In industrial production, handling corrosive fluids is a common and challenging task. Choosing the right pump is essential to ensure smooth production processes, safe operation of equipment, and safety of personnel. Next, let’s take a closer look at how to select the right pump for corrosive fluids.
What are the Corrosive fluids
Corrosive fluids are a class of corrosive liquids. They can react chemically with the materials they come into contact with. This causes damage to the material and degradation of its performance.
Sulfuric acid (H₂SO₄) and hydrochloric acid (HCl) are typical corrosive fluids. Sulfuric acid is widely used in industry. But it is highly oxidizing and corrosive. It can react with many metals and non-metallic materials. Hydrochloric acid is an aqueous solution of hydrogen chloride with a pungent odor. It is also highly corrosive to materials such as metals.
In industrial production, once these corrosive fluids come into contact with unsuitable materials. It may cause equipment failure, leakage, and other problems. Not only does it affect production efficiency, it may also pose a threat to the environment and personnel safety.
Pumping Corrosive Chemicals: Sulfuric and Hydrochloric Acid
a. Sulfuric Acid Pumps
Sulfuric acid is widely used in the industrial field. Industries such as chemical manufacturing, mining, and petroleum refining cannot do without it.
In chemical manufacturing, nearly 50% of global sulfuric acid is used to produce phosphate fertilizers; in the mining industry, sulfuric acid is used to extract metals from ores.
Since sulfuric acid is highly corrosive, it has high requirements for pump materials. If the concentration of sulfuric acid exceeds 95%, it can convert the carbon commonly used as a bushing in the pump into carbon dioxide. When the concentration is higher than 70%, nitrile rubber commonly used as a pump O-ring cannot resist its corrosion.
For the selection of sulfuric acid pumps, at room temperature, it is recommended to use a centrifugal sealless magnetic drive pump made of polypropylene or polyvinylidene fluoride plastic. Then match it with Viton O-rings, carbon or mica polytetrafluoroethylene bushings. Fluoroplastic magnetic drive pumps and magnetic self-priming pumps such as South Pump are good choices.
b. Hydrochloric Acid Pumps
Hydrochloric acid also plays an important role in many industries. For example, steel pickling, oil well acidizing, food industry, leather manufacturing, and PVC material production.
In steel pickling, hydrochloric acid is used to remove scale and rust from the surface of steel. In the food industry, it can be used to produce high fructose corn syrup, etc.
Due to the strong corrosiveness of hydrochloric acid, choosing the right pump is crucial. For pumping hydrochloric acid at room temperature, it is recommended to use a centrifugal, sealless magnetic drive pump made of polypropylene or Kynar plastic. Equipped with a sealed impeller and carbon or mica PTFE bushings. South Pump offers a variety of pump models suitable for hydrochloric acid delivery, with flow rates ranging from 3m³/h-800m³/h, such as high temperature stainless steel magnetic pump, etc.
Managing Fluid Viscosity: From Water to Honey
a. Low-Viscosity Fluids
Low viscosity fluids, such as water, milk, beer and olive oil, have good fluidity and less resistance when flowing in pipes. Centrifugal pumps are a more suitable choice for pumping low viscosity fluids.
The working principle of a centrifugal pump is to rely on the high-speed rotation of the impeller. The fluid is subjected to centrifugal force and is thrown out. Since low viscosity fluids have little effect on the performance of centrifugal pumps, even if the fluid viscosity changes slightly, the chemical centrifugal pump can still maintain a good working condition.
However, when the liquid is slightly thicker than water, the performance of the centrifugal pump may decline. At the same time, power consumption will increase.
b. High-Viscosity Fluids
High viscosity fluids, such as honey, syrup, peanut butter and some oils, have poor fluidity, move slowly and are not easy to deform. When pumping high viscosity fluids, positive displacement pumps are the first choice, such as gear pumps, diaphragm pumps, vane pumps and hose pumps.
These pumps transport fluids by periodically changing the volume of the pump chamber. They can operate at lower speeds and adapt to the viscosity of the fluid by adjusting the flow rate. In addition, peristaltic pumps can also effectively handle high-viscosity products. They can run dry without causing damage to the pump. The flow rate is proportional to the speed, which is suitable for applications that require precise and repeated metering.
When pumping high-viscosity products, it is also necessary to ensure that there is no obstruction on the suction side and use submerged suction. And it may be necessary to increase the size of the system pipeline to reduce resistance losses.
Key Considerations for Pump Selection
a. Fluid properties
When selecting a pump, you must fully understand the various properties of the fluid. In addition to corrosiveness and viscosity, you must also consider the fluid’s temperature, concentration, specific gravity, whether it contains particulate impurities, etc.
Fluids with different properties have different requirements for the pump’s material, sealing method, impeller design, etc. For example, fluids containing particulate impurities may wear the internal parts of the pump. It is necessary to select a pump with wear resistance and the corresponding material.
b. Pump material
The material of the pump is directly related to its corrosion resistance. For highly corrosive fluids, avoid using easily corroded metal materials such as aluminum and cast iron. You can choose corrosion-resistant metals such as alloys and titanium, or high-performance plastics such as polypropylene and Kynar.
At the same time, the materials of the pump’s sealing materials, O-rings, bushings and other components must also match the fluid properties to prevent leakage and corrosion.
c. Working environment
The working environment is also a factor that cannot be ignored when selecting. If used in a flammable and explosive environment, a pump with explosion-proof function should be selected. In high or low temperature environments, the material and seals of the pump need to be able to adapt to the corresponding temperature range.
In addition, practical factors such as space limitations and installation conditions must also be considered. Ensure that the pump can be installed and operated smoothly.
d. Flow and head requirements
According to actual production needs, it is crucial to accurately determine the flow and head of the pump. The flow determines the amount of fluid pumped per unit time. The head indicates the height to which the pump can lift the fluid or the ability to overcome pipeline resistance.
If the flow and head of the pump are not selected properly, it may lead to low production efficiency or the pump cannot work properly.
Conclusion
Selecting a pump suitable for corrosive fluids requires comprehensive consideration of many factors. Whether it is corrosive chemicals such as sulfuric acid and hydrochloric acid, or fluids of different viscosities, there are pump types that match them.
In the actual selection process, it is necessary to fully understand the fluid characteristics, working environment and other requirements. Combine the material, flow rate, head and other parameters of the pump to make a selection.
When encountering complex situations, consult professional pump manufacturers or dealers in time. It can help us make more appropriate decisions and ensure that the production process is carried out safely and efficiently.
