Ryan,
Some modelers use urethanes on model cars as they produce a beautiful color that no other paints can match.
They are the main paint being used these days in custom automotive paint jobs and airbrushing also.
Rick,
If you spray a lot of lacquer thinner through it when finished then you do not have to take it apart, but it has to be clean or those urethanes will dry inside and that is not pretty. Spray lacquer through it quite a bit, and backflush it also a time or two.
Then spray some more clean thinner through it and it should be fine.
If you want you can take it apart if it makes you feel better knowing it is really clean but it isn't necessary if you just spray it out good.
I use higher pressure when I spray out also and prefer 50 psi or so, but if your compressor doesn't go that high then use the highest pressure you can.
Mike
“Wisdom is the right use of knowledge. To know is not
to be wise. Many men know a great deal, and are all the greater fools
for it. There is no fool so great a fool as a knowing fool. But to know
how to use knowledge is to have wisdom. " Charles Spurgeon