I have worked with rigid PVC for many years in plumbing
The colour coding is for identification - not for additional odour reasons.
PVC is best material used in chemical fume cupboards.
If you need to bend the rigid PVC - simply use a heat gun. Experiment
first as the heat gun will quickly get the PVC hot and can burn it brown.
Apply the heat evenly around the PVC and very quickly it will be flexible.
When you bend the PVC it can kink. To overcome this find a piece of flexible pipe (rubber or flexible PVC) which has a thick wall.
Use this as a former and you can easily bend the PVC into a U bend with 200 mm radius - and without collapse.
The best PVC pipe to use has thicker wall - although the thicker wall will take longer to heat soak through to the inside wall.
To cool it down - hold in place for a few seconds until it rehardens.
If you do not have a heat gun - then borrow the wifes (girlfriends) hair dryer - it works just as well.
Problems will arise if you overheat the PVC. If you have no browning - you can create all sorts of bends. Make sure you do not have sagging which will allow the fluid to pool.