In a past life I used to be involved in the flame retardant and PVC industry and
ran a plastics flammability lab.

Lead soaps (stearates etc.) are used as stabilizers for PVC so that they
withstand processing and operating temperatures (PVC starts to decompose - char
not burn - above 140C).  There are substitutes which are used widely but as I
recall lead soaps are particularly effective for wire and other non-chewable
applications.

Metallic lead coatings were used widely in coating splices in buried high
voltage power lines and are still used but I believe are being replaced by
alternate technologies?

The normal flame retardant system in flexible PVC is based on antimony oxide,
which from memory reacts with the chlorine in the PVC to form a free radical
trap that stops flame propagation.  Alternatives include phosphate and other low
flammability plasticizers.


_________________
Alan Rae
Director of Technology
Cookson Electronics Inc.
225 Foxborough Blvd. Suite 150
Foxborough MA 02035
USA
[log in to unmask]
Phone: (508) 541-5843
Fax: (508) 541-5877




Liz Harriman <[log in to unmask]> on 09/24/99 12:45:26 PM

To:   [log in to unmask]
cc:
Fax to:
Subject:  Re: [LF] Lead uses in cabling




Yes, there is a substantial amount of lead used in the PVC coating of
electrical and communication cables.  In 1997 in Massachusetts, almost half
a million pounds of lead were used in PVC coatings on wire cable.  As I
understand it, the purpose is to obtain a UL fire rating, at least for the
electrical wire.

In fiber optic, I believe the material is a leaded glass compound.  THere
is a Massachusetts company which wants to know if there are alternatives.

I would appreciate any additional insight to the use of lead in these
applications that others could add.

Liz Harriman

At 11:22 AM 9/24/1999 -0500, you wrote:
>Is there lead in PVC coated cabling, or Fiber Optic cables?  Please
enlighten me.
>
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Liz Harriman
Massachusetts Toxics Use Reduction Institute
University of Massachusetts Lowell
One University Ave
Lowell, MA  01854

Phone: 978-934-3387     Fax: 978-934-3050

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For technical support contact Gayatri Sardeshpande [log in to unmask] or 847-790-5365.
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