A Deep Dive into Micro Pump Sealing Technology | How TOPSFLO Chooses Rubber Seals

In both precision industrial and consumer devices, water pumps play an indispensable role, silently driving the flow of liquids. At the heart of this “engine,” lies a seemingly small yet crucial component — the sealing ring. As the primary sealing element in micro pumps, the sealing ring safeguards each stable operation with the unique charm of its material. Today, let’s delve into the world of micro pump sealing materials and uncover the secrets behind these smart material choices.

Micro pump sealing materials come in a wide variety, each with its own distinct characteristics and applications. In this article, we’ll explore the common rubber-based materials used in sealing elements.

Nitrile Butadiene Rubber （NBR）

NBR?is a type of synthetic rubber copolymerized from acrylonitrile (ACN) and butadiene, primarily produced through a low-temperature emulsion polymerization process. The specific gravity of NBR?is 1.5 ± 0.05g/cm3, with a tensile strength of ≥500 PSI or 3.5 MPa, an elongation of ≥350%, and a hardness of 65° ± 5° shore A.

NBR can have five different acrylonitrile (ACN) content percentages: 42-46%, 36-41%, 31-35%, 25-30%, and 18-24%. The higher the acrylonitrile content, the better the oil resistance, but the cold resistance decreases correspondingly. Besides its excellent oil resistance, NBR also possesses good abrasion resistance and aging resistance. Additionally, it has good gas tightness, effectively preventing the leakage of oil media and enduring the friction and wear during the operation of water pumps. It is often used in micro water pumps that need to transport oil media.

Advantages

1. Excellent Oil Resistance: Nitrile rubber exhibits outstanding resistance to various oils, fuels, and solvents, making it ideal for applications requiring protection against water or oil.

2. High Wear Resistance: It effectively reduces the wear rate of sealing components, thereby extending the lifespan of the seals.

3. Good Heat Resistance: Nitrile rubber maintains the stability of its physical and chemical properties even at high temperatures.

4. Excellent Processability: Nitrile rubber seals are easy to mold, extrude, and inject, offering high production efficiency and relatively low costs, providing a great balance of performance and value.

Ethylene-Propylene-Diene Monomer（EPDM）

Ethylene-Propylene-Diene Monomer (EPDM) is a copolymer of ethylene, propylene, and a small amount of non-conjugated diene, primarily produced through processes such as solution polymerization and suspension polymerization. Commercial production of this material began in the 1960s. Annually, the global consumption of EPDM is 800,000 tons.

The most prominent characteristic of EPDM is its superior resistance to oxidation, ozone, and corrosion. As EPDM belongs to the polyolefin (PO) family, it exhibits excellent vulcanization properties. Among all rubbers, EPDM has the lowest specific gravity and can absorb a large amount of fillers and oils without significantly affecting its properties, thus allowing for the production of cost-effective rubber compounds.

Advantages

1. Extremely high chemical stability: The main chain of EPDM rubber is composed of chemically stable saturated hydrocarbons, with unsaturated double bonds only in the side chains. This structure grants EPDM rubber extremely high chemical stability, enabling it to resist heat, light, oxygen, and especially ozone erosion.

2. Excellent aging resistance: Due to the saturation of its main chain, EPDM rubber exhibits outstanding aging resistance, including weather resistance, ozone resistance, sunlight resistance, heat resistance, water resistance, water vapor resistance, UV resistance, and radiation resistance. When used in combination with other unsaturated diene rubbers such as NR, SBR, BR, NBR, and CR, EPDM can function as a polymer antioxidant or antidegradant.

3. Cost-effective: EPDM rubber has a relatively low density, typically ranging from 0.860 to 0.870, making it the lightest commonly used rubber in terms of raw rubber density. This results in lighter products, which helps reduce costs. The raw rubber density is only 0.86 to 0.90g/cm3, and it can be filled with a large amount of material to reduce the cost of the rubber compound.

4. Excellent electrical insulation properties, with a volume resistivity of 1016Q·cm, a breakdown voltage of 30 to 40 MV/m, and a dielectric constant (at 1 kHz, 20°C) of 2.27.

In micro pumps, EPDM rubber is commonly used for sealing components in cooling fluid and water systems, as it maintains stability and durability under various environmental conditions.

Fluorinated Rubber（FKM）

FKM?refers to a synthetic polymer elastomer containing fluorine atoms on the carbon atoms of its main chain or side chains. It is an irreplaceable key material in cutting-edge national defense industries. Since 1943, various types of fluorinated rubbers have been developed, including polyolefin-based fluorinated rubber, nitroso fluorinated rubber, tetrapropyl fluorinated rubber, phosphazene fluorinated rubber, and perfluoroether rubber.

The introduction of fluorine atoms provides the rubber with excellent heat resistance, antioxidant properties, oil resistance, corrosion resistance, and atmospheric aging resistance. It has been widely used in aerospace, aviation, automotive, petroleum, household appliances, and other fields.

Advantages:

1. Excellent Chemical Resistance: FKM seals are highly resistant to a wide range of corrosive liquids and gases, including oils, fuels, acids, and solvents.

2. High Temperature Stability: FKM seals are designed to withstand temperatures ranging from -40°C to 240°C.

3. Outstanding Resilience: They ensure long-term stable sealing performance, reducing the risk of leaks.

4. Good Mechanical Properties: FKM seals maintain sealing integrity even under harsh conditions, such as high pressure, vibration, and mechanical stress.

5. Wide Compatibility: FKM seals are compatible with a variety of fluids, including mineral oils, hydraulic oils, fuels, and chemicals.

6. Additional Features: FKM seals also offer excellent oil resistance, ozone resistance, strong resistance to permanent compression deformation, and high wear resistance.

Besides the rubber materials introduced above, there are also hydrogenated nitrile rubber (HNBR), silicone rubber (Q), fluorosilicone rubber (FVMQ), tetrapropylene fluorinated rubber (TFE/P), and perfluoro(ether) rubber (FFKM).

TOPSFLO?adopts high-quality imported rubber materials, primarily EPDM rubber, which boasts high purity, excellent abrasion resistance, and the ability to withstand frequent startups and prolonged continuous operation. We can select the most suitable rubber components based on the type of liquid, such as NBR, FKM, or FFKM.