What types of pumps are considered special pumps?

In my opinion, pumps that are designed specifically to transport a certain type of material are special pumps, similar to liquid chlorine pumps

It generally refers to non-centrifugal pumps, such as positive displacement pumps, plunger pumps, and screw pumps

There is currently no unified standard for defining what kind of pumps are special pumps. Generally speaking, special pumps refer to various types of pumps that are designed for transporting specific liquid media, and have special requirements and application scenarios. Such as transporting liquids containing impurities, suspensions, volatile substances, high-viscosity fluids, highly corrosive materials, flammable and explosive substances, radioactive materials, toxic substances, and valuable liquids; as well as in situations where self-priming is required, metering is necessary, or where high temperatures and pressures or low temperatures and pressures apply. Due to the special nature of the liquid medium pumped by the pump, as well as the specific requirements and application scenarios, the performance requirements, structural design, material selection, and operating methods of such pumps are also different from those of ordinary pumps. However, special pumps are essentially developed based on ordinary pumps, and in reality most of them are variations of ordinary pumps.

There is a problem with this question itself. Generalized is too broad.

Special pumps must be at the forefront of technology, right?

It doesn’t seem to be a shielded pump. Nisshiki Seisakusho, Teikoku, Kaimi, and many others – they’re not considered special.