Film-Tech Forum ARCHIVE: Running with the lamphouse open

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Posted by Christopher Meredith (Member # 3767) on 05-21-2007, 10:34 AM:

When I came into work Saturday evening, I was told that projector #8 (our big house, 4kW) was "too hot." Upon inspection, it was immediately clear that the roof exhaust fan was not running. The console was way too hot to touch and the heat was ripping off the entire unit. It was running Shrek and had about 20 minutes left so I let it finish.

Since then, I've been running it with the back panel removed and the side panel open, with an industrial fan blowing into the side and another sucking air out the back. We had to rig up som shades to prevent the excess light from spilling into auditoriums, but this has kep the unit sufficiently cool until a new fan can arrive tomorrow morning.

Unfortunately, other projectionists here are scared to death by this arrangement and have made their complaints known. They are trained enough to run the booth properly but know next to nothing about how the machines actually work. (The second-most trained guy, next to me, when he saw the projector was running hot was convinced the projector belt needed changing!)

Anyway, I was wondering about everyone's experiences having top run in thsi compromised fashion. Personally, I am not a bit concerned by this setup. I find it far safer than the alternative, and far preferable to being down our big house on the opening weekend of Shrek 3. Any thought?

Posted by Jack Ondracek (Member # 1466) on 05-21-2007, 11:00 AM:

There are a lot of people here, who can pick this apart better than I, but...

I'm leaning toward your other projectionists' attitude about this. An "industrial fan" might pull the heat that's radiated to the sides, but may not do much for the bulb seals. If that bulb blows... for ANY reason, related to the failure of the fan or not, you're likely to have glass flying everywhere. If any of that so much as touches one of your staff, things could get really exciting around there... especially for the lawyers. Having that door open is a risky service issue, even with a cold bulb. Intentionally leaving it open, then running the thing AND allowing people in the room with it... well, I hope the company insurance is paid up!

Another issue here, is whether you were authorized to put your company at-risk like this. Modifying a lamp like that is a decision I would never allow an employee to make on his own... especially since I carry all the liability and he carries none. Your intentions may have been honorable (keeping the screen up), but you probably should have had something like that authorized... in writing, by someone very close to the top.

I saved a show like that... once... for the same reasons, with about the same time left on the show. At the end of the performance, that screen was officially down until I'd replaced the blower.... AND the bulb. I wasn't ready to risk that it hadn't been overly stressed by the experience. However, in that case, it was my theatre, my lamphouse, my bulb, my choice... and I cleared everyone out of there but me.

Posted by Gordon McLeod (Member # 33) on 05-21-2007, 11:25 AM:

With a cover removed the odds are electrical parts are exposed which is leaving you liable should someone get hurt
also air must go out the stack opening in many cases to ensure the correct directional flow of air inside the lamphouse
I also wonder why the lamphouse didn't shut down with the blower dead as the sail switch should have done that also to run with the covers off usually means defeating safety switchs

Posted by Randy Stankey (Member # 64) on 05-21-2007, 11:28 AM:

I'm with Jack.

To save a show, OK with reservations. But, until you can get that blower back in operation, the house is down!

The metal side and back panels are for more than just keeping the light in. The help direct the cooling to the lamp and they also protect you from schrapnel damage if the lamp should ever explode.

Trust me: You DO NOT want to be within 20 feet of a xenon lamp if it explodes! Yeah! I said 20 FEET!

Stop jerking around and get that blower repaired! [Wink]

Posted by Christopher Meredith (Member # 3767) on 05-21-2007, 11:31 AM:

Perhaps I should clarify. The blowers that directly cool the bulb are functional. It is only the console exhaust that is down. The bulb is being directly cooled as normal.

Gordon, yes, I did have to defeat 2 safety switches to run with the doors open. Also, these units do not have a sail swicth for the roof stack. It appears they used to, but no longer do. The units at my previous theater did not have them either. (Actually, at that theater, 8 of the 2kw units didn't even have roof exhaust at all!)

