I got two flow lines at 90 degree angle, Line A carrying acid and line B carrying water, each with 1 inch diameter, merging at point P. The third line C beginning at point P, also 1" diameter, should carry 90% water and 10% acid. I came up with option 1 but not sure how to achieve the same using the Option 2 or 3. Option (1) Using two flow meters and two valves. Install two manual valves, one on A line, and another on C line. Install two flow-meters such that each line has one flow-meter but at the upstream of these valves. Now fully open the valve on B line, check the flow-meter reading, and calculate 10% of this flow. Open the valve on A line slowly until the flow-meter reads 10%. (Of course I could do the same on B line). Option (2) Using two pressure gauges and two manual valves. Option (3) Using one pressure gauge and one flow meter with two manual valves. What's the most economic option considering the cost of a pressure gauge being $100 and flow meter being $2000, and the flow resistance being insignificant? Pls explain the procedure. Thanks.