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Author Topic: Duty cycle spec interpretation  (Read 6275 times)

David Allred

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Duty cycle spec interpretation
« on: March 21, 2018, 01:48:33 PM »

I understand the standard use and definition, but what does the spec mean for a fog machine?

The max ON time is the only thing referenced.  In this case 6 hrs. 
The exact spec is "DUTY CYCLE: Not to exceed 6 hours turned on."
My assumption is for the heating element.

Some days it might be used for up to 12 hrs.  I am going to plug into an outlet timer to let it rest... but how long?  Is 30 mins enough?  I was thinking an hour would be plenty, but I would like even shorter.

Thanks.

Thanks
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Mark Cadwallader

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Re: Duty cycle spec interpretation
« Reply #1 on: March 21, 2018, 04:11:31 PM »

That's probably a question for the unit's maker; anything else is speculation (or destructive testing).  What is the make and model in question?
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David Allred

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Re: Duty cycle spec interpretation
« Reply #2 on: March 21, 2018, 07:07:25 PM »

That's probably a question for the unit's maker; anything else is speculation (or destructive testing).  What is the make and model in question?

I agree, but I have had several experiences with ADJs and Chauvets tech support where the answer seemed less than knowledgeable, or answered in such a way that lead me to believe they miss derstood the question.   Frankly,  there are so many knowledgeable souls here that know how things work or maybe had practical experience that I prefer asking here.
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Jeff Lelko

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Re: Duty cycle spec interpretation
« Reply #3 on: March 21, 2018, 08:01:11 PM »

I have yet to run into a fog machine that needs a duty cycle.  Sure, some can't fog continuously and need a reheat cycle...and many cycle their heaters on and off regardless of use, but not to the extent you describe.

What's the make/model?

I'd be HIGHLY hesitant to use a machine that must be physically unplugged or turned off every so often to avoid self-inflicted damage...or worse. 
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David Allred

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Re: Duty cycle spec interpretation
« Reply #4 on: March 21, 2018, 08:25:27 PM »

I have yet to run into a fog machine that needs a duty cycle.  Sure, some can't fog continuously and need a reheat cycle...and many cycle their heaters on and off regardless of use, but not to the extent you describe.

What's the make/model?

I'd be HIGHLY hesitant to use a machine that must be physically unplugged or turned off every so often to avoid self-inflicted damage...or worse.

ADJ Fog Fury 3000.   Their top tier fogger.  I looked at several others in their line including their low wattage ones.  They all state 6 hrs max.  I am beginning to think it is a "let's  list a 6 hr max so if they burn their house down we can say we told them not to use it for long periods."
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Jeff Lelko

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Re: Duty cycle spec interpretation
« Reply #5 on: March 21, 2018, 08:43:01 PM »

That's surprising.  I was expecting you to say a no-name eBay unit.  All the ADJ foggers I've used have a thermostat in them that cycles the heater, so I don't see what a duty cycle would have to do with anything given that they somewhat enact their own duty cycle.  Looking at the ADJ Parts website, your fogger has one too.  Very odd indeed.  I have to agree with Mark though - only ADJ can provide their rationale for this.
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Lyle Williams

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Re: Duty cycle spec interpretation
« Reply #6 on: March 22, 2018, 08:59:34 AM »

It might be that if you leave them on for a month they start to gum up.  The marketting department fix is to say "don't leave them on for a month..."
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David Allred

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Re: Duty cycle spec interpretation
« Reply #7 on: March 22, 2018, 09:28:58 AM »

It might be that if you leave them on for a month they start to gum up.  The marketting department fix is to say "don't leave them on for a month..."
:o Ha
I will contact them.  I suppose, if the answer is "It will not hurt the unit", I need to ask for it in writing.
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David Allred

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Re: Duty cycle spec interpretation
« Reply #8 on: March 22, 2018, 10:43:00 AM »

All the ADJ foggers I've used have a thermostat in them that cycles the heater,   Looking at the ADJ Parts website, your fogger has one too.

I schemed out what I interpret the fogger circuitry to be. 
Less than operating temp the thermostat is closed, passing current to heater until off temp (say 400 deg).  At 400 deg the thermo opens killing power to heater and NC relay for pump control.  Temp drops to on temp (say 350 deg) switch closes, reheating heater and opening pump circuit.
That makes sense, but what if the switch fails closed?  Would that not cause the heater to burn up? 
Maybe that is the reason for the 6 hour limit, but that could also happen in a much shorter time.
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David Allred

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Re: Duty cycle spec interpretation
« Reply #9 on: March 26, 2018, 01:28:21 PM »

I schemed out what I interpret the fogger circuitry to be. 
Less than operating temp the thermostat is closed, passing current to heater until off temp (say 400 deg).  At 400 deg the thermo opens killing power to heater and NC relay for pump control.  Temp drops to on temp (say 350 deg) switch closes, reheating heater and opening pump circuit.
That makes sense, but what if the switch fails closed?  Would that not cause the heater to burn up? 
Maybe that is the reason for the 6 hour limit, but that could also happen in a much shorter time.

ADJ says it is to prevent the heater from melting.   
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Jeff Lelko

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Re: Duty cycle spec interpretation
« Reply #10 on: March 26, 2018, 04:14:03 PM »

ADJ says it is to prevent the heater from melting.

Lovely.  While I find that hard to believe if the unit's thermostat is working correctly, there's your answer.  I take it they didn't tell you how long to let it cool for?

I guess I just struggle to see what's so magical about 6 hours...  The heating/cooling cycle on most units usually reaches its equilibrium of sorts within 10-15 minutes or so.  Certainly within the hour!  I'm inclined to think it's more along the lines of what you've already suggested - if the budget circuitry cooks you can't blame them for the unit burning your house/venue down.  Or...these units don't have a long lifespan to begin with and the duty cycle either helps limp the unit past warranty or is cited as the scapegoat if you return a dead unit 2 months later after 16hrs/day of use. 
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David Allred

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Re: Duty cycle spec interpretation
« Reply #11 on: March 26, 2018, 06:45:12 PM »

Lovely.  While I find that hard to believe if the unit's thermostat is working correctly, there's your answer.  I take it they didn't tell you how long to let it cool for?

I guess I just struggle to see what's so magical about 6 hours...  The heating/cooling cycle on most units usually reaches its equilibrium of sorts within 10-15 minutes or so.  Certainly within the hour!  I'm inclined to think it's more along the lines of what you've already suggested - if the budget circuitry cooks you can't blame them for the unit burning your house/venue down.  Or...these units don't have a long lifespan to begin with and the duty cycle either helps limp the unit past warranty or is cited as the scapegoat if you return a dead unit 2 months later after 16hrs/day of use.

I did ask why Chauvet and Antari had no such requirement.  "We have been in business longer and know better."  I asked about installing an over temp switch, but quick to say that would void the warranty.  At that point I was kind of done.
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Jeff Lelko

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Re: Duty cycle spec interpretation
« Reply #12 on: March 26, 2018, 07:03:46 PM »

At that point I was kind of done.

I would be too.  Most of my experience has been with the Rosco and Jem machines, but also have some of the older Chauvet Hurricane foggers and have used a few ADJ machines over the years.  I've still never heard of a case where you can't run a machine all day so long as it's got enough fluid to do so (nor have I ever killed a machine doing that). 

Sorry to hear this happened to you, and what's worse is that their service team was less than helpful.  I'm soon to be in the market for some new semi-budget machines myself and will definitely be counting out ADJ!
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Re: Duty cycle spec interpretation
« Reply #12 on: March 26, 2018, 07:03:46 PM »


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