I am aware of the liability issues involved. But if the bulb doesn't explode and no one touches the electrical components, that becomes a moot point, no? I guess my question is from a technical perspective. Should I be concerned about an equipment failure due to running this way?

Posted by Randy Stankey (Member # 64) on 05-21-2007, 11:53 AM:

No. You're missing the point.
The lamphouse doors keep the air flow INSIDE and make sure it blows on the LAMP, not all out into the room. Even with the blower blowing on the lamp, it might not get enough air to cool it the way it's supposed to be.

Yes, you SHOULD be concerned about the increased chance of failure.

quote: Christopher Meredith
But if the bulb doesn't explode and no one touches the electrical components, that becomes a moot point, no?

But, if the bulb DOES explode YOU will become moot!
Have you ever heard the words "Joint and Severable Liability?"

You defeated TWO safety mechanisms, designed to protect people from just the sort of danger you are worried about? That kind of thing will earn you a Darwin Award!

It's YOUR neck that's on the chopping block, RIGHT NOW!
Basically, you're just lying there hoping the axe doesn't fall!
Why don't you paint a dotted line around your neck while you're at it?!

Just quit dicking around and get somebody to go up there and check it! It's probably just a worn out belt. A can of spray-on belt dressing might get you back up and running until you call the repair man.

For the amount of effort that is required to go up on the roof to check the blower, you're putting yourself and a lot of other people in all kinds of danger!

Posted by Dominic Espinosa (Member # 2122) on 05-21-2007, 11:53 AM:

If the "bulb coolers" were functioning the unit wouldn't be that hot.
That roof stack is essential in cooling it. I'd put those industrial fans on your roof in place of the appropriate blower so as to create the correct airflow.
A 4k house like that should have every safe-guard known to man on it for safety's sake, replace your sail switches.
Incidentally you are at immense risk of that bulb failing in a catastrophic manner that will include physical damage to your lamp house.

We all understand you want to keep your shows running, it's commendable however the safety of your projection staff takes precedence.

Best of luck.

Posted by John Walsh (Member # 168) on 05-21-2007, 12:14 PM:

I understand your position, but I would still agree with people who would not continue running in this way. Although I don't know the make of the console, most of them require the side panels on to keep the air flowing in the right places. Just because one blower is running doesn't mean everything is OK. You are forcing a risky decsion on other people if it explodes, in addition to maybe overheating a $1200 or so reflector.

The fact that you did not know the sail switches had been removed shows you either are new at projecting or have not inspected your projection room as should be done. If you are new, then please heed the advise given here and don't get defensive. If you are not new to projection, than note that the reason I am a little harsh is that this is the kind of poor operation that has the industry in the poor state it's in.

Use this as a learning lesson, and find a portable blower that can easily fit on the stack to get through emergencies

Posted by Jack Ondracek (Member # 1466) on 05-21-2007, 12:23 PM:

quote: Christopher Meredith
I guess my question is from a technical perspective. Should I be concerned about an equipment failure due to running this way?

I think the point here is that the technical side of this problem is a lesser issue. Yes, you might get away with it. However, there are lots of things you CAN do, even though you SHOULDN'T. Therefore, this becomes a judgment issue that bears on how maturely you approach your job.

Yes, you kept your show on the screen. However, to do that, you bypassed safety components and intentionally operated potentially dangerous equipment in a manner that could unpredictably cause damage and injury. I seriously doubt that any booth manager is allowed a call like that, and that is the main point of my argument. You would have been far better off to have explained how you approached the big picture, thinking of your employer at least as much as being able to show off your technical prowess. That you haven't done so would put serious doubts in my mind as a potential employer. Without serious training and agreements as to the parameters of your job, I'm not sure I'd be comfortable with you in the booth. That might be a shame, since you showed the initiative to even approach the problem in the first place.

Incidentally, the stack blower that John mentioned is a great idea. Several multi's in our area have done exactly this, as their way of dealing with the problem you have now. Once you get through this situation, get one of these things (probably from Grainger), then see if you can arrange your booth so the blower can be placed on any lamphouse that might need it.

