Anyone ever heard of a PVC air loop system catastrophically failing?

[Eric R]

I've moved mostly over to the dark side (marine/reef tanks) over the last couple years. I still have two planted FW tanks setup, and some pond plants.

My clownfish have been laying eggs, and I've purchased equipment to grow out phytoplankton and rotifers, and setup a couple breeding tubs to raise the clownfish larvae. I bought the linear piston air pump the co-op sells, as I got tired of the nano USB pumps failing after a year or less of use., and this way I have a long-term, quiet, reliable air supply.

I'm on a reef keeping discord, and one of the members is a very experienced aquarist at a large public aquarium (he has some specific experience with designing equipment to transport fish collected at depth under pressure). He has expressed concern about what happens to PVC if it fails with a pressurized air system, and has suggested using ABS designed for pressurized air instead (he's also said that with the low pressure the linear piston pumps run at, it's not likely to ever be an issue). I think he's mostly thinking of commercial scale air installations.

After researching alternatives, it really seems to me like PVC is the easiest and most affordable option, and I think any failure that would result in PVC creating shrapnel seems incredibly unlikely with how we setup systems.

That being said, has anyone ever heard of a PVC air loop system catastrophically failing in some manner where the PVC did crack or create shrapnel? I am setting this up in a high school classroom, so I want to make doubly sure that it's quite safe.

Edited October 1, 2023 by Eric R
Typo, I wrote ABS, and meant PVC

[lefty o]

with the low pressure, and volume of air being used in an aquarium or modest amount of aquariums, i think its a non issue. sort of related, back when i was a printer we had shop air plumbed to the presses by large pvc pipes, when those failed, there was no shrapnel, but holy heck your ears would suffer if you were within a hundred feet of the break.

[Tanked]

The only pvc failure that I have expierenced arose from using the wrong solvent and the installer mixing pvc and cpvc components.  The joints failed.

Your pump won't produce enough pressure to cause the pipes to burst.  Big box pvc pipe and solvent should be more than adequate.

https://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html

[Galabar]

https://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html

It looks like 3/4" schedule 40 is rated at about 400 psi with a burst pressure of 1500 psi.

I think the air pump that we use (including linear) create less than 5 psi.

https://www.thepondreport.com/linear-air-compressors-air-pumps.shtml

Edited September 30, 2023 by Galabar

[Eric R]

Thanks for the replies.

I realize I accidentally wrote "After researching alternatives, it really seems to me like ABS is the easiest and most affordable option" when I meant to write "After researching alternatives, it really seems to me like PVC is the easiest and most affordable option"

I feel pretty comfortable using PVC, I just wanted to ask a group of experienced aquarists to see if anyone had ever even heard of a problem happening using PVC for an air loop. Unlikely things that have even a remote chance of happening will usually happen at least once or twice if they are done often enough.

On 9/30/2023 at 9:38 AM, lefty o said:

with the low pressure, and volume of air being used in an aquarium or modest amount of aquariums, i think its a non issue. sort of related, back when i was a printer we had shop air plumbed to the presses by large pvc pipes, when those failed, there was no shrapnel, but holy heck your ears would suffer if you were within a hundred feet of the break.

Out of curiosity, do you know what kinds of pressures you were running? And would the wall of a pipe usually fail, or would it be a connection at a joint?

[gardenman]

The linear piston air pump would fail before you could achieve a high enough pressure to rupture PVC. Now, having said that, PVC pipe isn't rated or designed for compressed air/gases. It's rated for water and other fluids. Insurance issues could arise should something go wrong if you're using it in a non-approved manner. Not as much of an issue for a homeowner with a small fish room but for a school....

The odds of anything going wrong in an aquarium air system are absurdly low, but there are still some risks. PVC gets brittle when too cold and can shatter at lower than rated pressures if overly cold. It can also soften when too warm, so placement needs to be considered. If you're keeping the loop in "normal" room temperature, and away from a heat source, you should be quite safe. Here in NJ, you would likely need to use a licensed state-certified school contractor to install the system. At great cost. They don't let just anyone do anything in a classroom. There would need to be a contractor hired, experts consulted, designs submitted, school board approval, etc. before you could do it.

