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Tyco Electronics Corporation
300 Constitutional Drive
Menlo Park, CA 94025 USA
Specification
This Issue:
Date:
Replaces:
RT-220
Issue 3
July 20, 1997
Issue 2
THERMOFIT® RT-220 TUBING
Flexible, Heat-Shrinkable,
Flame-Retarded Modified Fluoropolymer - Low Outgassing
1. SCOPE
This specification covers the requirements for flexible electrical insulating, extruded tubing whose diameter
will reduce to a predetermined size upon the application of heat in excess of 150°C (302°F).
Tubing shall be flame retarded and shall be black or white.
2. APPLICABLE DOCUMENTS
This specification takes precedence over documents referenced herein. Unless otherwise specified, the latest
issue of reference documents applies. The following documents form a part of this specification to the extent
specified herein.
2.1 GOVERNMENT-FURNISHED DOCUMENTS
Military
MIL-G-5572 Gasoline, Aviation, Grades 80/87, 100/130, and 115/145
MIL-H-5606 Hydraulic Fluid, Petroleum Base, Aircraft, Missile and Ordnance
MIL-T-5624 Turbine Fuel, Aviation, Grades JP-4 and JP-5
MIL-L-23699 Lubricating Oil, Aircraft Turbine Engine, Synthetic Base
MIL-STD-104 Limits for Electrical Insulation Color
2.2 OTHER PUBLICATIONS
American Society for Testing and Materials (ASTM)
D 2671 Standard Methods of Testing Heat-Shrinkable Tubing for Electrical Use
D 3032 Method of Testing Hookup Wire Insulation
E 595 Test Method for Total Mass Loss and Collected Volatile Condensable Materials from
Outgassing in a Vacuum Environment
G 21 Standard Recommended Practice for Determining Resistance of Synthetic Polymeric
Materials to Fungi
(Copies of ASTM publications may be obtained from the American Society for Testing and Materials, 1916
Race Street, Philadelphia, Pennsylvania 19103.)
Underwriters Laboratories
UL 224 Standard for Extruded Insulating Tubing
(Copies of UL publications may be obtained from Underwriters Laboratories Inc., 1285 Walt Whitman Road,
Melville, Long Island, New York 11746.)
Page 2 SPECIFICATION RT-220 ISSUE 3
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3. REQUIREMENTS
3.1 MATERIALS
The tubing shall be fabricated from thermally stabilized, modified fluoropolymer and shall be crosslinked by
irradiation. It shall be homogeneous and essentially free from flaws, defects, pinholes, bubbles, seams,
cracks, and inclusions.
3.2 PROPERTIES
The tubing shall meet the requirements of Table 3.
4. QUALITY ASSURANCE PROVISIONS
4.1 CLASSIFICATION OF TESTS
4.1.1 Qualification Tests
Qualification tests are those performed on tubing submitted for qualification as a satisfactory product and
shall consist of all tests listed in this specification.
4.1.2 Acceptance Tests
Acceptance tests are those performed on tubing submitted for acceptance under contract. Acceptance tests
shall consist of the following: dimensions, concentricity, longitudinal change, recovery angle, tensile
strength, ultimate elongation, secant modulus, flammability, and heat shock.
4.2 SAMPLING INSTRUCTIONS
4.2.1 Qualification Test Samples
Qualification test samples shall consist of 50 feet (15 m) of tubing. Qualification of any size within each size
range specified below shall qualify all sizes within that size range.
Range of Sizes
3/64 through 1/4
3/8 through 1
For Dynamic Cut-Through test, size 3/16 shall qualify all sizes. For Fungus Resistance test, any size shall
qualify all sizes.
4.2.2 Acceptance Test Samples
Acceptance test samples shall consist of not less than 16 feet (5 m) of tubing selected at random from each
lot. A lot shall consist of all tubing of the same size from the same production run and offered for inspection
at the same time.
SPECIFICATION RT-220 ISSUE 3 Page 3
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4.3 TEST PROCEDURES
Unless otherwise specified, tests shall be performed on specimens which have been fully recovered by
conditioning for 3 minutes in a 200 ± 5°C (392 ± 9°F) oven. Prior to all testing, the test specimens (and
measurement gauges, when applicable) shall be conditioned for 3 hours at 23 ± 3°C (73 ± 5°F) and 50 ± 5
percent relative humidity. All ovens shall be of the mechanical convection type in which air passes the
specimens at a velocity of 100 to 200 feet (30 to 60 m) per minute.