Posted by Louis Bornwasser (Member # 3063) on 05-21-2007, 12:55 PM:

Insurance: you don't have any if covers and switches are modified.

I agree that unless you are the owner or his rep: the house stays down unless authorized in writing. Even then NO ONE except you should be allowed in the same room with the equipment.

From a technical standpoint, the bulb is dumb and if its blower is blowing AND THE HOT AIR CAN ESCAPE, the bulb is happy. I would 1. reduce the current to a lower level even if the screen is darker.(4000 watt belb to 80 amps or so.) 2. Remove the exhaust hose from the top of the lamphouse, which at least allows the hottest air to escape. 3. leave the rest of the covers on. If you have an emergency blower, then use it. (Ours is made out of an old tube from shipping in a screen and a very large muffin fan.) Louis

Posted by Chris Dugan (Member # 3893) on 05-21-2007, 01:00 PM:

quote: Louis Bornwasser
Remove the exhaust hose from the top of the lamphouse, which at least allows the hottest air to escape. 3. leave the rest of the covers on. If you have an emergency blower, then use it. (Ours is made out of an old tube from shipping in a screen and a very large muffin fan.)

We do the exact same thing when the fan on the roof dies. It gets hot in booth, but I know for sure that if the bulb does decide to go, that glass isn't going to go every which direction and my operators are safe.

Posted by Chad M Calpito (Member # 3736) on 05-21-2007, 01:07 PM:

While your intentions were good, it wasn't a good idea to run a projector with the lamphouse open. I have to agree with the posts in this topic. Plus, it is mainly a safety issue. In my booth, Safety is a huge issue and I would never allow something like this to happen.

Posted by Monte L Fullmer (Member # 2797) on 05-21-2007, 01:36 PM:

Yes, get the equipment fix as soon as possible.

Like one theatre I know of that had a old Christie CH-20 console that had all of the safeties defeated since you had to open the door to do the focus and azmuith alignments while the bulb was running [Eek!]

,, and the owners didn't pay any heed to safety or even cared how this procedure was handled...nor even worried on getting the adjustment points fixed so that the usage of the allen wrench was used...

...it was totally insane how this was all done....

I have X-90 consoles in my area and I've made a emergency stack fan from a muffin fan that is mounted in the back door, take the duct from the ceiling and attach this muffin fan with a long cord to have the unit run continuously if I lose a roof fan. Doing this, does keep the console on the cool side, but I do agree - does warm up that section of the booth a bit.

What is the pits though is when that cathode fan in the console decides to cease functioning...no light then....why one has to take that unit off and do the oiling procedures required for those small Dayton motors...twice a year..

-Monte

Posted by Scott D. Neff (Member # 185) on 05-21-2007, 03:14 PM:

Not that I ever enjoyed it, but we ran two old Xetron consoles without the back and non-op side covers for YEARS without any problems. It never looked pretty, but it kept the place running since the landlord refused to replace any of the roof exhausts.

Posted by Christopher Meredith (Member # 3767) on 05-21-2007, 03:15 PM:

I don't know how I gave the impression that I wasn't planning on getting this fixed. I thought I had indicated in the OP that the new fan would not arrive until tomorrow morning. We had an HVAC tech out here until almost midnight Saturday night working on the unit, his conclusion being that it was in need to replacement and that the motor is OEM and needs to be ordered from the mfg. It will be fixed at the earliest opportunity.

Second, this was not a call I made on my own, though the person who has the authority to make this call had the same idea as me.

Third, I agree that the lack fo sail switches is a bad thing. But when you inherit a setup that has changed hands and companies numerous times, it's difficult to determine which odd things were done intentioanlly and for a good reason and which ones were the result of negligence somewhere along the line. I admit to at least partially dropping the ball on this point.

As far as the issue of proper airflow, this is the one that most interests me. It has been stated ibn this thread that the design and placement of the lamphouses and the exhaust hardware is done intentionally to create a specific airflow for the general cooling of the interior of the lamphouse. Is that affected by Monte's suggestion of rigging up an emergency fan that pulls air out the back of the X-90, rather than out the top as it is designed to do?

