What causes flares to go out of date?

[Coaster]

Over the years I have run many many flare session for students. It used to be common practice for instructors and their students to fire out of date flares on sea survival courses, on several occasions we fired off flares that were 10, 20 and more years old, occasionally some failed to ignite, and some wee a bit discoloured but the majority worked fine.

Following a fairly well published accident in 2006 involving a white hand held pains wessex flare instructors have re considered how they run flare sessions. Despite firing hundreds of out of date flares for years with no harm and despite the fact that the accident occurred using an in date flare we all came to the conclusion that we should only use in date flares for demos.

I am not convinced now that we use in date (but sometime nearly out of date) flares that the number of flares that fail or are discoloured are any less than they used to be.

Thanks for that excellent post. It's informed opinion and information like this that makes these forums worth a great deal.

I shall continue to store my flares carefully, renew them periodically, and keep them on board until they're about 8 to 9 years old, thus having spares in the event or a serious problem.

 

[maby]

One of the sailing magazines ran a test of TEPs a few months ago - can't remember which, but assume it was either PBO or Yachting Monthly since those are the only two I buy with any regularity. If I remember correctly, they found that the majority fired exactly as specified, a small number misfired in various ways, but none were actually dangerous. The majority were only a few years out of date, but they did check a few that were long past their sell-by.

 

[Ricd]

To answer the actual question, it's about the stability of the contents. They can trust the contents to be safe up to a point, despite how they are stored, only for a period. Some flares might be stored better, not subjected to extremes of temperature, but the manufacturers have no control of storage conditions on board, so they try to second guess what you might to with them, and come up with a safe period based on their knowledge of what might happen. Even then, they are making assumptions that you don't store them in the middle of a log fire etc.

I have been told that it is the MCA (certainly their equivalent in US) that set the expiry date for emergency pyrotechnics and that the manufacturer only follows their advice. I would assume that if the manufacturer set an expiry date, as with food, it would be based on their recommended (practical and reasonable to expect) storage conditions with a earlier expiry date to allow for a margin of error hence my original question...how long can they last if properly stored?. Can anyone comment on the MCA input?

 

[KAM]

It's the Arrhenius equation. This relates rate of chemical reaction to temperature. The chemical reaction in question is that causing the pyrotechnic ingredients to degrade. The equation has an exponential term which means a small increase in temperature vastly speeds up the reaction. Manufacturers have to design flares to perform to specification at high and low temperature extremes after having been stored in bad conditions and roughly handled. Possibly stored for years at high temperatures. This determines the manufacturers expiry date. I doubt if the MCA has any input to this process. Flares expected to be used in benign UK conditions say between 0 and 20C and stored at an average of 10C will last very much longer than the manufacturers life. I have fired quite a lot of old flares up to 25 years old. The only problems were a percusssion cap failure on a hand held flare and failures on pull string type igniters which seem to be particularly unreliable. However now that we have cheap EPIRBs ,AIS, and DSC carrying flares seems to be pointless. I would be interested to know when someone was last rescued by using a flare only.

 

[FlyingDutchman]

I think Brendan is right. The problem is in the stability. A propellant is unstable, even under normal temperatures. For this reason a stabiliser is added. The stabiliser is used up over time and when there is no stabiliser left, the stuff becomes unstable.
Now, the speed of the consumption of the stabiliser depends on the temperature, the higher the temperature, the higher the stabiliser consumption. A manufacturer will assume a storage temperature profile and perform (amongst other tests) temperature cycling tests. The stabiliser content is measured. This is how the shelf life is calculated.

If the storage conditions are better than the manufacturers assumption, the actual shelf life will be longer than the the manufacturers statement. Problem is, we don't know the manufactures assumption so we don't know if we store them better or worse. Normally we store them better since the manufacturer will assume a worst case scenario. This means that the stated shelf life is safe. How much longer the flares stay safe is difficult to say!

I think it is a bit too easy to state that the shelf life indication is there to increase the profit of the manufacurer. Also bear in mind, that the manufacturer is responsible for the safety of the products.

edit: Arrgh.. KAM was faster!

 

[Ricd]

Have just found the USCG Guidlines and regulations relating to emergency pyrotechnics and pasted relevant section below. If I were a flare manufacturer I would take this guidance as pseudo legal/best practice and apply it to all irrespective of any internal durability testing.

