CA Fumes

[andersonec]

"Ignite" is a better word Ryan, especially if a naked flame is applied, an explosion needs special conditions.

Andy

[The Bowler Hatted Turner]

The official line from the association H&S guy (that'll be me then) is that woodturners should take all necessary precautions to prevent the inhalation or digestion of dusts and chemicals. A barrier should be used, either creams or gloves when handling materials that may be hazardous to health and the correct usage of the correct PPE is recommended at all times.
      Packaging labels will tell you if a product is volatile but it will not indicate any volatility(changes) when mixed with another medium. If in doubt do not use. If you use it the rules above should apply.
  What we cannot do on this website is tell people to use PPE that is not designed for the specific purpose.

[woodndesign]

I think that saying "sawdust is explosive" is too broad a comment and is doing nothing but putting the fear of god in people who have a workshop. to make sawdust explode it must be under special circumstances and there must be special conditions present at the time and the main ones are;
1. The dust must be in a very high concentration
2. The sawdust must be 'contained' and not floating in the air and preferably under compression.
3. There must be an 'ignitor' i.e. something to initiate the explosion such as an electrical spark within the container.
There are other requirements but those three are the main ones, purely having a dusty workshop does not warrant an explosive situation. It does however point towards bad lungs. It's like sawing "Flour or sugar or fertilizer is dangerous because it is explosive" These things are in everyday use but given the same conditions they (and lots of other stuff) will explode.

We used to make very large craters with a mixture of Diesel and fertilizer.

Andy

Static discharge in ducting, hence the installation of blast gate and should I recall correctly the need for grounding (earthing) pipework. There's is more a likelihood of any fire being drawn into the extractor/filter bin.

The question was CA Fumes .. Be mindful the application is by paper/rags these need careful storage or disposal of once dried as these too can spontaneously combust. 

Cheers  David

[Graham]

Hi David. That is a good one. I was aware that oily rags have that potential and treat them with great care ( usually opened out flat and left outside, or chucked in an outside bucket of water ) but had not really thought of it with the CA paper towels.

[woodndesign]

Hi David. That is a good one. I was aware that oily rags have that potential and treat them with great care ( usually opened out flat and left outside, or chucked in an outside bucket of water ) but had not really thought of it with the CA paper towels.

Hi Graham, It's more likely as BLO is used with the CA, that as with any finish, there can be the likelihood of combustion .. until it ever happens it's unknown .. most all things are unheard of until it happens.

Cheers  David

[Graham]

I do not see BLO mixing with CA on the towels ( but will stay aware of the dangers  as the methoud I prefer the sound of only requires BLO as a first coat then just CA after that.

Which raises another issue. the BLO is just to show off the pattern in the grain....... sanding sealer does that so why use BLO ?

[Paul Hannaby]

I think I agree with Andy. Just to say wood dust is explosive isn't telling the whole story and scaremongering doesn't really help the correct message to get through. Looking at this the other way round, if wood dust was really that explosive, motors on all electrical tools would need to be sealed to prevent a spark igniting airborne dust. We already know that isn't the case.

Going back to the original question about CA fumes, I recall someone saying they were overcome by CA fumes because they were wearing a powered (dust filtering) respirator because the belt mounted air intake was sucking in fumes where they were most concentrated. Obviously they should have been using a chemical respirator but this is just an example of what using the wrong PPE can do.

Personally, I dislike CA as a finish so I never use it. Problem solved! 

[andersonec]

And I would like to clear up the issue with a 'Blast Gate' in dust extraction systems.
Blast gates are used to redirect the suction around the ducting system, i.e. shutting off the suction from one machine or machines which are not in use thereby making the system more efficient.

They are NOT used in case of explosions, you would have to be pretty quick to shut off one of these gates if the need ever arose and in any case if there ever was an explosion in the extraction system your pipework would be one of the first bits to go.

Andy

[Ryan Davenport AWGB]

Andy you are completely WRONG here, large scale extractors do have a blast gate built in near the fan incase of explosion, it's not a case of scaring people simply pointing out the facts that it's possible, maybe the wording was not 100% correct but the dangers still remain, I remember a few years ago Imperial sugar has a guy like Andy saying the risk would likely not happen as the risk is so low, BUT IT DID, and the whole place blew to bits becasue of this as was pointed out in the last H&S meeting i attended.

E.g. http://youtu.be/Jg7mLSG-Yws

I don't care how small issues are at the end of the day the dangers still exists.

[Graham]

Dear me. What have I started ?

[andersonec]

Andy you are completely WRONG here, large scale extractors do have a blast gate built in near the fan incase of explosion, it's not a case of scaring people simply pointing out the facts that it's possible, maybe the wording was not 100% correct but the dangers still remain, I remember a few years ago Imperial sugar has a guy like Andy saying the risk would likely not happen as the risk is so low, BUT IT DID, and the whole place blew to bits becasue of this as was pointed out in the last H&S meeting i attended.

E.g. http://youtu.be/Jg7mLSG-Yws

I don't care how small issues are at the end of the day the dangers still exists.

If you would like to re-read my first post I did say that substances like "sugar given the right conditions" will explode, at no time did I ever say it would not happen.
Blast gates in a normal woodwork shop extraction system are designed to shut off the pipe when a machine is not in use.

Andy

[The Bowler Hatted Turner]

The original question was regarding the extraction of CA fumes. I think it is safe to assume that all fumes in the workshop are undesirable, some more than others due to their inherent dangers,(coffee fumes for instance do not fall into that category but in the right concentration although normally pleasant could turn out to be unpleasant or even bad for you). I would remind our users that health and safety in the first instance is the responsibility of the individual and therefore not to pay too much attention to spurious comments from any sources. Although we do not have to abide by the H&SE regulations (because we are not a business employing workers)the association are happy to adopt the H&SE guidance regarding safe working practices which includes guidance regarding dust and fumes extraction. These guidance notes can be found on the H&SE website.

Regarding blast gates in extraction systems. The normal blast gates were those that were closed to prevent extraction from a machine at a  given time thereby reducing the amount of extraction pipe available should a dust explosion occur. It also served to increase the efficiency of the system. There used to be additional internal gates, similar to those used on a vent-axia with the triple drop vents that could reduce the amount of back blast but over the years these would cause more blockages and reduction of pressure that would render the extraction system all but useless  that most companies removed them.This is the one closest to the motor these days. Under normal woodturning and sanding conditions for the hobby turner in the shed there should not be a huge risk of dust explosion as usually workshops are so small as to minimise the amount of static charge that can build. For the professional turners I am sure risk assessments would have been carried out and acted on.