EMSS is in an advisory stage currently, so that vendors can see what is needed. Very few devices comply at this stage although we know there are several in production.
Until the industry catches up you could either buy a device that, statistically speaking, is safe - or 'modify your mod'. No boxmod has ever exploded, neither has any single-cell tubemod, as far as we know. Twin cell APVs that comply with EMSS are considered safe.
The problem is thought to be a mix of counterfeit
batteries plus a charger fault plus no fuse, or a similar chain of issues that can occasionally combine to produce an extreme battery failure event. Sometimes that will produce enough gas, and rapidly enough, that the device fragments, if it is sealed or does not have sufficient gas venting capability. The simplest way out of that is to have very generous gas venting capability: big holes. There just isn't any way around that. The trick is to make them look pretty or to somehow fill or cover them so they are not visually unpleasant. This can be done, as we've seen several examples now - one is even sealed to IP65 waterproofing standards.
Twin cell devices are at risk and there is a need to take sensible precautions. Ultimately, you must have good gas venting in a 2-cell tube device as that is statistically where the problems are. Given sufficient gas venting, and some other precautions like a fuse or hot spring, things should be OK.
Single battery devices are statistically safe since one has never exploded. However, there are multiple reports of battery meltdowns even in the most expensive APVs, so it cannot hurt to take some precautions. Perhaps some simple gas venting could be arranged. Note that this needs to be at the top of the tube as much (or more than) the bottom end - this is because batteries are known to swell and block the tube when going thermal in some (but not all) cases. In practical terms this means drilling some holes at the top and bottom ends of the tube, if you wanted to cover all eventualities. It's up to you. Note that the internal burrs caused by drilling
must be removed - 'break all edges' in engineering speak.
Boxmods normally have enough venting due to the squonk holes or easy-open doors.
