Rank: New forum user 
|
Hello All Looking for advice regarding down daught extraction benches. We recently had a down-draught bench installed but were advised it is not suitable for lead fumes. We perform lead-free soldering and oxy-acetylene cutting, so good enough for me. The bench has two drawers at the bottom for the removal of dross and waste materials. However, the management now want 'case hardening' to be performed on this bench. The process emits toxic fumes including free cyanide and hydrogen cyanide. Why is this bench not suitable for lead fumes and would it be safe for the cyanide and hydrogen cyanide gases?
|
|
|
|
|
|
Rank: Super forum user
|
Have you spoken to the manufacturer of the bench? My own view from my experience with these is that it will depend on the type of filtration that is fitted. I find that most have some form of activated carbon filtration that should be sufficient, but also that the advice from reputable manufacturers is usually pretty good. One thing you might do is to estimate the distance over which the bench works using some form of smoke or other visible detection method. I use one that produce a continuous stream of white vapour, ideal for practical checks of this nature. PM me with an e-mail address and I will send you information on this. This should show you the distance over which the bench can be effective so that you can reach your own informed decision.
|
 2 users thanked chris.packham for this useful post.
|
|
|
|
Rank: Super forum user
|
Lead fume is very fine lead particles and they may block the filters. Cyanide and hydrogen cyanide gas needs to be absorbed onto a carbon filter, which the lead particles might damage. To dela with cyanide gas you really need a good extraction system and what ever you use LEV for the crucial test is not that it achieves some arbitrary face velocity or level of “suck” but that it is reducing the air contaminants in the user’s breathing zone to an acceptable level. Note that the WEL for 8 hr 0.9 ppm and 15 minutes is 4.5 ppm. You will need to do some measuring to ensure that the down draught system is good enough. In a addition where does the down draught table vent. If it vets back into the room, you might simply be recycling the contaminants. Your supplier should be able to explain all of this.
|
1 user thanked A Kurdziel for this useful post.
|
|
|
|
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.