In other words, if Monte's suggestion works, I don't understand why my temporary solution wouldn't.

For what it's worth, I found out after the original post that the parts will not actually arrive until Wednesday morning. Given that fact, and given that it is not a non-peak business time, we've decided to run without that house at all. Again, I hope I enver gave the impression that this was intended as anything other than a short-term, temporary "band-aid" until the repair could be completed.

Posted by Chris Slycord (Member # 4239) on 05-21-2007, 03:50 PM:

There are a couple major distinctions between your's and his.

In your's the side and back are wide open, ready to let glass fly everywhere.

In his, he doesn't do anything with the side like your's and the back is not open either. He mounted a fan to the back panel. So the only part that's kind of open is the small vent for the fan.

So his idea is far safer. Safer in the sense that people/equipment within 20 feet won't have shrapnel thrown into them in the case of the bulb breaking.

Posted by Alex Grueneberg (Member # 2652) on 05-21-2007, 03:56 PM:

I had to do this once with a 4.5k. Honestly, although your concern is justified I'd leave the panels closed. Make your case known that the projector is very hot to the chain or management but if they want to continue to run the unit its there game. On Christie's some of the other operators here would take off the back panel (auto focus adjustments) and plop a fan right there however that still runs the risks of glass shooting out if the bulb decided its had enough.

Small note: We picked up a small yet powerful blower fan from Grainger that fits perfectly on the top vent snood of our SLC's for exactly this issue. True it does just blow the exhaust into the booth but it keeps the unit cool, and a handy thing to have around.

Good luck.

Posted by Christopher Meredith (Member # 3767) on 05-21-2007, 04:17 PM:

Chris, I was referring entirely to the technical aspect. I realize that having the doors open presents a risk if a bulb explodes. But if the bulb is operating at proper temperature and the hot air is sufficiently removed from the environment in such a way that there is no greater risk of the bulb spontaneously exploding in my rigged setup than there is in normal operation, then I hardly have to worry about what happens if the bulb explodes. Why would it? It only has ~250 hours on it and is being run at proper current levels.

Besides, the operator only needs to be anywhere near the machine long enough to push the START button. Any adjustments to the presentation can be made from the non-op side. That particular machine is at the end of the booth and faces a wall.

Again, please don't misunderstand me. I do not think safety is pointless. But from where I'm coming from, in my opinion, it doesn't present a significant risk. I am merely disappointed that the other operators don't see it that way. It was determined that this is not a decision that should be made for them, however, and we've decided to go ahead and not run the machine at all.

For my own education, I would be interested in learning more about the assertion made earlier that the panels and position of the stack exhaust are essential to proper airflow and cooling. In other words, I would like to learn how my setup is inferior (aside from the safety concerns) to the normal operation of the projector and exhaust system.

Posted by Louis Bornwasser (Member # 3063) on 05-21-2007, 04:50 PM:

The air around the bulb is taken care of by the blower attached to the bulb mount. As long as air can get out the top of the box, the bulb should be more or less OK. Reducing the current and allowing the very hottest air out (by any method) should allow reliable operation.

Our safety concerns stem from the fact that you (probably) don't have the authority to put anyone (including yourself) in harm's way. It is almost certainly not your option from a corporate viewpoint. I would most certainly not let any employee of mine, regardless of qualification do some things that I would do myself.

Also, I never thought this situation was to be permanent! Louis

Posted by Christopher Meredith (Member # 3767) on 05-21-2007, 05:15 PM:

And that is why this was not a unilateral decision. I would not have done it if I 1) did not think the risk was minimal and 2) did not have permission to do so.

I was just wondering what others' experiences were in this area. I am appreciating the feedback with suggestions of other ways to work around this type of problem. After the issue is fully resolved, we will most definitely look into constructing a suitable backup option.

Posted by Scott Norwood (Member # 30) on 05-21-2007, 05:23 PM:

I've been told by a few technicians that lamps up to 2kw can be safely operated without roof exhaust on a temporary basis. I've had to do this a few times and haven't seen any real issues with doing so.

