When it comes to accidental fires, in the home or in the shop, most of them will start in the kitchen or due to malfunctioning machinery. What do both of these things have in common? Grease!
Whether it is grease building up on cookware or being used for cooking, or lubricating grease that will help machines resist corrosion and friction while in operation.
But what we need to know is if the grease we use in our daily life can contribute to fire risks. So, is grease flammable?
Yes, grease is generally flammable but how much so depends on the type. Grease from food can be highly flammable and difficult to put out when ignited. Many types of lubricating greases are made with petroleum derivatives and hydrocarbons that are also flammable.
What’s important to understand is that most types of grease don’t meet the strict definition of flammability. Nonetheless, lots of greases will ignite and burn furiously while being difficult to put out.
It is something of a complicated subject when it comes to fire safety, but one that is well worth looking into. Keep reading and I’ll tell you what you need to know…
The Fire Hazard of Grease Depends on the Type
For starters, know that most types of grease will ignite if they get hot enough. That being said, certain types of grease ignite far more readily than others.
For instance, bacon grease that is usually used for cooking or, negligently, sometimes allowed to build up in pans will ignite more quickly and burn more steadily than lubricating greases designed to prevent friction in operating machinery and vehicles.
Conversely, some types of those greases are designed specifically for high-temperature applications, and can withstand extremely high temperatures before even approaching the danger zone of ignition.
Pretty much every type of lubricating or industrial grease that you’ll be able to buy in North America these days will have available an SDS, or safety data sheet.
You should definitely consult this sheet for more information on the flammability, combustibility and firefighting facts concerning grease used for any application.
Kitchen grease, or food grease, on the other hand, is highly variable but what you need to know is that even though it is difficult to ignite the temperatures that will do so are easily obtained in any commercial or home kitchen, so you’ve got to be careful!
Does Grease Ignite at Any Temperature?
Yes, it will. However, pretty much every kind of grease out there does not meet the strict definition of flammability, meaning that it has a flash point, the point at which the material emits combustible vapors, of above 100°F.
But, practically speaking, most greases will still catch fire and burn. Technically, this means they are combustible rather than flammable, but in either case if you have a grease fire on your hands you’re in for a very bad time.
The flashpoint of any given type of grease is highly variable, and you’ll need to consult the SDS for it or contact the manufacturer to get more info.
Generally speaking, the flash point for lubricating greases will be anywhere between 300 °F and 700 °F or even higher depending on the application it is designed for.
Conversely, the flashpoint of most types of kitchen grease, or accumulated kitchen grease from all different kinds of foods, may have a flashpoint that is only 300°F or a little bit higher.
Especially concerning kitchen grease, be especially cautious working with open flames, blazing hot heating elements and pans left unattended as these are all common causes of grease fires.
Does Grease React with High Temperature?
Yes, most greases will react with high temperatures to a degree, although this is usually only a change of form, turning to liquid, or slow thermal breakdown.
If you’ve ever been cooking in your kitchen with bacon grease, you know if you get it a little too hot and keep it there too long, it will darken and start to taste “off” or bad. That’s what we’re talking about…
It’s the same thing with some lubricating greases: if grease is kept near the upper limit of its operational range but below the flash point, it can start to break down and lose performance.
Whether this is a problem for you depends entirely on what the grease is for and what you are doing with the equipment that it is protecting.
It’s important to understand the limits of grease when it comes to heat buildup to avoid accidental fires and also to prevent other mishaps.
Is Lubricating Grease Flammable?
Yes, most types of lubricating grease will ignite if you get them hot enough. As mentioned above, even though they aren’t strictly considered to be flammable according to scientific and OSHA definitions, they can and will catch fire.
This is because lubricating greases almost invariably contain various oils, petroleum-derived ingredients or hydrocarbon-based compounds that are all a ready source of fuel for fire.
Many types of lubricating grease won’t catch fire quickly even with the application of intense, direct heat from a heat gun or open flame, but that doesn’t mean they are incapable!
Is Food or Kitchen Grease Flammable?
Yes, food and kitchen grease is definitely flammable. Whether it’s from a single or multiple sources, grease is a significant fire hazard in your kitchen.
This is specifically because of its tendency to build up on cookware that’s used directly on or near intense sources of heat, and also because of its low flash point.
Always be careful if you’re cooking with grease, and make it a point to keep cookware and grease traps, if applicable, scrupulously clean to avoid accidents.
Will Grease Make a Fire Worse?
Yes, it absolutely will. As mentioned above, grease is a good source of fuel for any fire, and when it’s ignited, it tends to burn pretty hot, burn steadily and burn for a long time while being hard to put out.
This makes a grease fire in particular a very tricky proposition unless you have specialized fire extinguishers on hand: that’s because you cannot put out a grease fire with water!
In fact, you should never, ever try to put out a grease fire with water. By doing so, the water will instantly turn to steam and it’s likely to create an eruption that will hurl burning or near molten grease in all directions, potentially wounding or killing you and others nearby and likely spreading the fire outside.
Keep your head about you, and don’t make this common mistake if you’re confronted with a grease fire. I’ll talk more about how to combat a grease fire at the end of this article…
Is Grease Reactive with Other Substances?
Usually not. In the case of kitchen grease it typically proves to be non-reactive in any way that might be hazardous or might increase its overall fire hazard risk.
Likewise, many lubricating greases are specially designed to be non-reactive because they are more likely than other substances to be exposed to other chemicals and fluids.
That being said, there are so many different kinds of grease out there, and so many different formulations of a given type, that it’s way beyond the confines of this article to explore potentially hazardous reactions with other substances.
I said it before, and I’ll say it again now: make sure you consult the SDS on any grease you’re using.
How Should You Deal with Grease Exposed to Fire?
The best way to deal with a grease fire is to hit it with a B- or K-Class fire extinguisher.
These extinguishers are intended to deal with flammable or combustible liquids, and although we don’t think of grease as a liquid, it does meet the strict definition of one and this type of fire extinguisher will work.
These units typically employ a dry chemical, fire retardant foam or even straight carbon dioxide to help smother a fire that will easily repel and resist water.
But, if you don’t have one of those fire extinguishers or a common ABC-rated fire extinguisher you might have to try and smother the fire using a fire blanket or, if it’s a small one on the stovetop, a metal pan lid. Starving a grease fire of oxygen will typically put it out.
However, you need be very careful when you uncover it later if it hasn’t cooled down enough because it might reignite.
Just a reminder: never try to use water to combat a grease fire as this will create a dangerous steam eruption!
Tom Marlowe practically grew up with a gun in his hand, and has held all kinds of jobs in the gun industry: range safety, sales, instruction and consulting, Tom has the experience to help civilian shooters figure out what will work best for them.