Fireproof test enclosure - Page 1
Forum section: electronics / general

author: forrestc
author_rank: Unknown
timestamp: May 03, 2016, 09:47:48 pm
content: A couple times a month I am running some sort of test which needs to be run long-term. Like unattended, overnight.As an example, right now, I'm doing capacity tests on some small (7AH) batteries. A couple of weeks ago I was doing circuit switching validation on a circuit which handles around 5-10A - alternately switching a 300W load on and off using the circuit. And so on.The likelihood that any of these things would cause a fire are relatively low, but definitely non-zero. As I'd prefer to avoid this I'd like to come up with some sort of benchtop enclosure (say 30cm square or so) that I could place these in/on that would contain any combustion and/or meltdown. I'm thinking something like a LIPO charging bag, but more accessible since many of these need both a bit of airflow and some instrumentation.Does anyone know of something like this?Thanks,-forrest

author: Jeroen3
author_rank: Super Contributor
timestamp: May 04, 2016, 05:38:31 am
content: Somethinglike thisperhaps? Available in many sizes.Really solid metal cabinet. There should be something similar available across the pond.Assuming that what you're testing does not contain much fuel. As most plastics today are self extinguishing.If you're burning something for a long time, you might get a scarred desk. But there is a steel baseplate you can insert to lift the DUT above the case floor. Put in a smoke detector perhaps?

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 04, 2016, 12:27:39 pm
content: I'm a bit paranoid about leaving anything on overnight in my timber workshop, particularly anything containing lithium cells. I have an open topped box made from cement fibre sheet (10 mm thick siding for our American cousins) that sits on a chequer plate base with small steel legs to lift it off the workbench. Anything dubious goes in there if I am not in immediate attendance.I have considered linking a smoke detector to a relay to drop out the mains to one wall socket but have not got around to it yet.BT

author: mos6502
author_rank: Frequent Contributor
timestamp: May 04, 2016, 01:27:39 pm
content: A PC case?

author: Fungus
author_rank: Super Contributor
timestamp: May 04, 2016, 01:50:59 pm
content: Plasterboard is often used as "fireproof" for industrial enclosures.It's cheap, it's easy to cut...

author: stmdude
author_rank: Frequent Contributor
timestamp: May 04, 2016, 03:38:03 pm
content: I've done a lot of RC stuff, so..There are LiPo bags that are so big you can fit a small child in them. ( If you're wondering, I wouldn't recommend putting children in LiPo bags. Their mothers get _mad_ )Other things I've seen used are mortars (the kind you crush spices in, not the other one) when it's smaller stuff.Another popular solution are old ammo-boxes.While LiPos do burn hot and with an open flame, it's usually over quite quickly, so as long as whatever the jet of fire hits doesn't support combustion on its own, you should be fine. However, there's another aspect to it as well. They don't burn particularly clean, so there will be black flakes of soot _everywhere_, unless you contain that somehow as well.

author: l0wside
author_rank: Regular Contributor
timestamp: May 05, 2016, 08:31:01 am
content: How about a temperature-proof glass cylinder from the chemistry side (assuming you want to look at what your DuT is doing), placed on a tile.To avoid smoke stains, you might want to add a metal cover with proper holes for the wiring in it.

author: Ian.M
author_rank: Super Contributor
timestamp: May 05, 2016, 09:16:49 am
content: Two 50cm square concrete slabs as base and lid, stacked with ordinary bricks for the sides will contain most burnups/blowups.If its indoors, you then need some sort of negative pressure enclosure round it with the extraction system venting outside via an ignition protected fan - a marine inline bilge blower is probably the cheapest option here - if you don't want your whole workshop contaminated when the smoke gets out.A good enclosure option is to put it inside a small galvanised dustbin with a bungee holding the lid on. Its preferable to locate it outdoors to avoid the need for an extraction system. If you know the likely chemical hazards, you can put suitable absorbent material in the bottom of the bin, e.g sand , cat litter, or for potential acid spills, mix in limestone chips to neutralise it.e.g. if the oxygen and hydrogen in the head space of an over-charged SLA battery explodes, it tends to be rather violent, sprays sulphuric acid gel *EVERYWHERE* and strapping round the side bricks with fibreglass reinforced parcel tape would help keep everything together. All it takes is a cracked or loose busbar resulting in a spark inside the case.Monitoring inside the enclosure is best done with a cheap webcam or CCTV camera that's essentially disposable + some LED lighting.