Tech Tip – Rupture Disk Assembly

Category: Spray Foam Contractors, Tech Tips   Posted by: demilec

If you see chemical dripping out of the back of your machine, it is quite possible that your rupture disk needs to be replaced.  Rupture disks are designed to burst to relieve pressure in order to prevent dangerous high pressure situations in the hose and other parts of the machine.  These rupture will also wear down and burst over time and need to be replaced, most often on the resin (B) side.




Should you suspect that your rupture disk needs to be replaced, follow these steps:

  •  Put on proper personal protective equipment.
  • Turn main power off and disconnect power supply.
  • Relieve pressure to machine.
  • Wait for heaters and fluid to cool.
  • Remove back heater cover.
  • Evaluate leaking material to determine which rupture disk has failed.
  • Remove existing rupture disk.
  • Clean area.
  • Apply pipe sealant and PTFE tape to rupture disk assembly threads.
  • Install replacement rupture disk, ensuring exhaust hole is at bottom, angled slightly toward outside of heater compartment.
  • Apply 171001 warning label to front heater cover.
  • Reinstall back heater cover

Check for manuals, further instructions, and warnings.


Spray Foam Houston March 30, 2012 at 7:10 am Reply

We’ve been through a few of these and its really not a difficult repair. The Graco folks are quite helpful too if you reach out to them.

Chris April 2, 2012 at 9:55 am Reply

How often to they rupture? I have an E 20 about 5 years old. I take care of it better than the average contractor.

what pressure are they designed to blow at?

Eric June 18, 2012 at 9:31 am Reply

Hello Chris,
There is no specific time frame for how often they rupture, however; some chemicals may allow them to wear down prematurely requiring you to replace them. They are designed to rupture at 5000 psi.

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