4.3.1 Dimensions and Longitudinal Change
Three 6-inch (150-mm) specimens of tubing, as supplied, shall be measured for length
± 1/32 inch (± 1 mm), and inside diameter in accordance with ASTM D 2671, conditioned for
3 minutes in a 200 ± 5°C (392 ± 9°F) oven, cooled to 23 ± 3°C (73 ± 5°F) and then remeasured. Prior to and
after conditioning, the dimensions of the tubing shall be in accordance with
Table 1 and the longitudinal change shall be in accordance with Table 3. The longitudinal change shall be
calculated as follows:
C = L1 - L0
L0 x 100
Where: C = Longitudinal Change [Percent]
L
0 = Length Before Conditioning
L
1 = Length After Conditioning
4.3.2 Concentricity as Supplied
Three 6-inch (150-mm) specimens of tubing, as supplied, shall be measured for minimum and maximum wall
thickness. Concentricity shall be calculated as follows:
C = Wmin
Wmax x 100
Where: C = Concentricity [Percent]
W
min = Minimum Wall Thickness
W
max = Maximum Wall Thickness
4.3.3 Weight Per Length
A 12 ± 1/32 inch (305 ± 0.8 mm) length of tubing, as supplied, shall be weighed. The weight shall be
multiplied by 100 and reported as pounds/100 ft (kg/100 m).
4.3.4 Recovery Angle
A length of tubing shall be cut such that the end of the tubing is 90 degrees to the longitudinal axis. The
tubing shall be recovered in accordance with Section 4.3, and by means of an optical comparitor or
equivalent, the angle between the end and the longitudinal axis shall be measured. The deviation from 90
degrees shall be reported as the recovery angle.
4.3.5 Tensile Strength and Ultimate Elongation
The tensile strength and ultimate elongation of the tubing shall be determined in accordance with ASTM D
2671 using 1-inch (25-mm) bench marks and a 1-inch (25-mm) initial jaw separation. The speed of jaw
separation shall be 20 ± 2 inches (500 ± 50 mm) per minute.
Page 4 SPECIFICATION RT-220 ISSUE 3
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4.3.6 Low Temperature Flexibility
For tubing of expanded diameter 1/4 inch (6 mm) or greater, three strip specimens, 1/4 inch
(6 mm) wide and 12 inches (300 mm) long, shall be cut from the expanded tubing. For tubing of expanded
diameter less than 1/4 inch (6 mm) three tubular specimens, 12 inches (300 mm) long, shall be cut from the
expanded tubing. The specimens shall be recovered in accordance with Section 4.3 and conditioned with
appropriate mandrels for 4 hours at -55 ± 2°C (-67 ± 4°F). The mandrel diameter shall be 10 times the
specimen thickness, ± 10 percent. For tubular specimens, the specimen thickness shall be equivalent to the
outside diameter. While at the specified temperature, and without removing the specimens from the cold
chamber, the specimens shall be wrapped 360 degrees around the mandrel in approximately 2 seconds. Any
side cracking, caused by flattening of the specimens on the mandrel, shall be disregarded.
4.3.7 Heat Shock
Three 6-inch (150-mm) specimens of tubing shall be conditioned for 4 hours in a 250 ± 5°C
(482 ± 9°F) oven. The specimens shall be removed from the oven, cooled to 23 ± 3°C (73 ± 5°F), wrapped
180 degrees around a mandrel selected in accordance with Table 2, and then visually examined for evidence
of dripping, flowing, or cracking. Any side cracking caused by flattening of the specimen on the mandrel
shall not constitute failure.
4.3.8 Dynamic Cut-Through at Temperature
Two 6-inch (150-mm) lengths of size 3/16-inch tubing shall each be recovered on a 7-inch
(175-mm) length of 3/32-inch (2.38-mm) oil hardened drill rod, by placing in a 200 ± 5°C
(392 ± 9°F) mechanical convection oven for 3 minutes. The cut-through tests shall be performed at 135 ±
3°C (275 ± 5°F) in accordance with ASTM D 3032 using the optional cutting edge. Four readings shall be
taken on each of the assemblies.
4.3.9 Heat Resistance
Specimens in accordance with Section 4.3.5 shall be conditioned for 336 hours in a 225 ± 3°C
(437 ± 5°F) oven. The specimens shall be removed from the oven, cooled to 23 ± 3°C (73 ± 5°F) and tested
for elongation in accordance with Section 4.3.5.
4.3.10 Copper Stability
Three 6-inch (150-mm) specimens of tubing shall be slid over a snug-fitting, straight, clean, bare copper
conductor. For tubing sizes 1/4 and smaller, a solid conductor shall be used; for tubing sizes 3/8 and larger, a
solid or tubular conductor shall be used. The specimens on the conductors shall be conditioned for 24 hours
in a desiccator or similar humidity chamber at 90 to 95 percent relative humidity and 23 ± 3°C (73 ± 5°F).
