shielded pump

It depends on what type of medium you are using, as well as whether your pipes are clean. In my case, the pipes weren’t very clean, and welding slag got into the magnetic pump, causing damage to it that made it unrepairable. If the head requirement is not high, I still recommend using a canned motor pump, as its power consumption will also be lower

This situation is determined based on the properties of the material

Shielded pumps and magnetic drive pumps each have their own advantages and disadvantages. Magnetic drive pumps are generally used in industries such as food processing and fine chemicals, where strict requirements are placed on the medium used. Advantages and disadvantages of shielded pumps: 2.1 Advantages of shielded pumps (1) Fully enclosed design. There are no dynamic seals in the structure; only static seals are present at the pump’s casing, which enables complete leak prevention. This makes it particularly suitable for transporting flammable, explosive, valuable liquids, as well as toxic, corrosive, and radioactive liquids. (2) High safety. Both the rotor and the stator are equipped with shielding sleeves to prevent them from coming into contact with the material; even if these shielding sleeves are damaged, there is no risk of external leakage. (3) Compact structure with low floor area. The pump and motor are integrated; no centering is required for disassembly or assembly. It has low requirements for the base and foundation, requires little routine maintenance, and results in low maintenance costs. (4) It operates smoothly, produces low noise, and requires no lubricating oil. Since there are no rolling bearings or motor fans, no lubricant is required, and it produces low noise. (5) Wide range of applications. It can meet the requirements for various operating conditions such as high temperature, high pressure, low temperature, and high melting point. 2.2 Disadvantages of shielded pumps (1) Since shielded pumps use sliding bearings and are lubricated by the medium being transported, media with poor lubricity are not suitable for transportation using shielded pumps. Generally, the viscosity suitable for the medium in shielded pumps is 0.1 to 20 mPa·s. (2) The efficiency of shielded pumps is usually lower than that of centrifugal pumps with single-end mechanical seals, but it is roughly comparable to that of centrifugal pumps with double-end mechanical seals. (3) Operating for long periods at low flow rates results in lower efficiency of the shielded pump, which leads to heating and liquid evaporation, causing the pump to run dry and thus damaging the sliding bearings. 3 Types and application ranges of canned pumps Based on factors such as the temperature, pressure, viscosity of the liquid being transported, and the presence of particles, canned pumps can be classified into the following types: (1) Basic type: The temperature of the medium being transported does not exceed 120°C, and the head does not exceed 150 m. All other types of shielded pumps can be obtained by modifying and improving the basic model. (2) Reverse circulation type: In this type of shielded pump, the flow direction of the liquid used for bearing lubrication, cooling, and motor cooling is exactly the opposite of that in the basic type. Its main feature is that it is less prone to cavitation, making it particularly suitable for transporting liquids that are easy to vaporize, such as liquefied petroleum gas and chloromethane. (3) High-temperature type: The maximum temperature of the medium being transported is generally 350°C, the maximum flow rate is 300 m3/h, and the maximum head is 115 m. It is suitable for high-temperature liquids such as heat transfer oils and hot water. (4) High-melting-point type: The pump and motor are equipped with jackets, which significantly improves the heat resistance of the motor. Suitable for high-melting-point liquids, with a maximum temperature of up to 250°C. Steam or a liquid at a certain temperature can be introduced into the jacket to prevent crystallization of liquids with high melting points. (5) High-pressure type: The casing of a high-pressure type shielded pump is a high-pressure vessel, enabling the pump to withstand very high system pressures. To support the shield casing under internal high pressure, the stator coils can be used to bear the pressure. (6) Self-priming type: When the suction pipe is not filled with liquid, the pump drains the fluid through automatic air extraction, making it suitable for extracting liquid from underground containers. (7) Multi-stage type: Equipped with multiple impellers, suitable for high-head fluid transport, with a maximum head of up to 400 m. (8) Slurry type: Suitable for transporting liquids mixed with a large amount of slurry. 4 Precautions for selecting shielded pumps: Generally, shielded pumps use a portion of the liquid being transported to cool the motor, and since the gap between the components is very small, the liquid must be clean. When transporting mixtures of various liquids that may produce precipitates, coking, or gels, using a shielded pump (that is not of the slurry type) can lead to blockage of the shielding gap, affecting the pump’s cooling and lubrication and potentially causing damage to the graphite bearings and motor. Shielded pumps generally come equipped with circulation cooling tubes; when the ambient temperature is below the freezing point of the liquid being pumped, anti-freezing measures such as insulation sleeves should be used to ensure easy pump startup. Additionally, when starting a shielded pump, it is essential to strictly follow the correct sequence for opening the outlet valve and the inlet valve. When shutting down the pump, first reduce the opening of the outlet valve; once the pump has stopped running, close the inlet valve first and then the outlet valve. In summary, the use of shielded pumps ensures complete leaklessness, effectively preventing environmental pollution and material loss. As long as the right model is selected and the operating conditions remain stable, there is little need for maintenance during normal operation. Shielded pumps are the ideal choice for transporting flammable, explosive, corrosive, and valuable liquids