I've seen lots of booths without sail switches/exhaust failsafes (units either missing entirely or bypassed). Is this really that uncommon? It doesn't seem like a real problem as long as the operator is attentive enough to check to make sure that the roof exhaust blower actually is turned on and working.

Oh, and I would never run a xenon lamp with the covers removed. I've seen what a 2kw bulb will do to a fully enclosed lamphouse when it blows up while in operation. I'd hate to see what a 4kw bulb would do, especially with a fan waiting to propel the bits into the booth.

Posted by Richard May (Member # 2627) on 05-21-2007, 06:26 PM:

Scott, temporary????? A lot of independents I service don't have any exhaust at all. It doesn't seem to matter what I tell them. They don't want to have it installed. Makes it nice and toasty on those cold winter nights..... [Wink]

Posted by Frank Dubrois (Member # 3042) on 05-21-2007, 06:26 PM:

If I worked there, I would simply refuse to run the projector. The potential danger of the lamp exploding is to severe to be anywhere near that projector when it is running. The company would lose $$ until they got someone in there to fix that unit because I would simply refuse to put myself, or anyone else, at risk to simply run the projector as is. If Shrek is in that house, switch it with another print that doesn't play, but either way, that projector simply would not run...I don't think they could even fire you for refusing to run it either. It's simply a stupid gamble.

Posted by Richard May (Member # 2627) on 05-21-2007, 06:28 PM:

Easier said than done Frank. They will just get someone else to run it if they had to. A lot of these employers don't care. It's all about the money.

Posted by Mike Blakesley (Member # 26) on 05-21-2007, 06:35 PM:

quote: Scott Norwood
I've been told by a few technicians that lamps up to 2kw can be safely operated without roof exhaust on a temporary basis.

Our Christie 2kw lamp actually ran that way for several years. When it was installed, we had a small fan above the booth ceiling but no roof fan that I knew of. The "technician" (who's now dead) apparently thought the roof fan was not necessary and that the cooling from the lamphouse fan and the attic fan was good enough. We never had bulb problems amazingly.

John Eikhof was the first person to question the lack of a roof fan and he actually climbed up there and determined that we DID have a roof fan but it just wasn't hooked up! So we ran a wire to the booth, plugged that fan in and now we're coolin' baby.

Posted by Richard May (Member # 2627) on 05-21-2007, 06:42 PM:

That reminds me......An Indian theater close to where I live that I serviced ran 2 super 80 lamphouses I think. They were definitely 4000 watt bulbs though. Neither one had a booth exhaust. They were in the original booth. They were run all summer long with no problems. Obviously I'm not saying that this is good to do. I just don't think you're in immediate danger by doing this. BTW, these were run with all the covers in place.

Posted by John T. Hendrickson, Jr (Member # 849) on 05-21-2007, 06:50 PM:

Correct me if I'm wrong, but don't most lamphouse manufacturers have specs for CFM that the exhaust system should pull for proper cooling purposes? That being said, why play games? If the bulb blows, wouldn't that void the bulb warranty? Then of course you have reflector damage and other possible damage as well.

When my roof exhaust goes, end of show until the H_Vac guy comes in to do the necesary repairs.

Just my two cents. [Smile]

Posted by Richard May (Member # 2627) on 05-21-2007, 07:03 PM:

John you're right. A lot of theaters don't see it that way though. They think it costs too much to put in a proper exhaust. They don't understand that in the long run they will save money on bulbs and other booth equipment that will fail sooner than they should. Like I said though, I have seen very few, if any, lamps explode because of no exhaust. I have seen them fail early but not explode. Again, this is only with the independents that I service and I'm not saying that it's with every one of them...just the majority of them.

Posted by Gordon McLeod (Member # 33) on 05-21-2007, 07:04 PM:

What I have in all locations is a squirel cage blower mounted in a metal box that can sit on top of the lamphouse powered by a line cord that will create sufficient suction to vent the stack into the room with out any covers removed

Posted by Frank Dubrois (Member # 3042) on 05-21-2007, 11:33 PM:

quote: Frank Dubrois
It's simply a stupid gamble.