The specimens on the conductors then shall be conditioned for 168 hours in a 180 ± 3°C (356 ± 5°F) oven.
After conditioning, the specimens shall be removed from the oven and cooled to 23 ± 3°C (73 ± 5°F). The
copper conductor then shall be removed from the tubing, and the tubing and conductor shall be examined.
Darkening of the copper due to normal air oxidation shall not be cause for rejection. The tubing shall be
tested for elongation in accordance with 4.3.5.
SPECIFICATION RT-220 ISSUE 3 Page 5
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4.3.11 Corrosive Effect
4.3.11.1 Copper Mirror Corrosion
The tubing shall be tested for copper mirror corrosion in accordance with ASTM D 2671, Procedure A, for
16 hours at 160 ± 3°C (320 ± 5°F). For tubing sizes 1/8 and larger, specimens shall consist of 1/4 x 1 inch (6
x 25 mm) strips cut longitudinally. Evidence of corrosion shall be the removal of copper from a mirror,
leaving an area of transparency greater than 5 percent of its total area.
4.3.11.2 Corrosion in Contact with Copper
The tubing shall be tested for corrosion in contact with copper for 16 hours at 175 ± 3°C (347 ± 5°F) in
accordance with ASTM D 2671, Procedure B.
4.3.12 Fluid Resistance
Six 6-inch (150-mm) specimens of tubing, prepared and measured in accordance with ASTM D 2671 solvent
resistance, shall be completely immersed in each listed fluid for 24 ± 2 hours at 50 ± 3°C (122 ± 5°F). The
volume of the fluid shall be not less than 20 times that of the specimens. After immersion, the specimens
shall be lightly wiped and air-dried for 30 to 60 minutes at room temperature. Three specimens then shall be
tested for dielectric strength and the other three for tensile strength.
4.3.13 Vacuum Outgassing
Three 0.5 ± .05 gram specimens shall be recovered for 3 minutes at 200°C and then tested for percent total
weight loss and percent volatile condensable materials. The conditions for testing are: exposure time, 24
hours; sample temperature 125 ± 3°C; condensing surface temperature,
18 ± 3°C; and pressure, not greater than 1 x 10-5 torr. The vacuum shall be provided by a diffusion pump,
liquid nitrogen trap vacuum system. The apparatus shall consist of a glass sample chamber, refluxing liquid
heat source and a polished stainless steel plate in close contact with a copper cold finger cooled internally by
circulating water. The axis of the exit of the sample chamber shall be perpendicular to and approximately 15-
mm from the cooled condensing plate. A Cahn RG micro balance or equivalent shall be used for weighing.
The specimen shall be weighed before and after conditioning and total weight loss calculated and the
condensing plate shall be weighed before and after to calculate percent volatile condensable material.
4.4 REJECTION AND RETEST
Failure of any sample of tubing to conform to any one of the requirements of this specification shall be cause
for rejection of the lot represented. Tubing which has been rejected may be replaced or reworked to correct
the defects and resubmitted for acceptance. Before resubmitting, full particulars concerning previous
rejection and action taken to correct the defects shall be furnished to the inspector.
5. PREPARATION FOR DELIVERY
5.1 FORM
The tubing shall be supplied on spools, unless otherwise specified.
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5.2 PACKAGING
Packaging shall be in accordance with good commercial practice. The shipping container shall not be less
than 125-pound-test fiberboard.
5.3 MARKING
Each container of tubing shall be permanently and legibly marked with the size, quantity, manufacturer's
identification, specification number, color, lot number and date of manufacturing.
SPECIFICATION RT-220 ISSUE 3 Page 7
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TABLE 1
Inside Diameters and Wall Thicknesses of Tubing
Expanded
As Supplied
Recovered Dimension -- After Heating
Weight,
As Supplied,
Size Inside Dia. Inside Dia. Wall Thickness Maximum
Minimum Maximum Minimum Maximum Nominal lbs/
kg/
in.
