Document 93Yjo9BxyGg2q7nxnr8nEDqJ5
HX3CBEST0S VERB & CABI CO. Division of Cerro de Pasco Corporation
IKTESHAL MaSBMKEJM
Other addressees for information
R.?. Coyle (S) G.3. Biettacr File (S)
To: J.F.S. Abbott
-
From: D.A. Charlotte
Subject: small Diameter Type SA Wire
Hew Haven, Conn. January 11, i960
W.E. Tierney recently reoiested that ve consider a small diameter silicone
rubber asbestos braided wire with which ve might possibly get Underwriters9 approval* Reduction in diameter would be accomplished by the use cf & finer
asbestos braiding yazn to be applied over the standard wall of silicone rubber required for Type SA*
Cur present 9-Cut asbestos yam gives a .C^O" wall (.050" adder). The i3-Cut
asbestos yazn that we use on small sizes of Teble ML Mining Cable gives a
.0275" wall (.055" adder). We have used some 30-Cut yazn, .0225" wall (.04?"
adder), cut have run into considerable breakage in production due to low
tmsile strength. In order to meet the 60$ Tflinirryjn asbestos content on very
fine yams, finer carrier threads must be used end this accounts for the low
tensile strength. We have had fair success when running 2 ends of the 33-cut
yazn.
................
Other sizes of yam are available, namely 20, 24, 28-cut, with tensile strengths of 2, 1 3/4, 1 1/2 lbs. respectively. Cur l8-eut yazn has a 2 lb. tensile, and the 30-cut yam a 1 l/4 lb. tensile. It is possible that ve could braid success fully with one of the intermediate sizes but this would hove to be investigated by R. & D. In any such investigation, braid adders should be carefully checked end this applies also to the 30-cut yarn as ve hove very little factual data to substantiate the adder of .045" now shown an specification cards.
A table of comparative diameters is shown below to indicate approximate overall diameters with 9-cut (regular Type SA), 18-cut and 30-cut yam on a solid conductor. Diameter of Type R is shown in last column.
RBB00713
Continued
2- January 11, 0960
size AW
9-Cut yarn
Outside Diameter
18-Cut yarn
30-Cut yam
Type ;
14 *243
.218
12 260
235
10
.231 '
.256
8
*350 *
.315-
.208
.225 fitf 305
* .045" braid thickness (*090" adder) es core diameter is .260".
*171 .188 *242
.311
The above tabulation indicates that ve can approach Type R diameters on sizes
#10 and 6 AW* However, an sizes #14 and 12 AW ve are faced with 3/64" insulation on Type SA whereas Type R has 2/64" insulation* If ve decide to
contact the Underwriters relative to decrease in asbestos braid thickness, ve should consider inquiring into the possibility of 2/64" silicone rubber on sizes #14 and #12 AW*
zm
D.A. Charlotte
RBB 00714