Marking. (46 CFR 160.021-5, 160.022-5, 160.028-5, 160.036-5, 160.037-5, 160.040-6, 160.057-5,
and 160.066-9)
Each [pyrotechnic device] shall be legibly marked or labeled with the following, as appropriate:
Company name, location, and brand or style designation
Type of pyrotechnic device
Intensity in candela (for flares only)
Burning time (for flares and smoke signals only)
“Use Only When Aircraft or Vessel Is Sighted.” (for flares and 3-min smoke signals only)
“Approved for daytime use only” (for smoke signals only)
Simple operation instructions (in paragraphs or pictographs)
Expiration Date (month and year to be inserted by manufacturer – not more than 42 months after
date of manufacture (48 months in the case of line-throwing appliance components
containing pyrotechnic material))
Date of Manufacture (Month and year to be inserted by manufacturer)
Lot No. ----
Serial Number (for signal pistol and line throwing appliance only)
U.S. Coast Guard Approval No. ----.

 

[KellysEye]

>You really can't UNLESS you are "a concerned member of the public who has found them discarded in a public place" if you get my meaning... And then, only certain police stations are equipped

I disposed of some at a police station and was asked if I had found them. I said ''no they are off my boat'', it wasn't a problem. I did say only the large police (usualy County but more in London) stations will take them because they are the only stations equipped with a lead lined box.

As was posted Hampshire police take them as do the station where I lived in north London. If your County doesn't take then I'd ring the nearest other Counties to check if they do.

 

[status]

> snip ....only stations equipped with a lead lined box.

Why do they need a lead lined box? Is radioactivity involved?

I would have thought a steel expolsives safe would be the criteria?

Stuart

 

[VicMallows]

I would be interested to know when someone was last rescued by using a flare only.

I'm quite sure that there will be many examples (surfboards; dinghy sailors; etc). You need to add the rider ".....who had not been able to communicate with the CG by VHF or mobile phone and did not have/could not use an EPIRB/PLB....."

Vic

 

[HinewaisMan]

Back in Melbourne (Aus), we had “flare shoots”.

Twice a year, just before one of the big inter-club races, you could let your flares off within a designated area. It was spectacular, with not just all the boats burning off hand-helds, but over a hundred para flares hanging in the sky.

Not only did it alleviate the problem of out-of-date flares, but people actually learned what it was like to let a flare off before they have to do it in a high stress panic stricken environment.

I wonder how many readers have ever let a flare off?

No doubt in the namby-pamby PC H & S idiocy that the UK has become, such a sensible idea will never be possible.

 

[VicMallows]

Back in Melbourne (Aus), we had “flare shoots”.

Twice a year, just before one of the big inter-club races, you could let your flares off within a designated area.

No doubt in the namby-pamby PC H & S idiocy that the UK has become, such a sensible idea will never be possible.

Precisely.

Vic

 

[prv]

No doubt in the namby-pamby PC H & S idiocy that the UK has become, such a sensible idea will never be possible.

The training folks based at my yard regularly let off hand flares from the Travelift slip, presumably as part of courses.

Pete

 

[grumpy_o_g]

Why do they need a lead lined box? Is radioactivity involved?

I would have thought a steel expolsives safe would be the criteria?

Stuart

I didn't know they used lead and suspect radio-activity is actually the reason (in the 60's and 70's the authorities had this idea everyone would be finding radioactive items for some reason). Weight is the main factor, plus a soft or malleable nature so lead wouldn't be bad except that you could end up with lead shrapnel flying around. Water and sand can be excellent dampeners (not if you're in the water of course) because the energy is unfocused. Steel and such is fine if you know it will contain the blast completely. If doesn't it will simply allow a greater pressure to build up until some point gives way first creating what is effectively a shaped charge with the probability of the shrapnel adding fragmentation to the characteristics.

 

[RAI]

Lead is used because it doesn't produce sparks when struck with another object. Steel would be a very bad idea.

 

[BrendanS]

I wonder how many readers have ever let a flare off?

No doubt in the namby-pamby PC H & S idiocy that the UK has become, such a sensible idea will never be possible.

I've been to at least three flare training sessions, where we let of live flares. Run by club, with coastguard or RNLI trainers. They let the coastguard know, and check just before, and if there are any 'live' hazard to life situations, they may cancel, but usually just get on with it.
Letting off flares is a great idea under these conditions, as they take care of H&S issues, but let you let off all sorts of different flares, not just the type you may have on your own boat. Brings to the fore the issues with letting off some of them, and always a metal bucket to douse the handhelds, with a warning about them burning through the bottom if still alight. It taught me many things, not the least to have a thick glove in the flare container, and what the consequences are from not hanging the flare over the downwind side of the boat, as the molten dregs will set light to most things, and how bloody difficult some of them are to set off if they need a good 'slap' first, which many of the women only accomplished by banging it on a heavy object, rather than with their hands