Yeah, like I said..........

Posted by Monte L Fullmer (Member # 2797) on 05-21-2007, 11:46 PM:

quote: Richard May
It's all about the money.

(seems like a lot of small time, two bit wannabe big shot theatre owners rather play the number$$$ game than actually doing the business right..)

Like one single screen cinema I know of that kept all of their spare bulbs like a pak rat-12 yr plus of used bulbs, and what really got me was that there were a few CXL-30 bulbs in this spare bunch of bulbs with makeshift cathode connections attached..and this cinema has a Super80 lamphouse which uses the CXL-30R bulb [Eek!]

talk about cheap and stupid in someone digging up used HTP bulbs to burn in this STRONG lamphouse...( I don't know how they managed to burn these wrong bulbs in that lamphouse, but was told that it was somehow done by their so-called technician -which I really don't want to know how it was connected..)

I grabbed all of these spares and got them out of their misery so no-one whould have a blink of a chance doing any makeshift installs again.

Posted by Chris Slycord (Member # 4239) on 05-22-2007, 03:09 AM:

quote: Christopher Meredith
Again, please don't misunderstand me. I do not think safety is pointless. But from where I'm coming from, in my opinion, it doesn't present a significant risk. I am merely disappointed that the other operators don't see it that way. It was determined that this is not a decision that should be made for them, however, and we've decided to go ahead and not run the machine at all.

The problem is with the definition of "significant risk." You say the risk is insignificant because it's unlikely that the bulb will blow. But if something bad did happen, there would be SIGNIFICANT damage (both to people and the equipment nearby).

But as was mentioned, just detaching the blower stack from the unit will probably let quite a bit of the hot air out. Anyone knows that hot air rises. So some of it will tend to shoot up simply from convection. Plus, inside the lamphouse the air pressure will be much higher than outside which will cause the air to tend to go out any opening.

You should definitely try that before doing anything more involved, especially if your lamphouse sucks in cool air from a lower section than where the hot air will be let out.

Like if you had some way of measuring the temp of a bulb, light a similarly lamp (same model lamphouse and same wattage) and see what it runs at. Then test the temp of the lamp that's got the stack pulled off. If it stays in a similar temp, you'll be ok. And it'll be safe/cheap.

Posted by Rick Raskin (Member # 1561) on 05-22-2007, 05:08 AM:

quote: Christopher Meredith
we've decided to go ahead and not run the machine at all.

Good choice. Running carbon arcs, I once refused to run a show because of a failed exhaust. Management didn't like it but the exhaust was fixed the next morning.

I for one would NEVER compromise safety.

If nothing bad were to happen you'd get an "atta boy". But it only takes one "aw sh*t" to wipe out 1000 "atta boys".

Posted by Anslem Rayburn (Member # 1267) on 05-22-2007, 05:31 AM:

I've run 2K bulbs for 2 days without exhaust fans. We don't open the lamphouse, so our only risk is shock (as in "Holy shit, what was that?!?!?") and lamphouse damage. We've only done it when the local shop is closed (aka the weekend), and it's only happened twice. I would NEVER run a machine that might harm anyone. Disgruntled customers are better than scarred or dead staff. We try to keep spare motors and belts on hand, but stuff happens. I have no problem risking the lives of bulbs and lamphouses for the sake of good PR. Human life is a different beast.

Posted by Michael Moore (Member # 3867) on 05-22-2007, 09:08 AM:

You know on this topic; something i have worried about is' my projector has its blower mounted on the top of the lamp house. We have never vented it to the outside because we really have no way to do it at this time. So the blower exhausts right in the room. What I'm afraid of is the bulb exploding and the fan pushing all the glass from the reflector and bulb into the booth. Should I be concerned with this?

Posted by Jack Ondracek (Member # 1466) on 05-22-2007, 09:22 AM:

I suppose a little bit could find its way up the stack... certainly not all of it. It's doubtful that a stack blower would pull enough to yank any glass that hadn't been directly shot at it.

