Part DP is normally inserted into Type B, C & D adapters of the identical size. Black polypropylene is extensively used in chemical industry, agriculture and paints & inks factory. It is not only because of its good performance in resisting chemicals, coolants and treated waters, but also cheap price and simple operation.
As to chemical resistance, polypropylene cam & groove couplings do well as stainless steel coupling. However, it is not so strong and durable. So, it should be taken carefully when you install or release the coupling. DP adapter should not be worked under pressure.