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Do Flares Work Underwater? Clear the Doubts in Easy Way

We use flares for indicating signals, illumination, and in some cases, defensive purposes. If you feel threatened by something or need to warn others, you can use emergency flares to deliver messages. In some cases, if you use emergency flares correctly, you can channel traffic for various reasons.

But do flares work underwater as well? Yes it does work. But if you wanna know the actual process, you need to read the full article. Because, having half knowledge about something isn’t a good practice at all.

I was always having this confusion while growing up. So today I will explain it to the core so that you can get a clear cut answer.

do flares work underwater
Do Flares Work Underwater?

The need for flares comes under the water as well, be it communication or to notify others to rescue. Flares are effective for these types of purposes.

But before that, you need to know, do flares work underwater and how. So let’s read more to find out!

Do Flares Work Underwater?

Yes, flares can work underwater. 

But there is a certain flare available to use underwater. Flares generally work underwater by the principle of oxidation. You might know that a type of element called alkali metals reacts typically with water violently.

These elements are in place of the standard substance used in emergency flares used on land. 

Specifically, one element is present in underwater flares: calcium, which burns without any reaction with water.

How does it work?

To make an underwater flare, you need to supply both the reacting substance and the element which oxidizes through a channel. This is because there is no availability of free oxygen in the water.

The reactive substance can be hydrogen or acetylene. Depending on the pressure application, accordingly, the flare will work.

Now, to stabilize the flame, a bubble needs to be present around the flame, and it has to steady which the gases (water vapor or carbon dioxide) that come from the flame cannot provide.

Therefore, the gas needs to be supplied at high pressure to overcome the pressure exerted by the water. That is why divers need extra jets of compressed air to protect the flame when in need.

Emergency Flares and Road Flares: Are They the Same Thing?

To answer your question, no, emergency flares and road flares are not the same things. But they don’t have a big difference as we know both can be waterproof.

The fundamental difference is, we use road flares to control traffic or in a scene of an accident to warn other people while driving. They are typically used at night time and therefore not proper for daytime use.

Whereas emergency flares during a life-threatening situation. If lit, it gives a bright light and releases a vast cloud of toxic smoke which is not suitable for health if inhaled for a long time.

For example, in situations like rescue indicators or to pinpoint a location, it is used. These can be hot enough to melt tires, blind the traffic, and lead to accidents.

Do Flares Need to be Waterproof?

You need to understand that all flares do not need to be waterproof. However, some emergency or road flares claim to be waterproof. This means you can light it during rain, seashores or even underwater as well.

However, all flares are waterproof as it is an essential need during survival circumstances. Some of the flares can get damaged due to rain, humid weather or after being submerged.

The reason behind flares being waterproof is that these flares use o rings to seal the top and are created particularly for divers and underwater reasons.

Types of Emergency Flares

Generally, flares have two main functions. First, they are used to send signals or deliver messages. Second, it also helps to indicate the person’s position so that the rescuer can help. There are usually three types of flares:

Handheld Flare

These types are very effective as they are very bright and have a good visibility range both day and night. It is used as a distress signal and is visible for at least seven miles on a clear night. The candelas measure up to 15000 approximately and burn for 60 seconds maximum.

You can use it as a warning or to alert people. For instance, if the boat is new to the shore, you can send a signal to indicate the captain. Or you can pinpoint your position during a rescue mission. To use it, you need to check the flare.

The side of the flare mentions how to use them. But always make sure that the flare is away from the operator’s eyes and should be held above the head and downwind tilted.

Smoke Flare

As the name suggests, when lit or triggered, it releases a cloud of smoke. They are effective only during daylight. This is because smoke is not visible clearly at night.

They come in two types: handheld and buoyant. The visibility range of this flare is up to 3 miles approximately, and the handheld burns for 50 seconds while buoyant stays up to 3 minutes.

You can use this type of flare when you want to be rescued or send the location of your place. For instance, if you wish the aircraft pilot to indicate the direction of the wind, you can use this flare. Make sure not to use it at night.

Handheld ones generally come in red. To activate the buoyant, you need to throw it in the direction where the wind is not affected and visible to the rescuer.

Parachute Flare

This flare can attract attention during daylight and can be visible upto 28 to 30 miles at night. The height of the flare while triggering can go upto 300 meters and measure up to 30,000 Candelas. It stays for 40 seconds and is suitable for alarming the rescuers or warning purposes.

Note: Do not use it if there is a helicopter or any aircraft over you.

How to Properly Store and Care Your Flares

If you are worried about the storage of the flares, then I got your back. The flares are usually safe and stable to store at your house or in your garage. We know, officially, flares as flammable solids, but they are not sensitive to the initiation process. There is no danger of explosion or any threat for individuals.

Even after this, there is always a chance to experience some life-threatening situations. If not kept correctly and with care, it can cause a mass explosion. Therefore we must keep them in a safe place and away from crowds so that in some unfortunate cases, fewer or no people should suffer.

So how will you care for your flares?

  • We should store the flares in cool and dry places. The low temperature keeps the flare cool and more stable.
  • The flares should be always from excessive heat zone or area ( approximately above 75 degrees Celsius)
  • One should not expose the flares to water for an extended period. This can damage the substance present in the flare and later explode.
  • Generally, flares do not have any expiration date, but if it is in a very low temperature for a very long time( say more than two weeks). Then it is recommended to dispose of it properly.

Are there any Alternatives for Emergency Flares?

Nowadays, there are a lot of alternatives to traditional emergency flares. One of the effective flares is an LED visual signal device.

The standard flares can easily replace this device as it is battery operated and lightweight. It can last for hours; on the other hand, flares only last for minutes. It can also be used underwater and have a visibility range for up to 12 miles with a pathway of two to three miles wide.

Some electronic flashes like ACR ResQFlare have an inbuilt Morse code for SOS, are waterproof, and have floatable capacity. It can work uptown 20 hours in just one charge. It offers 360-degree visibility for more than six to seven miles. Easy to carry and store, it is not flammable at all.

Therefore you can keep it without worrying about a mass explosion. It is worthy of a one-time investment that will provide several years of service.


Get your all questioned answered here:

​Can you light a flare underwater?

Yes, you can light a flare underwater, but you need a particular type of flare. A typical flare contains substances that get affected when lit underwater. Elements like magnesium or acetylene, if present then can be used as an underwater flare.

How long do underwater flares last?

Usually, an underwater flare lasts 1 to 2 minutes, depending on the flare. Handheld flares last up to 60 seconds, parachute flares last up to 40 seconds, whereas smoke flares stay up to 50 seconds.

​Are road flares waterproof?

Nowadays, most road flares are waterproof. This means it can be lit during rain or beside a rough sea and sometimes even under the water.

​How to dispose of expired flares?

To dispose of the expired flares, you need to store them in a watertight container and keep them in a cool and dry space. It is advisable to call the fire department or any local police department to dispose of the outdated ones.

​Is it legal to set off a flare?

We know flares are quite explosive; therefore, always seek advice from the authorities. And in emergency cases, it is legal to set off a flare but not dump it beside the sea range.

Final Thoughts

Now we know the working of the flares and what those types are. Yes, if you are wondering, emergency flares do work underwater.  This helps you to test the flares to know if they are effective or not. Just make sure to hold the flare vertically if you want it to work correctly. 

So stop searching “do flares work underwater” every now and then, as I hope this article clears your doubt about it. Do let us know!

Rocky D

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