mm. in. mm. in. mm. in. mm. in. mm. 100 ft 100 m
3/64 0.046 1.17 0.023 0.58 0.007 0.18 0.012 0.30 0.009 0.23 0.10 0.15
1/16 0.063 1.60 0.031 0.79 0.007 0.18 0.012 0.30 0.009 0.23 0.13 0.19
3/32 0.093 2.36 0.046 1.17 0.007 0.18 0.012 0.30 0.009 0.23 0.17 0.25
1/8 0.125 3.18 0.062 1.60 0.007 0.18 0.012 0.30 0.009 0.23 0.22 0.33
3/16 0.187 4.75 0.093 2.36 0.007 0.18 0.012 0.30 0.009 0.23 0.31 0.46
1/4 0.250 6.35 0.125 3.18 0.008 0.20 0.015 0.38 0.011 0.28 0.40 0.60
3/8 0.375 9.53 0.187 4.75 0.008 0.20 0.015 0.38 0.011 0.28 0.73 1.09
1/2 0.500 12.70 0.250 6.35 0.008 0.20 0.015 0.38 0.011 0.28 0.96 1.43
3/4 0.750 19.05 0.375 9.53 0.013 0.33 0.020 0.51 0.016 0.41 1.92 2.85
1 1.000 25.40 0.500 12.70 0.015 0.38 0.022 0.56 0.018 0.46 2.78 4.14
TABLE 2
Mandrel Dimensions for Heat Shock
Tubing Mandrel Diameter
in. mm.
3/64 to 3/16 inclusive 5/16 7.9
1/4 to 1 inclusive 3/4 19.1
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TABLE 3
Requirements
PROPERTY UNIT REQUIREMENT TEST METHOD
PHYSICAL
Dimensions
Inches (mm)
In accordance with Table 1
Section 4.3.1
Longitudinal Change Percent +0, -10 ASTM D 2671
Concentricity as Supplied Percent 70% minimum Section 4.3.2
Weight Per Length as Supplied lbs/100 ft
(kg/100 m)
maximum
In accordance with Table 1 Section 4.3.3
Recovery Angle Degrees 5 maximum Section 4.3.4
Tensile Strength psi (MPa) 4000 minimum (27.6) Section 4.3.5
Ultimate Elongation Percent 300 minimum ASTM D 2671
Secant Modulus psi (MPa) 50,000 maximum (345) ASTM D 2671
Low Temperature Flexibility
4 hours at -55°C (-67°F)
--- No cracking Section 4.3.6
Heat Shock
4 hours at 250°C (482°F)
--- No dripping, flowing, or cracking Section 4.3.7
Dynamic Cut-Through
at 135°C (275°F)
lbs (kg) 5 minimum (2.3) Section 4.3.8
ASTM D 3032
Heat Resistance
336 hours at 225°C (437°F)
Followed by test for:
--- --- Section 4.3.9
Ultimate Elongation Percent 250 minimum Section 4.3.5
ASTM D 2671
Copper Stability
168 hours at 180°C (356°F)
Followed by test for
--- No brittleness, glazing or severe
discoloration of tubing. No
pitting or blackening of copper.
Section 4.3.10
Ultimate Elongation Percent 250 minimum Section 4.3.5
ASTM D 2671
Color --- MIL-STD-104, Class I MIL-STD-104
ELECTRICAL
Dielectric Strength
Volts/ mil
(volts /mm)
500 minimum (19,680)
ASTM D 2671
Volume Resistivity ohm-cm 1011 minimum ASTM D 2671
CHEMICAL
Corrosive Effect
---
Noncorrosive
Section 4.3.11
ASTM D 2671
Copper Mirror Corrosion
16 hours at 160°C (320°F)
--- Copper Removal
5%, maximum
Section 4.3.11.1
ASTM D 2671
Procedure A
Copper Contact Corrosion
16 hours at 175°C (347°F)
--- No blackening or pitting of
copper
Section 4.3.11.2
ASTM D 2671
Procedure B
Flammability --- 1) 25% maximum flag burn
2) no burning of cotton
3) no flaming, or glowing longer
than 60 seconds
UL 224, VW-1
ASTM D 2671
Procedure C
SPECIFICATION RT-220 ISSUE 3 Page 9
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TABLE 3
Requirements
(continued)
PROPERTY UNIT REQUIREMENT TEST METHOD
CHEMICAL (continued)
Fungus Resistance
---
Rating of 1 or less
ASTM G 21
Water Absorption
24 hours at 23°C (73°F)
Percent 0.5 maximum ASTM D 2671
Fluid Resistance
24 hours at 50°C (122°F)
JP-4 Fuel (MIL-T-5624)
Hydraulic Fluid (MIL-H-5606)
Aviation Gasoline (100/130)
(MIL-G-5572)
Water
Trichloroethane
Lubricating Oil MIL-L-23699
Followed by tests for:
--- --- Section 4.3.12
ASTM D 2671
Dielectric Strength Volts/mil
(volts /mm)
400 minimum (15,760) ASTM D 2671
Tensile Strength psi (MPa) 2000 minimum (13.8) Section 4.3.5
ASTM D 2671
Vacuum Outgassing
TML (Total Mass Loss)
Percent 1.0 maximum Section 4.3.13
VCM (Volatile Condensable
Materials)
Percent 0.1 maximum ASTM E 595
