EuroWire November 2017

Technical article

PHRR (Kw/m 2 )

T ig (Seconds)

[2] T Richard Hull, Krzysztof Lebek, Maddalena Pezzani and Silvio Messa. “Comparison of toxic product yields of burning cables in bench and large scale experiments”, Fire Safety Journal, 43 (2), pp 140-150, 2008. ISSN 0379-7112

Sample

Brominated XHHW-2 FT2

1,104

69

Brominated XHHW-2 VWI

385

84

Experimental zero halogen

449

78

PHHR – Peak Heat Release Rate T ig – Time to ignition

▲ ▲ Table 2 : Summary of cone calorimeter for the final zero halogen formulation against commercial brominated XHHW-2 systems. 40kW/m 2 heat flux 3mm samples

2.4 HF approval The final compound has been tested at UL and certified as being halogen free, and certified cables are now eligible to bear the optional “HF” suffix in the cable surface print following the product name. The testing for the optional marking is based on the requirements of IEC 62831 and UL2885 standards covering determination of halogen acid gas, pH, conductivity and chemical assessment of halogens. 3 Further work The compound described here was designed to meet the FT2 horizontal flame test with the full understanding that it will be useful in multi-conductor cabled products needing to meet a variety of full-scale fire test scenarios. Work is ongoing to map out the fire and low smoke performance of this formulation concept on full-scale fire tests including FT-4, ST-1 and VW-1 in circuit sizes. The cone calorimeter was used in this research project as a screening tool and work is ongoing to understand how to fully exploit this tool in future developments. 4 Conclusions A robust moisture curable primary insulation has been developed that is fully capable of meeting the stringent requirements of UL44. n 5 Acknowledegments Special thanks to the management and executive of SACO AEI Polymers for support in this work.

While low-compression ‘straight’ screws are recommended for heavily filled LSZH systems, industrial scale production indicates the chosen compound also has the flexibility for production on some typical PVC/PE screws with higher (3:1) compression ratios. Shelf life is a particular concern for moisture curable compounds in an industrial setting. Work is ongoing to assess shelf life performance, but results indicate performance well in excess of six months. 2.3 Final performance The final compound has been approved for types SIS, XHH, XHHW, XHHW-2, RHH, RHW, RHW-2 rated 600V in all colours and suitable for the optional -40ºC and Oil Res I and II requirements along with Gasoline and Oil Resistance II. Typical properties from cable core samples are shown in Table 3 . ▼ ▼ Table 3 : Summary of typical properties on wire

Property

Tensile strength/psi

2,200

Elongation %

400

Crush resistance

>1,400

High temp deformation % (131ºC)

<15

Cold blend ºC

-40

SACO AEI Polymers Sandwich Industrial Estate Sandwich, UK

Cold impact ºC

-40

Oil Resistance I&II

Pass

SACO AEI Polymers 3220 Crocker Avenue Sheboygan Wisconsin, USA Tel : +1 920 694 3670 Email : david.roberts@sacoaei.com Website : www.sacoaei.com

Gasoline and Oil Resistance II Long term wet IR 90ºCmin requirement MΩ/1,000 feet

Pass

6 References

180

[1] Robinson, J E, Samson, F, and Sultan, B-Å, “Cable Fire Smoke and Toxicity”, Eurocable 2000, Stuttgart, Germany, 2000

51

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November 2017