Chemical pumps are used in the petrochemical, food processing and chemical industries, as well as in off-site refinery applications and high-temperature heating systems. They pump hot, cold, aggressive, volatile, explosive, toxic, contaminated and especially high-value fluids.
For this reason, parts in contact with the fluid are made of corrosion-resistant metallic and non-metallic materials, or are protected with durable rubber, plastic or enamel coatings.
In this pump, the casing has been given a plastic coating to protect it from the corrosive effects of the fluid.
Both single and double mechanical seals can be used in chemical pumps. In some cases, a thermosiphon system independent of the pump is used to pressurize the seal chamber or provide external flushing. As noted above, the fluids pumped by chemical pumps are generally high-value, explosive, or harmful to the environment and human health. For this reason, the issue of seal tightness is extremely important. If zero leakage is required, a canned motor pump or magnetically coupled pump is used instead.
Magnetically coupled pumps are sealed from the outside, except for the suction and discharge flanges. The shaft is driven by magnetic field force. For this reason, they are frequently preferred where zero leakage is required.
Chemical pumps are generally designed as single-stage, and rarely as two-stage. They are usually not self-priming. For pump selection, it is important for the pump to have as low an NPSH value as possible. To meet special operating conditions, design variants are used that feature heatable casings, coolable bearing housings, and external support systems (such as a thermosiphon system or a heating/cooling jacket).
Source: KSB Global
