Had an interesting service call, the client stated that one of the lamps in his shop's F54T5HO high bays "exploded". This is an indoor dog exercise/agility park with 30' ceilings and 4-lamp F54T5HO high bays. Upon arrival I find the staff had already vacuumed up the glass that had rained down. I was skeptical that the lamp had actually "blown up", but rather became loose from not being properly seated in the lampholders and just fell out of the fixture. They were emptying the shopvac when I had arrived and I noticed the glass shards were a grayish color. Once I got up to the fixture on the lift, I discovered the lamp actually appeared to have ruptured from internal causes, one endcap was actually still in its lampholder, and the few inches of glass attached to it also had that burnt grayish phosphor. Other three lamps still working just fine, I relamped, stood there for awhile to see if it may be the ballast that caused it, after 15 mins or so of the new lamp working normally, I left.

Heres my question, I had always thought the internal pressure of fluorescents, even HO lamps was nearly a vacuum. What is the operating internal pressure of T5HO lamps? Could something else have caused this violent rupture? What would make the phosphor coat go that gray color?

Lamps were Satco 6500K F54T5HO's, maybe 5000-ish hours on them.

These fixtures also have good Advance Centium programmed-start ballasts

The lamp was overhearing, maybe due to the oxygen contamination. As a result, the strain in the glass reached a level, where the material gave up and break.
It coukd even start as a small crack there. Causing an air leak in, consequent overheating, so the crack expanding, the leak worsened, till there was enough ogygen to actually burn the inner hot metal parts(filament, its coating,...), the resulting soot causes the grayish coat. And then the crack spread so much, the tube disintegrated there...

Mind you, when fluorescents go, they can be quite loud, even a F15T8 still under vacuum can sound like a small bomb going off! 

Just the other day, I was in the shop doing some cleaning, and threw something into a 30 gallon trash can in there from across the room that was full of a few spent F40's, still under vacuum.  It was so violent that I found glass shards a good 10 feet away from the can, including half of an F40T12.  I thought it was a vacuum too but when they go they go with a bang regardless.

You haven't lived yet until you've had an entire F96T12 fixture, complete with the corresponding 8 foot T12 lamps, fall and lamps "explode" within a few inches of you.  Actual experience.  In a bedroom.  I'm still finding tiny shards of phosphored glass two years later.

When i was at work, after they had removed all the tubes from the fixtures in the library, they let me smash all of them, they were all altos so nothing really to care about, there was two cans, one full of T8 the other full of T12 i took the one full of T12 (about 50 tubes) climbed to the roof with it, and tossed it into the dumpster below, keep in mind i got permission to do this, so no i did not get in trouble, anyway, it made quite a satisfying thundering noise, hehe, the T8's i took my time with, i threw them in one by one, played darts with a few of them


I'm a fool really 

Smashing flourescent bulbs-at a radio station I used to work at-replaced all of the flourescent lamps in the transmitter plant fixtures-they were in one of the trash barrels waiting to be put out for the garbage man.A freind of mine-he releived me on my shift-brought in a large propeller type fan that fit neatly over the top of the trash can-IDEA---We just made our own flourescent bulb shredder-put the barrel and fan outside and fed all of the spent bulbs into that fan-most made a nice HOOOF!!!!when they got chopped up.Then nothing left of those bulbs but fine sand like glass bits and phosphor-months later brought in my SW UV prospectors light and the inside of that trash barrel lit up BRIGHT!!!!

I kindof want to do that now... just to get a barrel full of phosphor

If you want to smash flourescent bulbs with a fan over a barrel-just be sure to do it outside!Big clouds of phosphor dust went up in the air-we stood back after throwing a bulb into the fan.Was FUN,though-both of us taking turns shredding-smashing bulbs in the fan on the trash can.The fan was still OK-a blade slightly bent-fixed it fan was covered with dust-took a while to vacuum it off.Fan then used as an exhaust fan at another transmitter site.

Uhm... releasing mercury and rare-earth compounds (more likely, toxic substances) in the air for fun isn't an great idea 

Revisiting this post, I just remembered another couple incidents of mine involving inadvertently striking F40T12 lamp with a glancing blow (top of steel door jamb while carrying one to another room, for instance).  Not enough to make the lamp shatter and splinter glass and lose vacuum with a violent POP, but think cracked end, phosphor blown clean off that end of the tube by the air rushing in, could hear it for several minutes.

Another time years ago I had a lamp (actually, too bad, it was a nice Vita-Lite Power Twist) randomly lose vacuum (bad seal and/or thermal stress I guess) so violently it blew the phosphor off. I wasn't there at the time to witness it, (light left on and I left the room) but just came back and the center lamp in the 3-lamp fixture was not lit, went to see why and discovered it had lost its vacuum.  The stem hadn't arced (could see right through with no phosphor) so it wasn't a vacuum loss caused by an EOL 'torture'.

Another time, I had a lamp (it was an old GE Mainlighter) get so hot during an intentional EOL frying (the wild orange arcing is fun to watch) that I could smell hot glass after it finally gave up. 

I love frying EOL lamps as well lmao, that metal halide bulb with the broken outer envelope Mentioned in a topic here I tried to destroy in several different ways, first I put it in my 1000w HPS floodlight (the bulb was 175w) and left it. Lit for an hour, came back turned it off, and the arctube was still clean and Un changed, so I turned it back on, and proceded to. Try and thermal shock it with a water gun (the ballast compartment is watertight) it just sizzled and kept going, so the I threw a few rocks at it, it still kept working, started to get frustrated at this point, I took the bulb out of the fixture, and proceeded to toss it all over the rock garden, and stomp on it and all kinds of abuse, then I screwed it back in, IT STILL FREAKING WORKED! Do I left it on for another hour, turned it back off checked the arctube, was still un changed, I turned it back on and started to shake the fixture around while the lamp was operating, lots of pink flashes and flickering, did this for 5 minutes or so, then I shut the thing Off and checked the arctube, it had finally started to bulge, deeming this a victory (and also being bored with it) I took the bulb out and finished it With a brick. Stronk bulb!

Thats what id consider quality lol , be sure to keep that base adaptor at least!

Oh yeah I deffinitly saved the adapter, I only have two of them, wish I had medium to mogul adapters as well but I have yet to find any

The wholesaler i buy things at stocks both (they are used to screw home-user LEDs into HID lanterns and HID-retrofit LEDs into ordinary sockets)

The E27 lamp / E40 socket one is a single Metallic part, like a screw base threaded on the outside and inside with the correct threads. The lamp makes direct connection with the socket's center contact

The E40 lamp / E27 socket one is a cheap Plastic device, there is no way it would stand up to any HID lamp

The ones I have are made of ceramic and stainless steel with a brass center contact.