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High and low temperature explosion-proof all-in-one machine as the most common movement equipment in industrial production, high temperature and low temperature circulating tank used in high temperature and low temperature all-in-one machine and pumps have more and more demanding occasions under the use of higher and higher conditions. Shielded pumps are more and more widely used in chemical plants, because it does not have a shaft seal and can not achieve no leakage. Some people ask, what is the difference between shielded pumps, magnetic pumps and centrifugal pumps? The fully sealed or leak-free construction of shielded pumps makes them most suitable for pumping flammable, precious, corrosive and toxic liquids. Because shielded pumps do not leak, they contribute to the safety of flammable liquid systems:They have significant economic results for expensive corrosive liquids.
The difference between shielded pumps
1. The motor and pump are integrated, and the pump and motor are connected coaxially;
2. The inner side of the motor stator and the outer side of the rotor are equipped with shielding sleeve, and the inner side of the shielding sleeve is connected with the pump;
3. Installation is divided into horizontal and vertical type
4. The motor cancels the cooling fan, and the motor is cooled by the circulating medium between the stator and rotor, using the surface cooling of the motor base.
Advantages of shielded pump
1. Fully enclosed. There is no dynamic seal in the structure, and only static seal in the pump casing, so there is no leakage at all. Particularly suitable for the transport of flammable, explosive, precious liquids and toxic, corrosive, radioactive liquids.
2. High safety. The rotor and stator are respectively equipped with shielding sleeve, so that the rotor and stator of the motor are not in contact with the material, even if the shielding sleeve ruptures, there is no danger of external leakage.
3. Compact structure and small area. The pump and motor are integrated, and no alignment is required for disassembly and assembly. Low requirements for foundation and ground, low routine maintenance workload, low maintenance cost.
4.Smooth running, low noise, no need to add lubricant. Because there is no rolling bearing and motor fan, there is no need to add lubricant and low noise.
5. Wide range of applications. It can meet the requirements of various working conditions such as high temperature, high pressure, low temperature and high melting point.
Disadvantages of shielded pump
1. As the shielded pump adopts sliding bearings, lubricated by the conveyed medium, poor lubrication of the medium should not be conveyed by the shielded pump. Generally applicable to the shielded pump medium viscosity of 0.1 ~ 20 MPa - sec.
2. Shield pump efficiency is usually lower than the single-ended mechanical seal centrifugal pump, but roughly equivalent to the double-ended mechanical seal centrifugal pump.
3. Running for a long time under low flow conditions, the low efficiency of shielded pumps can lead to heat generation and liquid evaporation, resulting in dry rotation of the pump, which can damage the plain bearings.
Comparison
High and low temperature explosion-proof all-in-one machine,Shielded pumps are used in the following situations.

1, the pressure situation is not normal. Used when the pressure on the suction side of the pump is high and the pressure difference on the discharge side is low. If a stuffing box is used, it will be subjected to extra stress.

2. Where high vacuum needs to be maintained. If a stuffing box is used, air will enter through the stuffing box when an important official is slightly off-centre or worn out.

3. Alternate vacuum and pressure operation. Stuffing boxes or sealing structures used for normal vacuum operation cannot be used for pressure operation.

4. Handling of precious liquids. Mobility, resulting in greater economic losses.

5. Handling of toxic liquid. As well as danger to life. If stuffing box is used, a considerable amount of valuable materials will be lost due to leakage every year. If using stuffing box, the leakage of toxic liquid will cause harm to human health.

6、Explosive gas occasions. While flammable liquids, such as petrol, paraffin, jet fuel, etc.. can be transported by connecting centrifugal pumps with rotary seals and explosion-proof motors, leaking liquids and liquids that turn into vapours can make the whole site an explosion-hazardous place.

7. Occasions for handling radioactive liquids. Radioactive liquids are not allowed to leak from stuffing boxes. In addition, many fillers are made of materials that cannot be exposed to radioactive liquids for long periods of time.

8. Handling of corrosive liquids. In addition to the packing box leakage caused by local corrosion, the process unit will be subject to corrosive liquid leakage caused by the erosion of the vapour.

9. Handling of hazardous liquids. When the stuffing box leakage produces a bad odour and other harmful gases, it will form a bad situation in which the operation cannot be carried out.

10. When handling liquids that react easily. If a shielded pump is used, the liquid will not be contaminated by gases, moisture, packing lubricants, etc., and will not solidify, crystallise, etc., causing other obstacles.