What are the respective advantages and disadvantages of the different types of purging compounds?

Abrasive purging compounds can be economical to utilize, and are efficient for certain situations but they can damage worm and cylinders. As well, they are not universally usable, for example they cannot be used in hot runner systems.

Chemical-based purging compound tend to be milder than abrasive purging compounds, making them safer for equipment, they are universally usable in hot runner systems, can be injected in cavity and are economical in use. However, they require a polymer matrix which is not always compatible with other polymers. 

Purging compounds in the concentrate form can, in principle, be mixed with all polymers universally, but they tend to be more expensive, require time-consuming preparation and create the potential for risk of incorrect dosage. In case of concentrated powders there is also the issue of contamination of conveyor systems and dust loading. Ready-to-use purging compounds are easy to use, there is no risk of incorrect dosage, but they require a polymer matrix which is not always compatible with other polymers.