The defect wasn't at a 90 bend, it's at the end, at the tee. The only valve to slow the wort would be at the pot, and there is one built into the pump. The defect happened where the hot wort was entering and the cold water is exiting.So thinking along the lines of pressure drop here, like @homebeerbrewer was asking about the pump. The pressure of your cooling water looks like it was crushing your beer line. So thinking through that would be:
1. Was the crushed potion at the end where your cooling water comes in? That would be highest pressure on the outside.
2. Looking at your picture, it appears it's right after a right angle bend. Maybe you've got some venturi flow phenomenon going on where you're getting a pressure drop right around that corner.
3. Related to the pump question would be if you have any flow restriction ball valves or anything to slow the beer flow. If so, ideal location would be at outlet of your CFC, not at the inlet. That would keep the pressure higher in the chiller, while still achieving the slower flow rate through.
4. And of course, if that's the part where hot wort meets cold chilling water, you'll have the contraction effect of your wort dropping in temperature so fast. This of course is present in every chiller, but maybe a combination of some of the above left you susceptible at this weakest spot.
5. Maybe some copper welding process put in too much heat to your inner pipe, reducing the copper's mechanical properties.
Water hammer can create pressures in the 1,000-psi range in small equipment and in excess of 10,000 psi in large systems with long runs.
water velocities should be limited to 5 ft/sec unless special considerations are given for controlling water hammer
When a valve is closed suddenly, the momentum of the fluid immediately downstream tends to continue downstream. This creates a high pressure drop that can actually boil the liquid and cause vapor to form in the vacuum. When the vapor re-condenses to liquid, the bubble collapses and the separated liquid columns slam back together, creating a sudden high rise in pressure.
The Bernoulli Principle is based on velocity not pressure. 2 gpm in a 1/2 in. tube is 3.27 fps, which when it hits the 3/8 tube increases velocity to around 5.81 fps. The Blichmann Riptide pump is a capable pump, see the competition chart.
The defect happened where the hot wort was entering and the cold water is exiting.
The water flowing through is straight tap water. No chiller. Pump on the wort side. Water pressure is 90 psi
The collapse only was about 6" or so and didn't affect the solder joints.
Hydrodynamic Design, Part 11: The Water Hammer – WCP Online
Right now, given what's known, I'm sticking with my theory that a water hammer occurred in the outer pipe. Given the op's very high tap water pressure and the conditions present it makes the most sense.
But do that with a thin hose, and reduced velocity due to the restrictions in the tubing, and I'd suggest that that the momentum of the water in there doesn't add up to enough to cause this problem.
I think the crush pressure for 3/6 annealed copper tube is around 800 psi.I think it's the column separation and resulting collapse that caused the damage, not the actual water hammer event, though that increase in pressure would have contributed on collapse. The actual water hammer calculations place the increase in pressure between 100 and 200 psi depending on how fast the valve was closed.
Sorry, 3/8I think the crush pressure for 3/6 annealed copper tube is around 800 psi.
I think the crush pressure for 3/6 annealed copper tube is around 800 psi.
The water flowing through is straight tap water. No chiller. Pump on the wort side. Water pressure is 90 psi
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