Iron pipework, freeze or flood?

Im going to a job tomorrow which i have to fit a new rad on a system that is iron pipe, i have got a rad the same size but they want new valves. I dont want to drain down and spend all day filling up & getting rid of the air, if i put plugs over the expansion & in the header tank and got my towels out and flippers on do you think i could undo the valves (threaded) and work on them without flooding the place out. I dont really like freezing iron, and it is on the ground floor in the toilets so shall i go for it or not, any past experiance as i never get jobs on iron. thanks

Found iron freezes just as easy as copper. could try bunging it and open the valve to see how wet your going to get.

Have frozen iron before, wet some kitchen wipe and wrap it round the pipe, then attach pipeclamps to freeze with electric kit, u can bung it though close all aavs, change one side at a time, just hope your existing threads are ok.

Thanks lads, i appreciate your help,does iron freeze ok, as i say ive never had to do this before