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Can Fog/ Haze/ Smoke Machines Set Off Fire Alarms? Here’s The Truth!!

Will a fog machine set off smoke detectors? Is a fog machine safe indoors? We reveal all...

Fog and haze machines are usually seen as a first class ticket to setting off a smoke detector, or worse, a set of sprinklers! A reputation that’s understandably given this pair of atmospheric effects a bad name. So much so that DJs and venue hosts alike, are often anxious about using foggers or hazers altogether, in case they upset the air balance and trigger a fire alarm.

But with that being said, doing so is actually quite rare. And that’s because providing you’re clued up on your equipment, as well as the different types of fire detectors, avoiding this ‘alarming’ possibility, is actually pretty simple. Nothing you can’t learn in 5 minutes.

Plus, these detectors aren’t all a sensitive as you might think – 99% require a lot of fog to be set off! So really, getting all anxious over it just isn’t worth it. With that in mind then, what’s the difference between fog and haze machines? And how do you prevent them from setting off fire alarms? We unravel this conundrum…

After something specific about smoke detectors, fire alarms or any other performance worries? Use the menu below to get clued up on the ‘Fog machine VS smoke detector’ debate in record time…

fog machine sat next to a hazer

NOTE: If you’re looking to buy a fog machine, also be sure to check out our rundown of the Most Popular Foggers.

Before uncovering whether fog or haze machines can actually set off fire alarms, it’d first be wise to define the difference between a haze and fog machine. Otherwise, you may find yourself setting off a detector without realising it. Not good news! So read on for a summary of the differences, as well as some of the similarities between fog and haze machines…

Differences between fog and haze machines

1: How they create atmosphere

One of the most notable differences between fog and haze machines is how they go about creating an atmosphere. Typically a haze machine will be the more relaxed of the two, as unlike most fog machines, its doesn’t blast out clouds of atmosphere at full pelt. Turn on a haze machine and the atmosphere will seep out very gradually, opposed to being concentrated. Therefore, while a fog machine is a quick solution, the haze machine creates by far the most even haze. The type of subtle atmosphere you’d want at a formal event, whereas a fog machine creates jets of fog you’ll more likely expect at a music show.

2: Fuel type

Despite fog and haze machines both creating an atmosphere, the fuel they use is slightly different. Your typical fog machine will be powered by a water-based fluid that’s mixed with glycol. Whereas most haze machines will rely on an oil-based fluid, which is typically more expensive to buy. That being said though, haze machines are usually more economical on fuel, so the cost does even out. Equally, there are a select few hazers that run on water-based fluid, in which case they’re known as fazers.

3: Type of atmosphere

The main difference between fog and haze machines is the type of fog. With the water-based fluids, the actual atmosphere that’s created is quite heavy, so within a couple of seconds it’ll sink to the ground and evaporate. However, with the oil-based fluids used in haze machines, the particles in the atmosphere are far lighter, all of which means they hang in the air for a lot longer. If you’re after an atmosphere that compliments the beams of your strobes or lasers, then this is the option to go for.

a cloud of fog

4: Amount of residue

Although both fog and haze machines do leave little in the way of residue, because of the water content in the fuel, this is something you’ll typically get more of with a fog machine. Something you don’t tend to get with a haze machine, due to the particles being so light. In fact, in order to even get a residue from a haze machine you’d have to maintain a haze constantly for around a day!

5: Susceptibility to movement

Another key difference in the ‘fog VS haze machine’ debate is how susceptible it is to movement. So by that we mean how robust the atmosphere really is. For instance, with the water-based fog fluid used in fog machines, your atmosphere will likely get swept away with a few quick gusts of wind. Whereas, with haze that’s less the case. A cloud of haze is far more hardy and therefore if you ask us, ideal if you want a long lasting effect. Whereas fog is more a one-time impact that you shouldn’t expect to stay around too long outdoors.

6: Warm up time

A major perk of haze machines is that your average machine does not require any warm up time – they’re simply plug-in-and-play. Reason being is the way they actually create their haze. Unlike fog machines which cool liquid to turn it into particles, haze machines use a spray pump or Co2 to force fluid into fine particles, much like an aerosol.

