ANSI SCTE 251-2018 pdf free download – Test Procedure for Determining the Thermal Oxidative Stability of Foamed Polyethylene.
1.2. Scope
This method covers the determination of an Oxidative Induction Time(OIT) value for coaxial cable,foamed polyethylene, and insulation materials removed from completed cable products. This testprocedure is based on the ASTM D4565.The OrT value is determined by a thermo-analytical
measurement of the onset time for the exothermic oxidation of insulation in pure oxygen, at a specifiedtemperature.
1.3.Benefits
This document is designed to benefit manufacturers and end users of product tested to this procedure bysupplying a standardized method for determining an Oxidative Induction Time (OIT) value for coaxialcable, foamed polyethylene, and insulation materials removed from completed cable products.
1.4. Intended Audience
This document is intended for anyone desiring to make industry standard OrT measurements of coaxialcable, or for anyone acquiring product purported to have been tested using this method.
1.5. Areas for Further Investigation or to be Added in Future VersionsNone.
2. Normative References
The following documents contain provisions, which, through reference in this text, constitute provisionsof this document. At the time of Subcommittee approval, the editions indicated were valid. All documentsare subject to revision; and while parties to any agreement based on this document are encouraged to
investigate the possibility of applying the most recent editions of the documents listed below, they arereminded that newer editions of those documents might not be compatible with the referenced version.
2.1. SCTE References
.No normative references are applicable.
2.2. Standards from Other Organizations.
No normative references are applicable.
2.3. Published Materials
• No normative references are applicable.
3. Informative References
The following documents might provide valuable information to the reader but are not required when complying with this document.
3.1. SCTE References
• ANSI/SCTE 74 2011 Specification for Braided 75 Ohm Flexible RF Coaxial Drop Cables
3.2. Standards from Other Organizations
• ASTM D4565
3.3. Published Materials
• No informative references are applicable.
6. General
Two types of insulation test samples are described.Type ll sample description is presented forinformation only.Type I samples are to be used:
. Type I—Insulation removed from cable (no copper present)(Recommended method).
oUse Type I samples to measure the intrinsic stability of the material and the efficacy of
thermal stabilizers such as antioxidants.
. Type ll—Insulation on the wire (insulation and copper conductor).
oUse Type Il samples to evaluate not only the thermal stability, but also the metal
deactivation efficacy of the additives.
Significance and Use:
The OIT value measures the oxidative thermal stability of a material and is primarily dependent on:
the intrinsic thermal stability of the material,
the type and concentration of antioxidants and other thermal stabilizers present,.the type and concentration of metal deactivators present, and the test temperature.
Discussion—Other components in the foam material may cause secondary effects. The OrT value forinsulation may be significantly altered by contamination or additives such as pigments, fillers, andprocessing aids as well as catalyst residues from the cable,wire, insulation , or resin manufacture.TheorT value may increase or decrease depending on whether these additives and residues act as oxidationinhibitors or promoters at the test temperature.At typical test temperatures (for example,ANSISCTE74requires 180 C), compounds present in the polyolefin material may decompose and change the
polyolefin oxidation mechanism and thereby the OrT value. If the oxidation mechanism is so altered, thenthe OrT value may not correlate to aging at normal use temperatures. Before using the OrT value to
predict field performance and lifetimes,additional studies may be required to establish a correlation
between the OrT value measured at high temperature and the performance of the polyolefin under typicalfield conditions.
The OrT value is useful as a product performance test and quality control parameter, or a research anddevelopment tool for polyolefin materials.
7. Apparatus, Reagents and Materials
Calorimeter—This OIT Test is performed using commercial analyzers known as Differential ScanningCalorimeters (DSC) similar to the Perkin Elmer DSC8000 or equivalent which measures heat flow as afunction of time and temperature. A DSC with isothermal control and specimen temperature precision ofat least ±0.1°C is required. See Note 1.ANSI SCTE 251 pdf download.