Thank you Paul, I'll see what I can do with this code. It should be enough to figure some stuff out.

excelledsoftware: There are certain formulas that I'll be using to convert but I can just insert them into code easily.

The hard part is that the cell contains more that one set of numbers and I would like to convert both sets. If you look at the attached excel sheet from my first post you can see that I have 233 GPM @ 65'. So I would be converting GPM (gallon per minute) to CMH (cubic meters per hour) and convert the 65 feet to meters. Also The GPM will fluctuate quite often and have different amount of digits if that makes sense.
The right side of the cell will never change, the only thing that will change are the numbers, so my thought was to use something like this
or like this
But I can't get the previous code to work either.

I'll also be converting from inches to mm, in the text a " symbol is used for inches, so I would search for " and convert the number to mm, sometimes there are two " lengths in the same cell that I would convert

I would also like to add parenthesis to the original text (look at my attached sheet for clarification

This is a lot to do and I'm just starting out so it might take me a little bit. I am happy to hear that it is possible. Thanks for your help. Let me know if I can clear things up.