To prevent leaks of hazardous materials, shielded pumps or magnetic pumps can be used, but it is a prerequisite that they contain no particulate impurities. Although both options eliminate the need for mechanical seals, they shift the problem to the bearings, resulting in a **reduced lifespan** of the ball bearings. Furthermore, if there are particles in the magnetic pump, they can wear through the isolation sleeve, leading to pump failure; this is extremely dangerous and unpredictable! Reliability is not high. Also, their efficiency is lower than that of centrifugal pumps. Nothing is perfect; a choice must be made based on the specific operating conditions.

As a supplementary note, from a maintenance perspective, magnetic pumps are more convenient

It depends on the specific circumstances. The two types of pumps have many similarities: they are both leak-free and eliminate the problem of shaft seals, but they still present the issue of bearings and have a short lifespan. If the medium contains trace particles, I personally recommend using a shielded pump. There is a slurry-type shielded pump that has less stringent requirements regarding the medium. This post was last edited by zhanong on 2009-3-12 18:14]

The type of chemical pump should be selected based on the properties of the material being handled; for media with high corrosivity, magnetic drive pumps are often used, as this helps to reduce corrosion of components such as the pump’s seals； Shielded pumps are often used for flammable, explosive, and toxic media, as they can prevent leaks.

What are the advantages of magnetic drive pumps over shielded pumps in terms of usage?

The similarity is that both types of pumps are leak-free pumps that do not require lubricating oil, and they are suitable for use in situations where the materials are relatively clean, as well as in toxic or hazardous environments. Maintenance is relatively convenient. Bearings are generally made of silicon carbide or activated graphite. In comparison, shielded pumps are used more frequently, with most of them being produced by Dalian Empire Pump and Shanghai Nikkiso Pump Factory. Magnetic pumps are often used in acidic and alkaline environments. :victory:

It depends on what medium you are transporting. If you have any questions, call 13901683559 or 021-56091698, or contact QQ540992489

Magnetic pump is suitable for industries such as petroleum, chemicals, pharmaceuticals, electroplating, environmental protection, food processing, film and photography, water treatment, and defense. It is an ideal device for transporting flammable, explosive, volatile, toxic, rare and valuable liquids, as well as various corrosive fluids. It can be used to transport liquids with an inlet pressure not exceeding 0.2 Mpa, a maximum operating pressure of 1.6 Mpa, and a temperature not higher than 80°C. A liquid that contains no hard particles or fibers, and no magnetic substances, with a density of not more than 1600 kg/m3 and a viscosity of not more than 30×10-6 m2/s. A shielded pump is a type of water pump with an integrated motor and pump body; it features only a static seal (rather than a rotating shaft seal), which enables complete leak-free operation. Thanks to its low noise level, the motor’s own advantages, as well as the shielded pump’s low failure rate, high reliability, and low maintenance costs, it has won the favor of many users, thereby increasing the demand for high-quality water pumps in the Chinese market. It is widely used in the petroleum and chemical industries, pharmaceuticals, textiles, nuclear power, military industry, as well as in urban water supply and drainage systems, for fire suppression purposes, to provide pressure for water supply in high-rise buildings, for garden sprinkling systems, and in HVAC systems, for the pressurization of hot and cold water circulation. Especially in places with high requirements for vibration and noise, such as key projects, pump rooms, central air conditioning systems, and so on. It can also be used to transport liquids for which pressure and temperature do not cause crystallization or solidification, especially those that are harmful to humans and the environment as well as unsafe liquids and valuable liquids, such as highly corrosive, highly toxic, volatile, radioactive substances.

Additionally, when starting a shielded pump, it is essential to strictly follow the correct sequence for opening the outlet valve and the inlet valve. When shutting down the pump, first reduce the opening of the outlet valve; once the pump has stopped running, close the inlet valve first and then the outlet valve. It seems there’s no such rule; its operation for starting and stopping is the same as that of ordinary centrifugal pumps – it just has an additional step of repeated exhaust

The biggest advantage is leaklessness; no mechanical seal is required, provided the material is clean and has good lubricating properties. Materials with particles cannot be used, as their bearings are located within the medium, leading to rapid wear. Its efficiency is lower than that of centrifugal pumps; therefore, it should be avoided as much as possible for media that are not particularly critical or hazardous.

Shielded pumps are leak-free pumps that are suitable for transporting high-temperature and hazardous substances; their drawback is that their efficiency is only around 80%