The magnetic drive pumps and shield pump comparison
In the past ten years, magnetic drive pumps have become the common equipment used in many fields. In contrast, shield pump has been regarded as a kind of pump that price is higher and more special, it is only design and manufacture only when special order in cases. Although this view is changing with standardized shield pump series appearance, but canned motor pump is still occupy quite small share in the market.
Generally speaking, the reliability of non-sealing pump is equal to or better than sealed pump. But these two pumps will be damaged by improper using (especially dry turn and operate deviate from design point). Use conveyance medium lubrication bearing no sealing pump after long time dry rotation occurs bearing wear. Under the absence of running monitoring cases, this wear is invisible, in some cases can lead to pump damage and seal sleeve ruptures. Standard magnetic-driving device under the damage situation will make liquid entering into coupling, and through coupling bearing leaks into outside atmosphere. This leakage is often limited due to liquid must flow through twists pathways, general won't cause serious consequence. The standard magnetic-driving devices can also be improved to avoid leak, improvement method is adopting ventage to prevent coupling body pressure increase and adopting auxiliary (driving devices) shaft seal to prevent leakage. In contrast, canned motor pump can make leakage in motor liquid sealing body, and prevent further disclosure. But to seal liquid, only is possible when keeping rigor attention noticed pressure tank (motor shell) to terminal box cable joint. This site is its only weakness. Bad design will make the second part (refers to electric cabinet) with no sealing effect. Even if damaged, magnetic drive pumps can be completely clear, and not damaged parts can be reused. If necessary, the maintenance can be taken at the scene. And leakage into shielding pump motors fluid can make winding damage. Although some pump type has removable stator structure, but most canned motor pump are using sealing type motor or with welding structure, it needs to be sent to the factory to repair or to replace a costly body parts.
To standard magnetic drive pumps, do not need approval dangerous use area, while canned motor pump requires certificate. In many cases this certificate is also different in European countries, it may require additional operation condition monitoring device, such as, need to ensure that the flow liquid storage level detectors. To standard form shielding pump, its temperature limits within 100 ℃. Deciding factor is the motor insulation class, in order to overcome this problem, motor equips with independent cooling circuit, thus increasing the pipeline, cooling fluid source, pumps and heat exchangers additional fees. Standard synchronous magnetic drive pumps can be operated under 400 ℃ temperature.
Overall, magnetic drive pumps can satisfy no sealing pump 90% of all applications. This pump technology specification is complete, economic price, shortest time, easy usage, when maintenance don't need electrician participation, and can direct exchange with ordinary sealed pump. Canned motor pump structure is complex, the price is expensive and usually cannot satisfy the conventional standards. In addition, sealing parts involved maintenance problems, more work installation problem, and the long delivery time, that has made canned motor pump only to be used in magnetic drive pumps that can't satisfy, dangerous degree very high various edge applicable area. Easy to see that these two kinds of pump simultaneously occupy the market, but magnetic drive pumps will occupy a bigger share in the market, and become the main equipment in the future of various environmental, safety industry.
At home, because people's awareness of environmental protection is not very strong, environmental protection laws and regulations also is insufficient, plus enforcement is also not enough, people pay insufficient universal attention to pump leakage problems. Makes China pump manufacturers on how to minimize pump (especially for industrial use pump) leakage research rarely. Cause homebred no sealing pump (including magnetic drive pumps and canned motor pump) research and development level has a large gap compared with advanced international level. With China's accession to WTO, as well as recent five years gives priority to the development of environmental protection industry strategic policy puts forward, can foresee, vigorously develop no sealing pump, will be a development trend in the future of China's industrial pumps.
