I want to show you erm 2 models that have been developed and designed and built by the Health and Safety Laboratory.
So err I’d ask my colleagues here to to start the process. What we here is a spray bake a model of a spray bake down draft booth with pit extraction so erm please do.
The filtered air comes comes in through the ceiling and out through the floor and we are using smoke to simulate the fine mist I showed you earlier. And err well let it cook for a bit and settle down and what we have here is a err a spray room same idea, that’s fine well and truly full.
OK. This is our so here’s our spray room. Now the spray room is on erm my HSL colleagues have just turned the fan on and it’s built it’s dimensionally an air airflow wise exactly as the erm as was shown in the photographs earlier on so you’ve got filters in the doors err here and here and a fan at the far end, and also there was a gap round the door jam too.
Now with any as with any spray room as I showed you earlier on when you first err turn it on not a lot happens. There’s almost no directional air movement, no clearance it just sits there err cooking. Right so we’ll leave it to cook and we’ll come over to our erm spray booth. Now erm colleague here will turn it on and what you will see is the clean air coming in you get plug flow from the ceiling.
Here comes our clean air and the car will appear and you’ll see that it clears in the centre of the booth but you also see there is a lot of air turbulence against the walls and the err the err re-circulating air against the walls is what makes for long clearance time of a spray booth.
Err you also see it clears quite quickly compared with the spray rooms, and the err these models show that erm the why we talk about when we talk about exposure in spray rooms, the exposure in spray rooms are in terms of thousands of micro grams per cubic metre of air, whereas the exposures in spray booths are in terms of hundreds. You are exposed in both of them but the exposures in those devices are very high compared with here.
OK now erm we’ve almost cleared that. Can we turn this one off now please. There is a spray room running as I talk as I do the rest of the talk erm because it takes forever for these things to to to clear.
Erm now I think we’ve got erm a label here the clearance time thanks very much. The clearance time of the spray booth is 3 minutes and 45 seconds 15 seconds sorry. And the clearance time of the spray room is 13 minutes and 45 seconds. Much much longer.