KCB gear pumps are suitable for conveying non‑corrosive liquids without solid particles or fibers, temperature not exceeding 80°C, viscosity 5×10⁻⁶ to 1.5×10⁻³ m²/s (5-1500 cSt), such as lubricating oil or similar liquids. Commonly used as transfer pumps, booster pumps, fuel oil pressurizing pumps, or lubricating oil pumps in industrial facilities. In oil transfer systems, they can serve as transfer or booster pumps. In fuel systems, they can serve as fuel pumps for transfer, pressurization, and injection. In hydraulic systems, they can serve as hydraulic pumps providing hydraulic power. In many industries, they are used as lubricating oil pumps.
Standard KCB pumps come with cast iron. For food and high‑hygiene requirements, 304 or 316L stainless steel gear pumps can be specified. For mildly corrosive media, stainless steel pump body with anti‑spark copper gears and an explosion‑proof motor can be supplied.
Typical KCB model parameters: KCB-18.3 (2CY-1.1/1.45): flow 1.1 m³/h, 1.45 MPa; KCB-33.3 (2CY-2/1.45): flow 2 m³/h, 1.45 MPa; KCB-55 (2CY-3.3/0.33): flow 3.3 m³/h, 0.33 MPa; KCB-83.3 (2CY-5/0.33): flow 5 m³/h, 0.33 MPa; KCB-200 (2CY-12/0.33): flow 12 m³/h, 0.33 MPa; KCB-300 (2CY-18/0.36): flow 18 m³/h, 0.36 MPa; KCB-483.3 (2CY-29/0.36): flow 29 m³/h, 0.36 MPa; KCB-633 (2CY-38/0.28): flow 38 m³/h, 0.28 MPa; KCB-960 (2CY-58/0.28): flow 58 m³/h, 0.28 MPa; KCB-1200: flow 72 m³/h, 0.6 MPa; KCB-1600: flow 95 m³/h; KCB-1800: flow 112 m³/h, 0.6 MPa; KCB-2500: flow 150 m³/h.
YCB type circular arc gear pump is an upgraded design based on KCB. The gear teeth have an arc profile, providing smoother meshing and lower flow pulsation. Performance parameters are roughly equivalent to KCB.
2CY series gear pump evolved from involute gear pumps. Features: valveless, high pressure. 2CY gear pumps can have outlet pressure up to 2.5 MPa, usually driven by a 4‑pole motor, flow 1.08-21 m³/h. Its advantage is high pressure, making it a good choice when long pipelines are needed for lubricating oil loading/unloading. For long‑distance oil supply lines, the 2CY pump can significantly reduce the number of booster stations compared to KCB pumps.
Typical applications and boundary conditions: The pump body has an internal safety valve with set pressure about 1.5 times rated discharge pressure. However, the safety valve cannot permanently replace a line pressure‑reducing valve. If the system requires constant pressure reduction over a long period, an additional valve must be installed. For corrosive chemicals, use all‑stainless steel gears or copper gears. For low‑viscosity solvents like alcohols or gasoline, a small‑clearance pump version is needed to prevent internal backflow that would cause flow and pressure deficiency. Always inform the manufacturer of viscosity.
5.2 YHCB Series Circular Arc Gear Oil Pump – High‑Flow Special Application
The YHCB gear pump uses double circular arc teeth, resulting in smoother, quieter meshing. Flow up to 600 m³/h, discharge pressure 0.6-2.5 MPa. Suitable for oilfield pipelines, port terminals, ship offloading, etc. It is the primary high‑flow pump for long‑distance external transfer.
YHCB pumps are often supplied as bare shafts, ready to be directly connected to piping or hose systems for fast coupling. Widely used in oilfields and large terminal loading/unloading. When required flow exceeds 200 m³/h, using a single YHCB pump reduces footprint by about 40% compared to multiple KCB pumps in parallel, and reduces potential failure points.
5.3 BBG/NYP Series – Internal Mesh High‑Viscosity Special Pumps
BBG type internal mesh cycloidal gear oil pump uses an inner ring gear and a pinion with a crescent separator. Flow pulsation is half that of external mesh pumps. Especially suitable for high‑viscosity liquids such as chocolate, resin, grease, and adhesives. It maintains good efficiency even at high viscosity (1000-5000 cSt) without trapping problems.
NYP type internal ring high‑viscosity pump (NYP series) is a specialised high‑viscosity internal gear pump developed from BBG. Maximum viscosity can exceed 100,000 cSt. Widely used in chemical fiber, petrochemical, oil, coatings, pharmaceutical, and food industries to convey high polymers, adhesives, and high‑viscosity lubricating oils. For extremely high viscosity media (e.g., asphalt, high‑temperature polymer melt), the NYP type internal mesh high‑viscosity pump must be used – KCB external gear pumps would have difficulty meshing.
