alpine.adrenaline

I'm setting up three electric fans that I want to be independently therostatically controlled. One to come on at 180 degrees, one at 200, and one at 215. I want to put three probes inline with my heater hose (the hose that has coolant flowing through it regardless of whether the thermostat is open). I need a solid length of pipe, like in the picture, which will house three probes threaded into it, but I'm not sure what material to use. Copper piping I would think would be too thin to thread the probes into but I'm not sure what effect hot ethylene glycol might have on PVC. I'm using the probes and controllers in the other picture.