“无密封泵”一词在流体的转移中经常使用。如果您不熟悉该行业，该概念可能会令人困惑。可以通过名称推断出这些泵不使用传统的密封组件，但是该泵到底需要什么，以及哪些类型的应用程序对于没有传统密封的泵来说是理想的选择？
Let’s first review how mechanical centrifugal pumps operate. Mechanical centrifugal pumps have a motor-driven shaft that extends from the motor on the dry end of the pump, to the impeller on the wet end of the pump (the end that is intended to get wet). They utilize a mechanical seal where the shaft enters the wet end, preventing any leaking of the fluid from exiting the wet end casing. The spring-loaded mechanical seal component is built to stay in place around the rotating shaft and maintain fluid separation between system mechanisms.
Mechanical seals are still the preferred method for many applications, specifically applications that move water or other non-hazardous liquids. Pumping water from wells, light chemicals, aquarium filtering, aeration, water cooling, fuel injection, and cooling towers are all ideal applications for mechanical pumps. They are a more affordable option in comparison to sealless pumps and reduce power consumption compared to traditional “gland packing”, the earliest method of pump sealing that packs rope-like material around the shaft to prevent leakage from the wet end.
However, there is a downside to mechanical seals when it comes to hazardous materials. Mechanical seals are friction components that can wear and eventually fail when not properly maintained. In cases where the mechanical seal does fail, leaking fluid to the external environment will occur. This becomes a huge safety issue when dealing with hazardous materials. There are options for double or tandem mechanical seals, but they can significantly raise the price. This is where sealless pumps come into play.
A sealless pump allows for a fully enclosed wet-end of the pump, eliminating the need for any seal at all and eliminating the possibility of material leakage. Instead of a single shaft that runs from the motor all the way through to the impeller, the shaft is actually two separate pieces – one piece driven by the motor on the dry end, and the other piece driving the impeller in the fully enclosed wet end. You might be wondering how the impeller shaft gets rotated when it is not physically attached to the motor, and the answer is magnets.
Before the age of ipads and smart phones, you might remember a childhood toy called a magnetic maze. The object of the game was to get a metal ball through a maze without touching it. To accomplish this, the player used a magnetic pen on the opposite side of the surface to attract the metal ball and guide it through the obstacles. This is the basic concept that applies to sealless pumps and allows the impeller shaft to be rotated within an enclosure.
无密封泵上的叶轮轴封闭在湿端外壳中，并配有磁套。在泵的干端内，电动机轴上有另一个磁性套筒，可在湿端套筒周围。两个袖子被外壳隔开，但是它们之间的磁力非常强，以至于随着较大的袖子被马达轴旋转，它在湿端内也将较小的套筒转动，有效地旋转了湿端轴和叶轮在封闭空间（这就是为什么无密封泵通常也称为“磁性驱动器”泵的原因）。
If you are still having trouble visualizing the concept, this video provides a good illustration of the internal components of sealless pumps:Magnetic Drive Sealless Pumps – YouTube
如前所述，无密封泵非常适合处理有害物质的应用，包括酸，酒精和甘油，碱，卤化物，传热液，碳氢化合物，氮和硫化合物，盐和其他化学物质。在处理这些材料时，必须防止泄漏并为“无密封”或“ MAG驱动器”泵的较高成本辩护。