Snowpulse and Mammut Airbag Incompatibility with ABS Cartridges

The use of ABS airbag cartridges with Mammut and Snowpulse packs is confusing. Snowpulse put out a press release back in November warning that ABS had made changes to their cartridges which would void compatibility with Snowpulse packs, referring to a change in burst disc thickness as the culprit.

Snowpulse and Mammut had previously been marketing the ability to use ABS’s cartridges with their packs, which was attractive since ABS has a lightweight carbon cartridge in Europe. Some people began to wonder if ABS had made the change deliberately to stop this, but why would ABS care if they sold more cartridges? What is the reason for this incompatibility? And more importantly, how serious of an issue is this? After talking with parties on both sides, here’s some back story and what I’ve been able to figure out:

ABS steel cartridges. The copper burst disc has been punctured in the lefthand cartridge. Click to enlarge.

ABS has been developing their airbag system for decades, and in that time has experimented with many different airbag, valve, cartridge, and puncture unit arrangements. At one point their puncture unit (the pointy thing that stabs the copper burst disc in the cartridge to release the air) was a hollow pin design, but they found that once in a while there was a problem with the pin getting plugged up with copper and inhibiting air flow. So they moved to a solid “horseshoe” pin profile, which seemed to mitigate this potential problem.

On April 15, 2010, there was a recall of all European ABS cartridges after an accident where an avalanche victim’s ABS airbag failed to inflate because two burst discs had accidentally been installed sandwiched together in the cartridge, where there should have only been one. To prevent this from happening again, ABS moved all their filling production to be in house and tightened quality control. In addition, just in case the two disc mishap happened again, they reduced the thickness of their burst discs from .3mm to .2mm. If two .3mm discs are stacked together, the puncture unit pin must puncture .6mm of copper, which it cannot do with any guarantee. But if two .2mm discs are stacked, it can easily puncture the .4mm total copper. Thus they had added a margin of safety. All ABS cartridges (steel and carbon) filled after April 15, 2010, the world over should have a single .2mm disc according to ABS.

ABS puncture unit. The cartridge screws in to this and when the trigger handle is pulled, the pin punctures the copper burst disc in the cartridge, releasing the air. Note the design of the pin: solid, with a slot down one side. Click to enlarge.

Snowpulse came out with their own airbag system several years ago using a completely different system which involved pulling a pin to release air (see the Snowpulse 1.0 refill guide to see it). Then, a couple years ago, they developed their 2.0 system, which is very similar to ABS’s in that it uses a pin to puncture a copper disc. The system has passed all TUV tests just as ABS’s system has, including a TUV test that certified it for use with ABS cartridges. But then the TUV informed Mammut/Snowpulse that their systems were failing with ABS’s new .2mm cartridge design, prompting the Snowpulse press release.

Frustratingly, the Snowpulse press release doesn’t explain the problem, and Snowpulse representatives prefer not to comment. If ABS’s cartridge burst disc has only gotten thinner, then the problem can’t be a matter of Snowpulse/Mammut’s puncture unit not being able to penetrate. If you look closer at the Snowpulse/Mammut puncture unit itself, you’ll see that it is shaped differently than ABS’s.

The Snowpulse/Mammut puncture unit. Note that the pin is much larger than the ABS one above and that it is hollow. It is horseshoe shaped, with a slot down the side. Click to enlarge.

One has to wonder if the thinner ABS copper material is getting plugged into the hollow pin. I can’t say with certainty that this is what the problem is, it’s all just conjecture on my part, but it seems a likely candidate. To clarify, this is not a problem when using Snowpulse’s cylinder, which uses a .3mm thick copper burst disc, in a Snowpulse or Mammut backpack.

The Snowpulse press release is confusing because it claims the only incompatible ABS cartridges are from after April 1, 2011 rather than 2010 when ABS had their recall. ABS maintains that no cartridges went out after April 15, 2010 without a .2mm disc, so to be safe, I’d use that date. While I have personally performed at least three tests with recent ABS cartridges in Snowpulse and Mammut packs that have all been fine, there have been a handful of reports from others of their airbag not completely filling, which may or may not be due to some plugged copper restricting the airflow.

A partially inflated 150 liter airbag likely won’t produce the amount of buoyancy needed to keep you on the surface in an avalanche. While there is only a small chance that your puncture pin could become plugged, one should probably err on the side of caution. If you have an older ABS cartridge, keep using it if you wish, just check the weight from time to time to make sure it stays full. I will go through my other posts and update them with this info.

For the time being, Mammut has no plans to fix this incompatibility, so Snowpulse/Mammut users will need to only use Snowpulse/Mammut cylinders. This isn’t really a big deal unless you wanted to use ABS’s carbon cartridge, which is only available in Europe anyway.

Mammut/Snowpulse is working on developing their own carbon cartridge which is still a ways off, and unless they figure out the DOT magic bullet, it will likely only be available in Europe at first. In the US, there are currently no carbon cartridges available from any manufacturer, including ABS, due to lack of approval from the Department of Transportation; who knows when that will change…