I want to use a orifice for measurement of flow I have very little margin in the horizontal line. can i use it in the vertical line?

 

Yes, you can be used orifice type flow meter in vertical line. But the condition is that you have a margin on both sides

 

In general the answer is yes but the performance would highly depend on the flow direction i.e. whether the flow is from top to bottom or in reverse direction. The process has to be clean else within no time the orifice plate will collect all the deposition to create measurement errors. It will also depend on the service on which being proposed.

 

yes but always follow the required pipe straight run