Still, you could probably get some hardware cloth (wire mesh) and attach it to the blower. Don't get it too fine though... you don't want to decrease the blower cfm.

Posted by Randy Stankey (Member # 64) on 05-22-2007, 11:01 AM:

If the lamp explodes, it could cost you a couple-three thousand dollars to repair the damage, whether the covers are on or whether the blowers are all working or not.

If a lamp explodes and the schrapnel hits a person, he or she will, AT MINIMUM, need to go the emergency room for stitches. If glass hits them in the face or if a large chunk of the lamp hits them in a vital area, they will end up being admitted to the hospital if not maimed or killed.

Now, let's assume that the lamp has the same chances of exploding whether the covers are all closed or not. Even if it's only a 0.001% chance, why would you want to risk hurting somebody?

It's just really simple to keep the covers on and cover your ass in the mean time.

What about the "numbers game"? How does management think it's saving money? If the lamp explodes, it will COST them LOTS more money than taking this chance saves them.

If that lamp goes, the projector will be out of commission until it is repaired. You will lose no less than one or two shows. Refunding a house full of customers on a Saturday night is going to cost you plenty! If the explosion puts you out of commission for a day or more, you will lost THOUSANDS and THOUSANDS of dollars! FAR more than the few bucks you saved by not paying for the repairs you need in the first place.

I understand the drive to keep the projector on-screen. It's a matter of pride and concern for your craft. "The show must go on!"

Virtually every one of us agrees that you could do those things to save a show. But, virtually every one of us ALSO agrees they this should never be done for anything other than a Band-Aid measure to get you through until the repair man can come.

The law of large numbers is working against you. You might not have a catastrophe THIS time but the consequences of a catastrophe are often so great that you can't afford to have even ONE.

Don't take chances. Don't roll the dice.

Posted by Christopher Meredith (Member # 3767) on 05-22-2007, 11:01 AM:

quote: "Chris Slycord"
But as was mentioned, just detaching the blower stack from the unit will probably let quite a bit of the hot air out. Anyone knows that hot air rises. So some of it will tend to shoot up simply from convection. Plus, inside the lamphouse the air pressure will be much higher than outside which will cause the air to tend to go out any opening.

You should definitely try that before doing anything more involved, especially if your lamphouse sucks in cool air from a lower section than where the hot air will be let out.

I think it goes without saying that if I had it to do over again, I would do that instead. I posted here precisely for this kind of feedback. So thanks!

Posted by Dominic Espinosa (Member # 2122) on 05-22-2007, 12:11 PM:

quote: Christopher Meredith
But if the bulb is operating at proper temperature and the hot air is sufficiently removed from the environment in such a way that there is no greater risk of the bulb spontaneously exploding in my rigged setup than there is in normal operation, then I hardly have to worry about what happens if the bulb explodes. Why would it? It only has ~250 hours on it and is being run at proper current levels.

Bulbs can fail sitting on the shelf (LTI anyone?). You should never assume that any one bulb will last any amount of time.
This is the reason for safety gear even with new lamps.
The more stress (heat) it gets the faster it'll fail and all that heat does nothing good for the seals.

Posted by Richard May (Member # 2627) on 05-22-2007, 12:40 PM:

I guess I'm just so used to theaters running with no booth exhaust or any kind of fan on top of the lamphouse to think it's a serious issue. These theaters all use 1600,2000,3000, and 4000 watt bulbs. I have never heard of any exploding. Obviously they ALL should have exhaust but I'm never worried working around them while they are on. They all do have the covers on though so nothing is going to come out if something did happen. A lot of these people just don't understand that the exhaust is needed. Also, if they have never had a problem without it, they arent going to spend the money to do it. Again, I'm not saying it's the right thing to do. I'm just saying that it's done A LOT.

Posted by Monte L Fullmer (Member # 2797) on 05-22-2007, 01:27 PM:

quote: Dominic Espinosa
Bulbs can fail sitting on the shelf (LTI anyone?)....

and speaking of them damned things, when a LTI blows in the carrier, those three velcro straps doesn't hold the case together worth poop, plus the cheap plastic that is used in making those carriers shatters just as bad as the bulb does.