5.4 LB/2CY Stainless Steel Gear Pumps – Sanitary and Fuel Oil Specials
LB type refrigeration compressor pump is a gear pump specifically for refrigeration compressor lubricating oil systems. Common in refrigeration circuits. The seals are made of fluorine‑resistant material. It is a specialised branch of gear pumps for refrigeration systems.
2CY stainless steel gear oil pump has a stainless steel pump body. Suitable for light oils or slightly corrosive but still lubricating liquids. Especially easy to disassemble for maintenance. Widely used in light oil transfer and marine machinery.
5.5 WCB/BP/CB‑B Series – Micro/Portable/Base‑Mounted Gear Pumps
WCB portable gear oil pump is generally a small pump with a carry handle. Suitable for small‑factory refueling, agricultural machinery maintenance, emergency oil replenishment, and other mobile needs.
BP belt‑drive gear oil pump is connected via a belt pulley to a diesel engine, tractor, or other prime mover. Flow is less stable, but it can be used in rural or remote construction sites without electricity for irrigation or simple oil transfer.
CB‑B micro gear oil pump is a small oil pump with flow mainly 6-100 L/min. Usually used as a charge pump (auxiliary pump) in machine tools, hydraulic power units, and test stands. Axial clearance is not adjustable, and it requires high oil cleanliness. Mostly used in low‑pressure circuits of small systems.
Core selection principle for gear pumps: There are many types. Selection must be based on medium viscosity, corrosiveness, and presence of solid particles. Always strictly follow the pump’s performance curve. KCB and 2CY are general‑purpose external mesh pumps – KCB is standard, 2CY provides higher pressure. YHCB is high‑flow external transfer. BBG (internal mesh) and NYP are for high viscosity. WCB is portable. CB‑B is small hydraulic charge pump. For all models, verify medium viscosity, suction lift, and discharge pressure to avoid exceeding pump limits.
6. In‑Depth Analysis of Other Important Pump Types
6.1 Diaphragm Pump Series (QBY/DBY – Pneumatic / Electric)
Diaphragm pumps use an elastic diaphragm that reciprocates to change chamber volume and deliver fluid. The fluid is completely isolated from moving parts by the diaphragm. Apart from transmission components, wetted parts are made of corrosion‑resistant materials. They feature no leakage and corrosion resistance, making them suitable for toxic, highly corrosive media. Pneumatic diaphragm pumps also offer explosion‑proof performance.
QBY type stainless steel diaphragm pump (pneumatic) : Suitable for various corrosive media, low‑viscosity liquids, liquids with suspended particles, etc., at temperatures up to 150°C. Features no leakage, good self‑priming, stable operation. QBY runs on compressed air – no sparks, controllable operating temperature. It is one of the safest fluid transfer methods in flammable/explosive chemical workshops.
DBY type electric diaphragm pump: Driven by an electric motor. Suitable for applications where explosion protection requirements are lower or compressed air is not available. QBY pumps can run dry almost indefinitely, offering process safety and strong abrasion resistance. In chemical, electronics, food industries for transferring acid/alkali liquids, latex, or adhesives, diaphragm pumps are preferred. For easily solidified or highly corrosive liquids (e.g., concentrated sulfuric acid, hydrofluoric acid), choose QBY stainless steel or PTFE diaphragm pumps to completely eliminate leakage risk or equipment corrosion.
6.2 Plunger Pump/Piston Pump Series – High Precision and High Pressure
Plunger pumps use the reciprocating motion of a plunger in a cylinder to change sealed chamber volume, enabling suction and discharge. Plunger pumps can achieve extremely high pressures, exceeding 100 MPa in high‑pressure versions. Widely used in ultra‑high pressure cleaning equipment, petrochemical hydrogenation, urea plants, etc. Metering pumps, high‑pressure cleaners, and reverse osmosis equipment all use plunger pumps. For high‑pressure pump applications in waterworks or boiler feedwater requiring >1.6 MPa, three‑ or five‑plunger pumps are common.
When accurate metering is required for high pressure and easily cavitating media, choose a plunger‑type metering pump. Plunger pumps are the best choice for precise chemical dosing. Hydraulic power units and oil presses often use axial piston pumps with swashplates. For high‑sand content or seawater injection, valve‑controlled plunger pumps are preferred.
