Deploying a Modified DevKit Enclosure: Questions on Acrylic vs. Aluminum

Dev Kit Support
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Hi everyone,

We’re part of the Pioneer Program and are getting ready for a deployment of our DevKit with a multiparameter sensor at a depth of ~21 meters. We’ll check in on the setup monthly, and we would ideally deploy long-term. I’ve attached a few photos of our current setup for reference. We’ve drilled a hole in one of the end caps, added a WetLink Penetrator, and properly sealed it with putty epoxy. We’ve also done a successful submersion test in a sink.

We’re currently assessing the standard acrylic enclosure that came with the kit. After reviewing Blue Robotics’ documentation, we have a couple of questions regarding true long-term reliability.

With that in mind, we’d love to hear from the community and the Bristlemouth team:

  1. Acrylic Enclosure: Has anyone deployed the standard DevKit acrylic enclosure for extended periods (1 or 2+ months)? We’re interested in hearing about your experiences with the enclosure’s long-term integrity, especially regarding acrylic creep.

  2. Upgrading to Aluminum: The Blue Robotics documentation recommends aluminum enclosures for long-term deployments. Since our bottom end cap is Bristlemouth-enabled, we can’t easily swap it.

    • Has anyone upgraded the enclosure from acrylic end caps to Blue Robotics 3" aluminum end caps instead?

    • Are there any aluminum end caps available that are bristlemouth-enabled?

  3. PRV for Safety: Upgrading the end cap would also allow us to add a Pressure Relief Valve (PRV). Is a PRV generally recommended on these locked enclosures to ensure safety during retrieval, even from moderate depths?

If upgrading to an aluminum enclosure is the recommended step, we would still try to deploy our current setup for a month. Any feedback on our current setup would be appreciated.

We’re really excited to get this deployed and want to do it right. Any advice, shared experiences, or official recommendations would be hugely appreciated!

Thanks,
Caesar

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Hi Caesar, It doesn’t seem like a PRV would be necessary. You will be enclosing it at 1 atm, and there isn’t an external air source at depth. For long-term deployments with these kits we have been considering a vacuum system to pull -12 psi to test the seals.

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Hi @VincentSmith, Sorry for the delay, and thanks for the input!

The suggestion to vacuum test the seals is a great point, and definitely a best practice we’ll look into.

My thinking on the PRV was about a what-if scenario: if a slow leak develops at depth, could the enclosure equalize to the external pressure and then be dangerously pressurized when we bring it back to the surface? That’s the main reason I was leaning towards needing one. What are your thoughts on that risk?

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Hi @Caesarh I really don’t think this is a risk, but if you are worried about a potential leak or having dead air space that could change in pressure, Eric Stackpole has an interesting idea using materials like silly putty. Perhaps it could be used to protect the electronics within a sealed case too as an inexpensive and non-permanent backup: Can shear thickening materials like Silly Putty offer a better way to waterproof electronics? | Experiment

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Thank you for the feedback @VincentSmith! That’s an interesting idea!