Has anyone had any luck with finding or using spherical metal, or acrylic, pressure housings? Made from off-the-shelf hemispheres, or sourced from a supplier of marine mechanics and electronics? For some strange reason, I’ve been having some trouble so much as finding suppliers of such housings; much less ones who offer off-the-shelf enclosures with posted price tags. I’m not sure if it would actually be easier to manufacture my own, perhaps by casting acrylic resin between two hemispheres?
Has anyone here purchased or manufactured spherical housings, before?
I expect the difficulty in finding ready-made spherical pressure housings is likely caused by the difficulties of using them. While you can definitely purchase pairs of domes and attach them together with screws through flat faces at their base,
there are challenges with achieving sufficient water-proofing at the seam (e.g. a single face-seal o-ring may be insufficient for sealing a full enclosure, unlike the end-caps of tubular enclosures which can have overlap with the tube and include multiple seals)
most electronics housings have peripherals (e.g. sensors, thrusters, lights, etc) outside the housing, which require some form of mounting and/or connection to what’s inside the housing, and with no flat faces to interface with those connections are very challenging to make water-tight
there’s limited reason to use spherical enclosures when tubular ones are readily available, easier to manufacture, and easier to use
To better understand where you’re coming from, is there a particular use-case you have in mind where a spherical housing is uniquely superior to a tubular housing? While a sphere itself is a particularly efficient pressure vessel, it’s only useful as an enclosure if you can put something inside it, at which point it can no longer be a sphere. I expect that in general the extra material costs of a thicker tubular enclosure are negated by the benefits that come with using one, particularly in the underwater environment where increased mass can frequently be offset with buoyancy if necessary.
Hi Derek,
As Luis said if you’re interested in Spherical Housings you should talk to Vitrovex. The usual reason for using spherical housings is for extreme pressures which are often not easy to achieve using tubular housings. Vitrovex housings are made of glass and they do a range of different sizes and thicknesses for different depth ratings including down to full ocean depth. We use them for various deep projects including electronics, lighting and also cameras. They sell them as individual hemispheres which are perfectly machined so when you put two together and introduce a vacuum through the fitted vacuum port they will hold a vacuum with no additional seal! Obviously for prolonged use you seal the two halfs using a soft rubber tape with a protective over tape. For optically clear camera use they can make them using BK7 glass. Any two halfs will seal so you can use 1 half of expensive BK7 glass for a camera lens with the back half of cheaper less clear glass. As well as the vacuum port used to seal them they can machine a number of other fittings for electronics control etc. We have a range of housings on a full ocean depth lander project with Subconn connectors and cables interconnecting them. We have pressure tested these in a test chamber to 12,000m water depth…!
Hope that helps…