Connecting 6 inch to 4 inch PVC

[emptybucketman]

I see that there is a 150mm to 100mm level invert taper pvc fitting to connect a 6 inch and 4 inch pvc pipe. How should the fitting be oriented or doesn't it matter? See option A and B attached.

[DavidG]

What is in the pipe and what is the direction of flow?

Smooth bottom seems to be the logical answer.

[Yonnee]

Flow right to left, either will work.

Flow left to right, only the bottom will work anyway.

[bricks]

The top of the pipe should be level and the step should be at the bottom. ( if your using it on sewer drainage.)

If your using it on storm water it dont matter.

This is because some one ( not me) thinks that rising sewr gasses may be caught in the top of a non level section and erode the glued joint. ( or so im told.) But it is also in the plumbing code that the top of the pipe remains level.

[emptybucketman]

The pipes are for sewer drainage and the flow is from right to left.

Bricks...do you know the specific clause?