[lefty o]

On 10/1/2023 at 3:07 AM, Eric R said:

Thanks for the replies.

I realize I accidentally wrote "After researching alternatives, it really seems to me like ABS is the easiest and most affordable option" when I meant to write "After researching alternatives, it really seems to me like PVC is the easiest and most affordable option"

I feel pretty comfortable using PVC, I just wanted to ask a group of experienced aquarists to see if anyone had ever even heard of a problem happening using PVC for an air loop. Unlikely things that have even a remote chance of happening will usually happen at least once or twice if they are done often enough.

Out of curiosity, do you know what kinds of pressures you were running? And would the wall of a pipe usually fail, or would it be a connection at a joint?

it was something like 150psi, and it would just blow out wherever it felt like. this was some special green colored pvc that was made for air. our maintenance guy hated that stuff. we were never too happy with it when it failed either, as bad things happen on a press when you lose air while running.

[nabokovfan87]

On 9/30/2023 at 5:50 AM, Eric R said:

That being said, has anyone ever heard of a PVC air loop system catastrophically failing in some manner where the PVC did crack or create shrapnel? I am setting this up in a high school classroom, so I want to make doubly sure that it's quite safe.

Your best bet is to make sure you glue it and to use something like this:
 

This will ensure it's a low pressure system and as safe as possible.

On 10/1/2023 at 5:13 AM, gardenman said:

PVC gets brittle when too cold and can shatter at lower than rated pressures if overly cold. It can also soften when too warm, so placement needs to be considered.

Very good point.  It may have a "shelf life" so to speak, but generally I think a lot of people set it and forget it.

[Galabar]

Again, from the info above, it looks like the linear piston air pumps are going to create < 5 psi, or about 80x less than the operational pressure of PVC and 300x less than the burst pressure.

https://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html

https://www.thepondreport.com/linear-air-compressors-air-pumps.shtml

 

[Tanked]

On 10/1/2023 at 5:24 PM, Pepere said:

30 something years ago I made a potato canon using pvc and hair spray as the accelerant with a flint striker inside through the cap to ignite the charge.

We learned if you used a bit of pvc tube to cut the potatos and then freeze the plugs it expanded slightly with the freezing to make a tighter seal for less blowby gasses and the thawing potato lubricated the tube.  We joked that frozen Potatos would break the sound barrier…

 

The PVC never failed from that abuse…

And I dont recommend people do the foolish things I did back then.

I've resisted the urge to build one, but I have seen them in action. The fun began when the group of guys I was watching switched to apples.  When it began to rain applesaue, the noise didn't stop the deer from comng out of the woods at the far end of the field .

[Eric R]

On 10/1/2023 at 8:13 AM, gardenman said:

The linear piston air pump would fail before you could achieve a high enough pressure to rupture PVC. Now, having said that, PVC pipe isn't rated or designed for compressed air/gases. It's rated for water and other fluids. Insurance issues could arise should something go wrong if you're using it in a non-approved manner. Not as much of an issue for a homeowner with a small fish room but for a school....

The odds of anything going wrong in an aquarium air system are absurdly low, but there are still some risks. PVC gets brittle when too cold and can shatter at lower than rated pressures if overly cold. It can also soften when too warm, so placement needs to be considered. If you're keeping the loop in "normal" room temperature, and away from a heat source, you should be quite safe. Here in NJ, you would likely need to use a licensed state-certified school contractor to install the system. At great cost. They don't let just anyone do anything in a classroom. There would need to be a contractor hired, experts consulted, designs submitted, school board approval, etc. before you could do it.

The manual says the pump is rated to run at 110 - 180 mbar, equivalent to 1.6-2.6 psi. Pretty sure we're more than fine, especially since noone has chimed in with having had a failure issue of this nature with this kind of pump.

Remind me to never teach in NJ. I don't think I'll have any issues here.