6.3 Axial Flow Pump / Mixed Flow Pump Series – Large Flow, Low Head
When head is very low and flow very large, choose axial flow pumps or mixed flow pumps. Axial flow pumps (ZLB/QZB type) use the lift generated by rotating blades to move water. Suitable for large‑area farmland irrigation and flood control. Characteristics: large flow, low head. In rural drought relief and urban flood emergency, QZB submersible axial flow pumps can shorten rescue time. Mixed flow pumps (HLB type) combine characteristics of centrifugal and axial flow pumps, balancing head and flow. Widely used in drainage pumping stations and circulating water systems.
6.4 Self‑Priming Pump Series (ZCX/FZB/Jet Self‑Priming Pump)
For applications with frequent start/stop or where priming is inconvenient, choose a self‑priming pump. ZCX type self‑priming centrifugal pump has an air‑evacuation feature. After the first prime, the pump retains water inside for subsequent self‑priming. Jet self‑priming pump uses an ejector to create suction. It is the standard for rural domestic pressurization and small construction sites. FZB series fluoroplastic self‑priming pump additionally offers corrosion resistance, suitable for tanker truck and drum chemical handling where pumps are frequently moved.
6.5 Metering Pumps and Dosing Pumps – Full‑Range Precision Control
When precise metering is required, a metering pump must be used. Metering pumps (plunger or diaphragm type) can linearly adjust flow at constant speed. Used for reverse osmosis antiscalant injection and coagulant dosing. Standard plunger metering pumps (J type) are for high‑pressure leak‑free applications. Hydraulic diaphragm metering pumps (JXM type) are for strongly corrosive slurries or high‑viscosity chemical raw materials, equipped with PTFE double diaphragms.
6.6 Canned Motor Pumps and Magnetic Drive Pumps – Completely Leak‑Free Integration
Canned motor pumps have the motor and pump integrated in a fully sealed vertical/horizontal design. They rely on the pumped medium to cool the stator. They can tolerate net positive suction head (NPSH) better than magnetic drive pumps. In water treatment plant chlorine injection, refrigeration systems for ammonia and Freon, and flammable solvent pipelines, canned motor pumps are reliable and require less frequent maintenance.
Magnetic drive pumps use permanent magnetic force for synchronous transmission. They are more common in high‑temperature, high‑pressure environments for corrosive and flammable materials. When handling radioactive valuable liquids or avoiding mechanical seal leakage in GMP cleanrooms, choose a magnetic drive pump over a canned motor pump (canned pumps can overheat if internal circulation flow is insufficient). For highly corrosive media like concentrated sulfuric acid, concentrated nitric acid, or flammable/explosive media where any contamination is unacceptable, choose CQB or ZMD series magnetic drive pumps. If self‑priming is also needed, choose ZMD self‑priming magnetic drive pumps.
6.7 Horizontal/Vertical Slurry Pumps and Dredge Pumps – Solid‑Liquid Two‑Phase Flow
In mining, metallurgy, and power industries, high‑concentration slurries or ash slags containing large amounts of hard solid particles must be handled by slurry pumps. Common slurry pump models are ZJ, SP series, e.g., ZJ, SP, and HH heavy‑duty slurry pumps. They have high‑chromium alloy wear‑resistant liners, offering excellent resistance to abrasion. When using ZJ or AH slurry pumps, operating speed must be reduced, and shaft seal water supply strictly controlled; otherwise, the pump chamber will wear through quickly.
6.8 Vacuum Pumps (2X/SZ/SK Series) – Dedicated for Vacuum Generation
Vacuum pumps are essential for vacuum impregnation, drying equipment, and vacuum conveying processes. 2X series two‑stage rotary vane pumps, SZ series water‑ring vacuum pumps, and SK series slide‑valve pumps can all achieve certain vacuum levels and are key equipment in such systems.
7. Quick Selection by Medium/Condition
Clean water – medium to low head, low corrosion requirement
First choice: IS/ISG/ISW/SG/SGR/SPG series single‑stage centrifugal pumps. For high head: DL/LG multistage centrifugal pumps. For deep well extraction: QJ/QS/QY series submersible pumps. SGR is for hot water, SPG is canned motor type, suitable for hot water circulation in heating systems.
Highly corrosive liquids (acids, alkalis, salts, organic solvents) – high seal requirement
First choice: CQB/ZMD/CQG/ZCQ series magnetic drive pumps and GBF series lined fluoroplastic pipeline pumps. Second choice: IHF/FSB series fluoroplastic centrifugal pumps. When liquid level is below pump installation, FZB/ZMD self‑priming pump must be used. For zero leakage and contamination prevention, magnetic drive with self‑priming is the best partner.
