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Old 3rd Sep 2004, 6:24 pm   #1
ekco1953
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Default Dealing with asbestos.

Got my first DAC90 today

There's a bit of work needed at the dropper. As many of you will know it's surrounded by soft, white asbestos. Can anyone help answer 2 questions, please?

1- Is there REAL danger working around this area?

2- can the asbestos be removed and replaced with a modern safe material?

Also has anyone any specific tips on the subject?

The usual searches bring up results like " take care with the asbestos... " and " take the necessary precautions... "

Very helpful - NOT :

Thanks
Jim

Last edited by Chris_C; 24th Feb 2005 at 5:21 pm.
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Old 3rd Sep 2004, 6:41 pm   #2
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Default Re: Asbestos in DAC90

I know. I have a PYE R33, which has a piece of asbestos glued to the inside of the cabinet. I have been putting off and putting off working on this set because I don't really know what to do - should I remove the asbestos, butt hen there won't be a heat shield for the plastic case. Where can I dispose of the asbestos, and what should I wear/do while I am removing it?

Not relavant to the DAC90, but in a wider sence, it is!

Sam
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Old 3rd Sep 2004, 7:12 pm   #3
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Default Re: Asbestos in DAC90

Heres some general guidelines, this is for Sam

Wear protective clothing ,gloves & dust mask (A respirator type not the simple fabric one)

Make sure noone is around the area of work

Avoid producing dust as much as possible

Put asbestos material into strong plastic sacks or wrap larger pieces in plastic sheeting.

Contact the council for advice on disposal : Abestos is not allowed in recycling and waste centres


The main hazard with Abestos is dust
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Old 3rd Sep 2004, 8:24 pm   #4
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Default Re: Asbestos in DAC90

Small quantities like this are not usually considered a health hazard unless handled carelessly. You should not do anything to produce dust, ie drill, cut or file. There are literally thousands of tonnes still in use in all sorts of places and removal is only necessary if something would give rise to dust.
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Old 3rd Sep 2004, 9:08 pm   #5
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Default Re: Asbestos in DAC90

In his book "Electronic Classics", Andy Emmerson recommends spraying (or brushing) asbestos generously with clear varnish. This has the efect of holding it together, and thus minimising the risk.

Of course it reduces its heat insulating properties, so it's perhaps not a good idea in the DAC90 where (if I remember correctly) the dropper is a snug fit in the asbestos lined housing.

In the DAC90 I would suggest the best approach would be to leave it alone. If you don't disturb it, it should be fine.

If you need to disturb it, spraying it with water should help keep reduce the dust. Maybe you can put the whole section in a bowel of water and work on it in the water?
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Old 5th Sep 2004, 11:09 am   #6
ekco1953
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Default Re: Asbestos in DAC90

Well, I bit the bullet .

Why I was concerned was that the asbestos was " fibrous " at the edges and the top part was sort of delaminating. To get the set going it was essential to replace a piece of paxolin and refit the connection at the top of the dropper.

I read Paul's post re varnish, which I don't think would stand the heat, however it got me thinking and I applied super glue all around the outside edge and at the delaminating part which I pressed back in place with a screwdriver. Not sure about the heat issue with super glue, but we'll see :. After that it just looked so much safer , and I went about the repair without too much concern.

I tend to agree with Bill about the small quantities and after some more web searching on white asbestos, I decided to go ahead. This was my PERSONAL solution and in no way do I recommend it as the way to go in general.

Sam, I can't really offer advice but since the case of the Pye is plastic I'd try Paul's suggestion of immersion in water (after removing the innards, of course : . This just might release the adhesion and allow safe removal.

I'm still interested to hear comments from others on the general subject. I'm off now to think about how to replace the top corner of the DAC90 back .

Thanks for replies.
Jim
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Old 5th Sep 2004, 3:23 pm   #7
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Default Re: Asbestos in DAC90

Quote:
Small quantities like this are not usually considered a health hazard unless handled carelessl
I have to agree, the name "asbestos" strikes fear into folk’s hearts these days, but I think it’s all about risk assessment. I have to confess that I have never been unduly worried about bits of asbestos in wireless sets. However, I was much more worried about old car brake linings because of the quantity of dust often found inside the assemblies. I was once in a workshop where a "numb skull" mechanic used an airline to "clean up" brake dust - I made an **extremely** quick exit! I believe these days’ brake linings no longer contain asbestos.