7: Reaction to light

Any atmosphere generated via a water-based fluid is going to react a lot different to a haze generated from an oil-based fluid. Reason being that oil particles react far more to light than water-based fog, and therefore are ideal for complimenting DJ Laser Lights and strobes. Whereas with fog machines you don’t get this affect. The majority of the fog that’s actually produced is opaque and therefore water-based atmospheres more disguise your lighting than compliment it.

machine creating fog next to smoke alarm

While you can never really say if a haze or fog machine will set off a smoke detector (or worse, sprinklers), that’s not to say that you can’t predict if it’s likely. After all, factors like the type of venue, as well as fuel and even how heavily it’s applied can all influence the likelihood of triggering an alarm. Saying that though, one of the main ways you can gauge this is by the actual smoke detector itself. Therefore, here’s a quick rundown of the types of fire alarms that you can expect to find at venues around the UK…

Alarms that detect heat

With fire being a HOT thing in itself, there’s a good portion of alarm systems that detect heat. So if there’s a noticeable change in the air temperature, then this type of alarm will sound. However, this shouldn’t present too much of an issue with fog or haze, as (providing you use it sparingly) the overall temperature of the room shouldn’t change that much. If you come across a venue with one of these, we wouldn’t be too worried.

Alarms that detect a change in atmosphere

This is the type of alarm to be on the lookout for, as especially with fog machines. Reason being that if a large cloud of dense fog drifts within close proximity, then it’ll likely cause the alarm to sound. But it’s not all bad news with this type of alarm.

In fact, if you use haze it shouldn’t be too much of a problem. This being because the haze particles are far less dense. Plus, use it sparingly, which just also happens to be how you get the best effect, and there should be far less particles in the air too. So even though this is the most common type of fire alarm, choose your kit wisely and it shouldn’t present an issue.

a red siren that's been set off

When DJing for a party, rave or even a wedding where the action’s indoors, the last thing you want is for your fog or haze machine to trigger the fire alarm, or worse, the sprinklers! However thankfully, there are fair few ways in which you can prevent this rather sorry predicament from happening. So to help you decrease the chances of this rather unfortunate scenario, here’s a few tips on how you can prevent a fire alarm from sounding…

  • A venue checkup – Probably the easiest way to prevent an alarm sounding is to do a pre-venue checkup. That way you can test out your equipment beforehand and negotiate with the venue hire to see if you can get some of the alarms turned off. In our experience, that’s something a lot of venues are completely fine with, although if they do object, you can also propose to them the next option…
  • Get yourself a fire marshal – In the case a venue is a bit funny about you disarming some alarms or even using fog/ haze full stop, you can always get around it by hiring a fire marshal. This is essentially someone who’s responsible for turning off the alarm if it should sound unexpectedly, or ushering people safely out of the building in the case of an actual fire. Good thing is, most venues won’t quibble if you were to switch alarms for a fire marshal – if anything they’d be over the moon. Reason being that doing so actually make them look a lot better in terms of insurance. Useful to know!
  • Ask yourself if atmosphere is even needed – While atmosphere in most cases does give a nightclub or concert that extra edge it needs to feel special, that’s not to say it’s always necessary. Take an event like a wedding for instance. While a great big cloud of ground fog would look ace creeping down the isle, it’s by no means a ‘must have’, especially if could cause the bridal party to be drenched in fluid from a fire springer. That’d be one soggy bride – yuk!
  • Change up your equipment – It’s worth noting that one piece of equipment doesn’t suit every space. Fog machines for instance come in various wattages, and can project their fog across a whole variety of distances. Some just a couple of metres, whereas other can touch on 8! All of which means that changing up your equipment may be solution to not triggering a fire alarm. Have a fog machine that can spew out high volumes of fog and chances are that in small spaces, the news won’t be so great.
  • Be gradual about it – When planning an event with atmosphere, ideally you don’t want to rush. Not only does that make life more stressful for you, but it also means that your atmosphere will likely be less constant. And that’s the key, especially with haze. We’d always recommend leaving your machine on for around an hour before the event begins. That way the atmosphere can gradually build up across your event space and therefore should be far less of a rapid shock to the smoke alarm.
venue staff checking safety gear

The short answer is yes – both haze and fog machines are safe for use indoors.

As for the fog itself, both oil and water-based fog fuels are non toxic. So inhaling fog from either of these machines is nothing to worry about. And as for conditions under-foot, these fuels only really condense if they’ve been used excessively without ventilation. So providing you keep windows open or setup the air con, there should be no real slip hazards to report.

