Can you guys please take a look at my ladder logic and let me know I'm right or wrong

Hi all, I'm new to PLC programming and PID loops and I'm trying to write the ladder logic for the following process:
"Air is fed from the compressor to the chamber. The pipeline connecting the compressor to the chamber has a flowmeter and two control valves (the pipe splits into two and two control valves are installed on the two pipes to the chamber).I have to control the flow rate of air. The Low Air is opened first and air is fed to the chamber (the flow rate should be around 2-3 scfm). Then after achieving that flow rate we ignite the flame in combustion chamber . once the flame is detected we open Large Air valve and ramp up the flow rate to say 750 SCFM (if I want a total flow rate of 750 SCFM) keeping the Low Air valve opened."
One of my friends gave me the suggestion "Use one PID for smaller valve at startup to get needed flow keep larger valve PID at manual and 0% at this point. When you get ignition and flame is detected set smaller valve PID to manual and 100% (dont know how flame handles this, so might need ramp) and enable larger valve PID." I have written the PLC program for what he said but not sure whether my ladder logic is right or wrong..can you guys take a look at it and let me know...Please

Thank you,

Ding

"...once the flame is detected we open Large Air valve and ramp up the flow rate to say 750 SCFM (if I want a total flow rate of 750 SCFM) keeping the Low Air valve opened."

If you must follow this description STRICTLY, then you must SUBTRACT the Low Air Flow from the Total (750 scfm), and then set the Large Air Valve Flow Rate to be: Large Air Flow Setpoint = (750 - Low Air Flow).