Don't for goodness quote me as an " expert " on this stuff, but my understanding is that different types of asbestos present vastly different risks. The worst types were ones used for insulating pipes and boiler installations. Often this was the so-called " blue” or Crocidolite asbestos, actually I think it is the form the stuff is presented in rather than the actual class of mineral that counts as far as risk is concerned. It's dangerous because of the fact that it is fibrous, and easily inhaled. I never seen any (thank god!) but I understand it has the consistency of the fibreglass-insulating material used in lofts today.

By contrast, asbestos cement is a mixture of Portland cement and a small quantity of asbestos, this is much less dangerous as the asbestos fibres are " bonded " by the cement, the material is hard. The stuff is still widely used as roofing (I don't know if it’s still actually being manufactured – probably not!). Somewhere in between (risk wise) is asbestos board, a bit like the gypsum board used today.

I am guessing that the majority of asbestos you will find in old wireless and TV sets is of the Portland type. I suppose though once it ages though it may "break down" (as mentioned in the post above) and present a higher risk.

I am quite “sensitive” about this as my Grandfather was a builder in the 30s and used the worst kinds of asbestos without any form of protection. He died in the early 70s of lung cancer at a relatively early age!

Chris
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Old 6th Sep 2004, 11:45 am   #8
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Default Re: Asbestos in DAC90

As I understand it, blue asbestos is the most hazardous, followed by brown. The reason being is that under a microscope, the fibres of blue and to a lesser extent brown asbestos resemble tiny needles. It is these needles that get lodged in the aveoli of the lung, cause irritation, and after 20 or so years may lead to cancer. One million of these 'needles' will fit on a pin head. By contrast, white asbestos fibres (which is the type that we are more likely to encounter) resembles fluffy cotton wool. Whilst these are not sharp, they can still clog up the lungs and may eventually may lead to a condition similar to silicosis. Although not as hazardous, it is advisable to reduce ones intake of the dust through sensible precautions. At work all the time we come across fuse carriers and switches which contain asbestos, it is difficult to avoid as there is so much of it about.
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Old 6th Sep 2004, 5:46 pm   #9
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Default Re: Asbestos in DAC90

FWIW I removed the asbestos in my DAC90. I followed the instructions detailed already - spray with water to damp down the dust, work outdoors, wear old clothing, double wrap in plastic bags, etc.

I removed the asbestos and the metal partition around the dropper and replaced the resistive dropper with a capacitive dropper detailed on Pauls website - http://www.vintage-radio.com/repair-...er-calcs.shtml . Taking this approach removes the need for the heatshield and the radio runs a lot cooler.
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Old 9th Sep 2004, 2:24 pm   #10
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Default Re: Asbestos in DAC90

A distant relative of mine used to live in a bungalow made of asbestos sheeting. This was quite a common building material in the 1920s. When it was demolished about 15 years ago, the demolition men smashed it up with sledghammers and dumped it in a big skip. I remember feeling at the time that this wasn't exactly best practice when handling asbestos, even white asbestos. It certainly puts the anguish over DAC90 heatshields into perspective though.

Best regards, Paul
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Old 11th Sep 2004, 1:33 pm   #11
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Default Re: Asbestos in DAC90

A good material to stabilize crumbling asbestos might be epoxy resin (the stuff used with fibreglass matting). This will tolerate heat well - eventually it will soften, but will harden again as it cools down. It doesn't produce any nasty vapour when heated AFAIK. I've not actually used it in this application though.

HTH, Paul
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Old 16th Sep 2004, 11:50 pm   #12
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Default Re: Asbestos in DAC90

I am no expert either but for what it's worth, I have tackled this problem by painting the asbestos with white emulsion. Using a model paint brush allows one to get into all the nooks and crannies and the heat doesn't seem to effect the paint and/or cause a smell. What it do quite effectively is to bond the asbestos into a solid mass hopefully preventing powdering and thereby rendering it safe.
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