And while both hazers and foggers do their job at creating an atmosphere, if it was a toss up between one or the other, we’d choose the hazer every day of the week. Not that there’s anything wrong with fog machines – they do create a good affect, especially at music concerts and clubs. However, a hazer just seems to 1up it in most areas.

For starters, because of its lighter particles, it makes for a far more subtle affect, which should make it kinder to fire alarms. What’s more, because of its metallic quality, it also allows DJs to make more of a feature of their strobes and lasers. Not only that but it lasts for longer too, making most hazers more economical when it comes to fog fuel.

Then factor in that unlike with a fog machine, oil-based hazers don’t have a warm up period and it’s pretty much a home run. In fact, the only real brownie points that fog machines have over hazers (in our opinion) is the price. Hazers typically set you back 2, sometime 3 times as much. However with that being said, factor in all the advantages above, and as an investment, hazers definitely pay you back.

All of which makes them a cost that we think is worth footing, as well as piece of kit that’s less likely to set of the smoke alarm. A ‘2 in 1’ if you ask us.

Enjoy discovering how to prevent fog machines setting off fire alarms? There’s plenty more where this came from. Don’t miss out on all our latest DJ Equipment Reviews, as well as the lowdown on all things Music Production. Recently, we also did a review of the Best Studio Monitor Speakers + another of the Best Guitar Pedals EVER, which may also be useful if you’re playing live.

a party with a lot of fog

Or continue reading to learn even more about fog machines, smoke alarms and sprinklers…

No – smoke from a fog machine isn’t bad for you!

From what scientists can tell there’s near to no impacts of fog fuel on the human body, even with those who work with fog and haze machines for a living. And while water-based fluids do include glycol (some forms of which are toxic), the ones used in fog fluid are clean and perfectly fine for humans to breathe.

For those scientists among you: In fog fluid you’ll find propylene glycol, which is non toxic. Ethylene glycol (ie antifreeze) is its toxic cousin.

Nope, they’re not.

The main difference between a fog machine and a smoke machine is how they produce atmosphere. Smoke machines use heat and give out a hot slightly sweaty-feeling atmosphere, whereas what’s known as low fog machines produce a cold liquid (usually using dry ice or co2), to create a low-lying cold atmosphere.

Low-lying atmosphere is often used on stages to create a ‘walking on water effect’, while the more heated atmosphere of a smoke machine is used to produce jets of fog that shoot up along the stage at major pop concerts.

One of the easiest ways to tell the difference between the two is to watch what happens to the fog that’s produced. if it rises then it’s come from a smoke machine, yet it it falls to the floor it’s come from a machine using ice. Hence why low lying fog machines are designed to go on the ground.

In most cases, no.

Throw a match into the middle of a cloud of water-based fog (water & propylene glycol) and there’ll be no explosion or massive inferno. However with that being said, propylene glycol is known scientifically as a slightly combustable liquid, which you’d be wise not to use near sparks or an open flame.

And it’s much the same with oil-based fog fuels, which contain either glycol (above), glycerin or some sort of mineral oil. Now while typically your mineral oil shouldn’t be flammable, it’s worth noting that glycerin is. But it’s worth remembering that in all foggy situations the concentration of these chemicals is so fine that an open flame shouldn’t cause much in the way of drama.

The only real reason to be wary of this should be when fuelling up the fog machine, as the fuel is far more concentrated. Then again, if you are going to light up and have a cigarette, we’d still encourage you to do the sensible thing and do so when you’re not in a cloud of fog.

It’s just common sense really.

No – dry ice should not cause your smoke alarm to go off.

Reason being that most alarms detect particles and changes in the overall atmosphere. Something that using dry ice doesn’t change, as it’s simply carbon dioxide in its solid form. And as you all know from GSCE Chemistry, a good chunk of air is Co2, so unlike with smoke, it’s not seen as an air pollutant (i.e. threat).

Plus, smoke from a dry ice machine falls to the ground and stays there. Its nickname is ground fog. So as you can imagine, it gets nowhere near a smoke alarm, which 99.99999% of the time are located on the ceiling. Reason? Unlike dry ice, smoke rises.

Ice – that’s the secret ingredient if you want your fog to stay low.

Now we could go onto describe how and get into the physics of things, but instead we’ll just let you see for yourself. Click the video below to watch this creative soul create his very own ‘chillbox’ fog machine that takes normal upward-rising fog and makes it sink down to the ground…

YouTube video