Final answer:
EPA no longer recommends dry-cleaning solvents and fire extinguishers for cleanup after a burnout; instead, chemical neutralization is a preferred method.
Step-by-step explanation:
According to EPA regulations, the procedure that is not an approved technique for system cleanup after a burnout is using dry-cleaning solvent and fire extinguishers. Originally, these methods might have been in use, but they are no longer recommended because they could leave harmful residues or by-products that can degrade system performance or pose environmental concerns. More contemporary and acceptable practices include using chemical neutralization to mitigate damage to the environment, while specialized fire extinguisher systems or foaming plastics are meant for other purposes but not specifically approved for system cleanup after a burnout.