Pipeline unsteady flow measuring point should which item to pay attention to

The following are likely not steady, cautious selection of measuring point.

1 measuring point distance pump outlet, half open valve pipe can not guarantee 10D, and no elbow buffer device.

2 measuring point distance pump outlet, half open valve pipe can not guarantee 10D, high flow speed.

3 vertical downward flow, oblique flow.

4 measuring points downstream piping open, and straight pipe section is less than 10D.