To the best of my knowledge, clear is used for PVC electrical conduit and
central vacuum lines, grey is used for underground PVC sewer pipes, and
since we do not use PVC here for drain, waste and vent lines, it or possibly
another flavor of cement may be used for them in areas that mandate PVC DWV
piping. I think they all work in a similar manner.

"z" wrote in message
ups.com...
OK, can anyone explain why Home Depot has like 7 different kinds of PVC
pipe cement, all made by the same company, without a good explanation
of what the differences are? TIA.