This is all due to the increased pressure (cold) that is installed in those bulbs...

Posted by Paul Konen (Member # 41) on 05-22-2007, 01:29 PM:

I will just say this that the booth should have at least one inline duct fan to use in this type of situation. You can have the exhaust blow into the booth or let it go into the ceiling if you have a drop down ceiling.

It has saved me a couple of times when the roof exhaust went down and it saves your show schedule.

Posted by Jack Ondracek (Member # 1466) on 05-22-2007, 10:08 PM:

Yeah... I think Chris gets the point. Asking for opinions here is like drinking from a fire hose.

I'm glad you took the feedback the way you did, Chris... even if the prevailing suggestions weren't your first choice.

Posted by John Wilson (Member # 269) on 05-22-2007, 11:57 PM:

quote: Jack Ondracek
Asking for opinions here is like drinking from a fire hose.

That's the funniest thing I've read all week. [thumbsup]

Posted by John Pytlak (Member # 331) on 05-26-2007, 10:00 AM:

Venting directly into the projection room does carry a risk of exposure to ozone. Although most modern lamps are "ozone free" during operation, ozone can still be generated by the high voltage ignition. If you smell ozone, don't run the lamp until you get proper venting.

Posted by Steve Guttag (Member # 268) on 05-26-2007, 10:33 AM:

While I suppose Ozone may be a risk and it definately affects some more than others. Most A/V projectors, even with xenon lamps don't have exhaust stacks and they will vent into the room and present its full heat load to the room.

I bigger risk is the unfiltered UV exposure. You'd be amazed how fast one can get a sunburn if their skin is in the direct path of xenon light...and I'm talking just a few minutes.

Steve

Posted by John Pytlak (Member # 331) on 05-26-2007, 11:50 AM:

Breathing even small amounts of ozone can have adverse health effects. Better to be safe than sorry.

Dying of cancer makes me more aware of all the potential carcinogens I've been exposed to during my life.

And a UV burn increases the risk of skin cancer.

Posted by Marc Hansen (Member # 705) on 05-26-2007, 12:18 PM:

quote: Steve Guttag
I bigger risk is the unfiltered UV exposure. You'd be amazed how fast one can get a sunburn if their skin is in the direct path of xenon light...and I'm talking just a few minutes.

No kidding, I do a lot of tig welding and if I'm not carefull I get sunburns thru my clothes.
Marc

Posted by Frank Angel (Member # 248) on 05-29-2007, 09:34 PM:

OK, forgive me if I add a bit more water to the fire hose (Jack, that was PERFECT!), and Chris, this is not just reemphasizing what you've already heard, I think you understand now the reason for our somewhat passionate concerns -- anyone who has seen how distructive bulbs are when they explode -- taking out eyes, even severing arteries -- knows that you have to have as much respect for them as you would handling a container of nitro -- but here's something from a slightly different perspective:

When situations like this come up, and they always will when equipment and man are put together in the same environment -- rather than risk injury to people, let the risk be to the equipment. In this case, if management demanded that the show be kept on the screen at all costs, then just let the cost and risk be to the damn equipment -- let it run as hot as it pleases and whatever happend from that point on, so be it, but it will be to a bulb exploding inside a contained lamphouse, not out in open air. Run it safely from the standpoint of the personnel who need to come in contact with it and if the thing finally fails, hey, then it fails with no harm to anyone except its own innards. If management wants to accept risk, let it be to his lamphouse, not his workers.

Someplace on here there is a picture but I can't find it at the moment, of an exploded bulb and what the lamphouse looks like after the event. I have copies of it pasted up on the walls of our xenon followspots. It's a very effective motivator preventing the young operators from giving in to the temptation to futz around with the lamphouse and the interlocks. Too bad we don't have that picture of the guy's face with the shards of quartz protruding out of his forehead, neck, cheeks and severed nose.

John P., what was that great line of yours?...."And the last thing the projectionist saw was the xenon bulb exploding" ?!!