DMX controlled Solenoid Valves?

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Let's get one thing clear first. An attitude of "it's OK to ignore some of the rules" is exactly what leads to incidents like the Station Nightclub Fire. And so around here that immediately makes people think you're a cowboy and thus hesitant to help you. We are GIVING you our time and professional advice for no return, so to have people turn around and say yeah thanks but I'll do a dodgy just plain irritates some of us.

I'm going to disagree with Footer on the risk involved. A system with enough foce to shoot water 20 metres into the air is more than enough force to injure someone.

So let's talk about what's currently designed to be in the system apart from the DMX trigger itself...

Where is the firing location for this effect and how well controlled is access to that area?
Specifically, is this an area where during the veiwing of the dispaly there is a reasonable chance a member of the public could stray?
How does the whole display run? Is it a timer that runs at the same time every day, whether there is anyone home or not, is it manaully started, what?
Who's watching the area where the effect gets fired from to check it's safe before it goes off? What's to stop a cat or bird from being on top of the release point and how does the system respond safely? (This is one of the biggest reasons for manual deadmanning systems)
You've suggested that you might set the system to only be "armed" for a minute either side of firing time. Conceptually, you're starting down the right track, the timing seems a little wide, but how do you control this arming window? It would defeat the point if that information came from DMX, so is whatever is arming it better equiped to fire the effect itself too?

In general, what we expect to see are things like arming systems, generally with keyed switches, emergency stops in reach of the operators, dead man systems, lockout provisions and safety interlocks as appropriate to the design situation at hand...


1. Im sorry if im irritating some of you. I dont mean to. All i am saying is that i dont have the luxury to do it the code way, much like many of you may (should), and because this is a system thats at home, away from the public, the rules i have to follow are different, yet still there. I WANT to do things the right way, but that often means spending a great deal of money that i just dont have. The reason i am here to angle into the best way to get it done, the safest, and as close to code as possible.

2. This effect is located in the backyard, away from the viewing area in front. Access is gated with your standard suburb fence gates, and no one should be back there for any reason while the effect is primed. We dont use our backyard at all really, i can only name a handful in the past few years where we have. So its secure and untraveled.

3. No. Theres is no reason anyone would be near the effect.

4. Last year it was timed to start at 8:00, ending 10 minutes later, with some lights illuminated before and after the show. Effects, such as snow machines and foggers were only timed to turn on from 7:30 to 8:30, but dimmer packs were always on. It went last year whether people were home or not, though sound was off for any shows i wasnt there for. I imagine any potentially hazardous effects be the same way.

5. I mean i could be there, but i would prefer not too (note, i could also rig up a remote interface i think). This is the whole issue, where i dont believe that there is a chance that some bird or person will just be there at the wrong place wrong time, but birds would be more of an issue than people so i suppose there is a way i could keep birds off of it (i know some sort of anti-bird mechanisms exist)

6. Well i imagine i would have it timed like i did my other effects such as snow and fog, last year i simply had them on a heavy-duty timer so they would only be powered when needed, i think it would be the same for the cannon, the solenoid would only have the power available to open during 1 minute of operation (could be less or more) which means there is only a 1 minute window where it could possibly fire, and at every other time of the day it wouldnt be able to open without power. The DMX will just be the trigger, so essentially the timer will load the cannon, and the DMX will fire it. No ammo, DMX trigger does nothing.

Thanks.

I'm sorry but the fact that you are arrogant enough to walk away from the water cannon shooting water 60 ft in the air shows me only one thing. That you have no right to ever do anything involving special effects. Yes there are fountain shows that are automated bit they are not automatic. there is always a dead man switch with a worker pressing the button, anytime the public could gain access. And don't use the its my backyard they won't go there. People do things they aren't supposed to. Hence all the idiot warnings Like do not put a baby in the five gallon bucket. Never assume anything will be safe. Dmx is fine for a trigger but there Damn well better be a power kill dead man's switch with a live and observant operator.

I agree, people will be stupid. But you know what, we can play "what if" all day. What if the gas tank ruptures as explodes? What if the cannon happens to hit a bird flying mid air? You cant be prepared for every statistical improbability, and you cant always assume people are going to be the dumbest in the world.
 
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Completely and utterly agree, but why on earth would I let anyone near the thing while its primed (even if they happen to wander by it, unlikely since no one goes in my backyard)? Safety is always a valid concern, but you have to admit that someone sticking their face in front of the spout is an extremely unlikely scenario, and even for that there would be failsafes regardless of the trigger mechanism. I could make the spout too tall to reach without assistance, the solenoid could only powered when it was ready to fire, etc.

Regardless of what profession youre in, you cant always protect people from themselves. Sticking your face in front of an active water spout is as foolish as holding a 1kw lamp thats plugged in. you just wouldnt do it.

Worst case scenario... your console shuts down for whatever reason. A DMX death gasp opens the dimmer that is controlling the solenoid. Selenoid fires. Water flys. Water keeps flying. Floods your yard which is covered in xmas lights. GFCI does not function right... fire starts. At the same time your air compressor that fired the cannons is running continuously. Also overheats... fire starts. Not saying this would happen... but it could. You have something that could cause harm in some way running without watching it.

In reality, its not the DMX that really concerns me, its the 60' tall column of water your firing into the air automatically, over and over again, with no human interaction.

So, in order to do this safely, at least what this industry deems safe (which is who this website is for), you do have to have some type of conformation that the area around the effect is safe. I guarentee you go out in front of the Bellagio and jump in the fountains the show will stop because someone is watching it. They might be watching a security camera, but they are watching. Same thing goes for Treasure Island, World of Color, etc. Even the olympic rings fountain in Atlanta has an emergency stop that guests can hit to stop the whole thing. Your talking about shooting water 60' into the air. That is not just a little squirt gun. That can deal some real damage if some little kid from down the street climbs in in the dark and gets hit by it.

So, if you want to do this via DMX, go for it. You seem like you know what you are doing. But, as an industry, we have found that any type of automation needs to have the oversight of a human being in the mix, be that via a dead man, pressure pad, or other "enabling system". If you chose to go without this, its your thing. Go nuts.
 
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