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ethylene glycol

ethylene glycol

ethylene glycol

(OP)
I'm new at plastic extruding and am looking for the expansion rate of a 70/30 ethylene glycol water mix for an expansion tank. I've worked out the pressures and flow but cannot find the proper volume for a reservoir tank for expansion from ambient to approximately 320 degrees f.     

RE: ethylene glycol

Wow.  How much pressure do you need to keep it from boiling at 320F?

 

Mike Halloran
Pembroke Pines, FL, USA

RE: ethylene glycol

(OP)
I've been there, actually the nominal temp is about 275 F for some specialized compounds, I'm erring on the upper limits. I know water expands at about 3% and a 50/50 mix expands at about 4% but I don't know if the expansion rate is linear. I also know for every 1 psi increase in pressure you gain about 3 degrees in the boiling point in a closed system. Auto systems run at about 13 to 15 psi to raise the boiling point to about 275 degrees, but I don't know the total volume in the system. I'm also worried about heat transfer and flow rates, ethylene glycol at a 50/50 mix loses about 20% heat transfer capacity and I'm at a 70/30 mix.
 

RE: ethylene glycol

(OP)
Mike,
a calculated pressure for 320 degrees at 70/30 mix at ideal conditions would be 28 psi. They are running the pumps at about 50 psi, hence a blown flexible hose is almost lethal to anyone in proximity. I designed a circuit to shut down the pump on any pressure loss, but at 50 psi the burst is still substantial before shutdown. I hate adding more things because the more you add the more can go wrong. My background is maintenance and I try and and make it simple to troubleshoot.  

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