When your radiator "blew up" - what caused that condition? Either - a sudden failure or just old and due to an impact of debris - end result - the radiator leaks.
Sudden failures are related back to pressures within the system. It's a sealed system.
The "purge line" that comes with it, is usually adequate for it's lifetime. It just takes the air pockets it gets when the engine gets hot and the pressure of the coolant gets close to it's boiling point - and bleeds them off into the recovery tank - that's the line you have. If you follow it, it goes from the upper port on the tank, to the top of the exhaust side of the rear 4-cylinder on the cylinder head. People have taken that off, and they have that..."Hey! What's this?" moment There is small piece of plastic/metal to act like a bell - valve. It rests in a notch of that port and has the ability to move, letting air that would have stayed back there, to move out of the coolant and into and up thru that smaller line back out to the recovery tank
The Line I was referring to is on the radiator itself, it has a capped off port that is used for another purpose it once had. Which was similar to the bubble line you have now. The Tank itself also provided that port to take the bubbles that formed in the radiators' upper cap that they felt needed to have to return to the tank to remove the air pockets from that portion of the system.
Since you're changing it, you do not have any support from Ford for that port or the line it once had, unless you dig around in a wreck/junk yard for the older 2008 or so models that uses that "Ztech" engine that Focus and others also used. These designs also circulated fluid from the radiator using that hose all the time. They served to reduce air pockets, but forced a lot of heat from the engine out at the same time due to the unrestricted lines - bypassing the thermostat which helped keep the motor cool, but reduced the efficiency and for those in wither climates - anemically poor heating.
The Coolant tank also got way too hot for safety - so they removed the line and added in that bubble purge line to redice that circulation condition and let the air escape the motor.
So this may mean more of a another condition...
If you have a lot of miles on the motor - the cylinder head to engine block gasket - that seal may be breaking down.
IT starts out as some air that is trapped - bulges the tank, then if too much leaks past the gasket - it can burst the coolant tank and you can lose all your fluid. Ruining the motor - and your day.
The air this line would have - is from the combustion products that leak past the gasket and get into the coolant and the oil.
If left to itself for some time it collects that in the oil as a residue - you'll see a light colored "brown grease" that tells you you have coolant leaks into the oil - caused by the air, into the coolant, and this seeps into the oil - and due to the detergents in both systems, this forms that crud you see on the inside of your oil fill cap.
So, to me, I only mentioned that "History" because people have pulled off that cap and found out that they made a mess, this also can put you in a world of hurt for that port has a lot of hot fluid behind it - and when it worked - that pushed a lot of hot coolant back into the recovery tank making it a little too hot to handle.