74L, that ES was responding to.
SWIP's advice is to scrap the plastic pipe and use a short peice of copper pipe if you can't get glass. Although the temperatures should not be high enough to melt plastic, especially if you use CPVC, the solvents will be pretty hard on it and you might end up with residue in your product.
Heating to 250 F is pretty conservative, especially if you're measuring the temperature on the outside of the heating flask. That equates to ~121 C, which is only three degrees higher than the melting point. If you can get the FB to vaporize at that temperature great, it's good to keep the temperature as low as possible. It's not unusual to need to repeat the process several times to get through a batch, or at least that's been SWIPs experience. Between each scrape the bottom of the flask and break up the FB that has melted together. It often begins to seperate into areas that are tinged with yellow and others that are not. As long as you're going to cook it again you can ignore that and just grind it all up to powder.
SWIM recently tried ES's procedure, although because he wanted FB as the final product, instead of condensing the SPD vapors into another solvent he put the receiver in an ice bath. He then installed another tube into the receiver and connected it to a second receiver which was also in an ice bath, then applied heat to the FB and activated a pump. The second receiver was insurance in case all the FB didn't condense into the first receiver, but it did not work well. The second receiver had an exit tube for safety--didn't want to build up pressure that couldn't somehow be released--but the smell of the air exiting this tube told SWIP that it wasn't only air escaping. Therefore he went back to his original method using a coldfinger test tube in a flask, which has always worked fine with the quantities he processes. For the record, he has no doubt that condensing the vapors into a sovent with a high affinity for them, like xylene, for example, would work much better. Naptha might be another matter, especially if it isn't heated. It would be interesting to know.
PP