Related Legal Terms & Definitions. 1  COMPETENT WITNESS One who is legally qualified to be heard to testify in a cause. 2  RESPECTABLE WITNESS One who is competent to testify in a court of justice. 3  CREDIBLE WITNESS A credible witness is one who is competent to give evidence, and is worthy ofâ¦.
In general, combustibility of polymers depends on their chemical structures. Polymers with more carbon atoms in their macromolecular structure (e.g., PE, PP, PS, PMMA) are more combustible than polymers containing halogen atoms (e.g., PVC, PVDC, PTFE).
PVC is a rigid plastic pipe made of polyvinyl chloride; it can be used with cold but not hot water, and for residential use PVC is primarily installed as drain/sewer or irrigation/sprinkler pipes rather than as an incoming water distribution system.VC is a rigid plastic pipe made of polyvinyl chloride; it can be used with cold but not hot water, and for residential use PVC is primarily installed as drain/sewer or irrigation/sprinkler pipes rather than as an incoming water distribution system.