High‑viscosity media (oils, syrups, resins, asphalt) – low head but high resistance
First choice: KCB/2CY/YHCB/NYP/triple‑screw positive displacement pumps. KCB is economical and widely available, suitable for 5-1500 cSt lubricating oil. YHCB is high flow, for terminal offloading. NYP is suitable for semi‑solid materials >5000 cSt. If corrosive, use stainless steel pump body with copper gears and explosion‑proof motor. For extremely high viscosity >30,000 cSt, BBG internal mesh and triple‑screw pumps perform well.
Liquids containing solid particles/fibers – wastewater, sludge, pulp – prone to clogging
First choice: WQ/AS/AV/JYWQ submersible non‑clogging sewage pumps. For large particles or long fibers, use AS (shredding) or JYWQ (automatic mixing); for coal fines/ore slurry, use BQW flameproof submersible pump. For sludge dewatering or high‑viscosity solids‑laden sludge, single‑screw pumps (G/WG) have advantages. For highly abrasive particles (e.g., mill scale), use abrasive‑resistant slurry pumps.
Pump above liquid level, no positive suction head, cannot self‑flood – need self‑priming
Choose FZB self‑priming pump. For strict corrosion resistance, choose ZMD self‑priming magnetic drive pump to avoid leak‑prone foot valves. For strong acid/alkali tanker loading/unloading, PTFE diaphragm pumps are safer.
Flammable/explosive area or no electricity – pneumatic
First choice: QBY pneumatic diaphragm pump (intrinsically safe). Also choose KCB stainless steel gear pump with copper gears and explosion‑proof motor, or ZMD explosion‑proof magnetic self‑priming pump.
Precise dosing – flow must be adjustable and strictly stable
First choice: metering pump (plunger/mechanical diaphragm/hydraulic diaphragm). For RO antiscalant injection, petrochemical catalyst injection, and lime slurry dosing in wastewater plants, hydraulic double‑diaphragm pumps are the first choice. For laboratory micro‑flow (<5 L/h) high‑pressure applications, J type plunger metering pumps can replace G type single‑screw pumps.
High solids, highly abrasive slurries, tailings – erosive and impactive
Prefer UHB‑ZK wear‑resistant slurry pump, lined with ultra‑high molecular weight polyethylene, which has wear resistance many times that of F4 or stainless steel. ZJ/AH slurry pumps with high‑chromium alloy wetted parts are the industrial standard for tailings feed, heavy‑medium cyclone feed, and coal‑washing dense medium suspensions.
8. Practical Selection Guide and Common Mistakes
8.1 Five core data points for pump selection
Before selecting, you must determine: maximum flow, system head (add 5%-10% safety), physical/chemical properties of the medium (temperature, viscosity, corrosiveness, solids content), and piping layout (pipe length, number of elbows, inlet liquid level, suction side pressure, atmospheric pressure difference).
8.2 Three most common selection errors
1. Selecting based solely on maximum head: Some designers focus only on head, ignoring whether the operating point lies in the pump’s high‑efficiency range. This leads to long‑term operation in the high‑flow, low‑head zone, causing motor overload and burnout.
2. Ignoring viscosity: If a high‑viscosity medium is matched with a centrifugal pump instead of a positive displacement pump, hydraulic losses become huge, resulting in near‑zero flow.
3. Neglecting pipe friction and liquid temperature effects: Underestimating total head by tens of meters due to friction losses leads to low flow and cavitation, damaging impellers and bearings.
8.3 How to use pump performance curves to choose the best model
Every pump model should have a flow‑head (Q‑H) curve. The required flow and head must fall within the pump’s high‑efficiency zone. If parameters are not in the table, you can select from curves with different impeller diameters or consider speed reduction. Also, pay attention to the net positive suction head required (NPSHr). The system’s available NPSHa must be greater than NPSHr to avoid cavitation, noise, vibration, and impeller damage.
9. Conclusion
By reviewing all mainstream models of dynamic pumps (centrifugal, axial‑flow, mixed‑flow, submersible), positive displacement pumps (gear, screw, diaphragm, plunger), and special pumps (magnetic drive, canned motor, self‑priming, slurry), it becomes clear that the core of pump selection is: medium properties determine materials (stainless steel / fluoroplastic / cast iron / high‑chromium steel), performance curves determine model, and operating conditions determine pump type. Choosing the right pump type can save significant maintenance costs and allow equipment to last more than ten or even twenty years.
We hope this comprehensive analysis serves as a reference for your design and procurement work. Readers can quickly compare parameter ranges of different pump types and understand the strengths of centrifugal, screw, gear, and other pumps. If you still have uncertainties, consult pump manufacturers’ technical support and have professionals verify the operating point, materials, and seal requirements to ensure safe and reliable final selection.
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