Waterproof textile performance testing --- Hydrostatic Head Tester Test Method
Main
content:
1.
Preparation of performance factors waterproof and breathable fabric, principles
and influence;
2. Domestic
and international water-repellent fabric performance testing standards;
3. Hydrostatic testing methods;
4.
Hydrostatic testing method ---- Hydrostatic Head
Tester
The so-called water-resistant outer fabric means that water will
not penetrate the fabric, and it will not be dipped the inside, also known as
surface moisture resistance. Waterproof and breathable textile is a new
high-grade fabrics more important category, the rapid development in recent
years, the most popular. For example: Gore-Tex (GORE-TEX) fabrics, from the
United States WLGore & Associates, Inc. (Gore) invented and produced an exclusive,
thin, strong and durable film, it has a waterproof, breathable and
weather-resistant, which succeeded in break through the general fabric
breathable waterproof shortcomings, it is known as the "century of the
cloth"
GORE-TEX fabrics and Waterproofing Principle
I. A kind of fabric waterproof
Preparation for Fabric waterproof
General cotton, viscose, silk and linen and other more polyester, nylon,
polypropylene and other fiber absorbent, if the requirement that they have a
high level of water resistance to water for a variety of appliances, it must be
waterproof or water repellent.
Waterproof explanation fact often including the
"water-repellent" meaning. According to different properties of the
fabric surface finishing, it can be distinguished, can basically be divided
into two categories: one is waterproof but airtight finishing. It is a uniform
coating on the fabric surface layer of impermeable, water-insoluble coating,
finishing the fabric pore blockage, preventing water and air through the
fabric, which is also known as finishing coating finish (waterproof finishing).
Such as polyurethane resin, polypropylene alcohol resins, rubber, tung oil and
other treatment, the fabrics is not only impermeable and airtight, and feel too
hard, it is not suitable for articles of clothing, generally applicable to
industrial fabrics or outdoor. The other is waterproof and breathable
finishing, also known as water repellent finish. This refers to textile
finishing, finishing agents change the surface properties of the fibers,
hydrophilic fibers into a hydrophobic surface, the fabric is not easy to be
wetted, but still breathable, soft, commonly used in the production of
clothing, raincoats and other fabric.
Waterproof, water repellent principle
FIG γL and γS represent the surface tension of liquids and solids, γLS
represents the interfacial tension between the solid solution 2, θ is called
the touch angle. When θ> 90 °, the liquid does not wet the solid surface;
when θ <90 °, the liquid portion of the wet solid surfaces. Water repellent
finishing requirements θ angle the bigger the better. Various fiber materials
for water contact angle data vary widely, generally the order of: viscose
<acrylic cotton ≈ <nylon <wool <polyester <polypropylene. Viscose
good wet ability, polyester poor wet ability.
Affecting Factors of Fabric waterproof properties
There are many factors affected textiles of Waterproof performance, such
as the material itself and textile craft production processes and technical
issues, which will have implications, High or low Fabric waterproof performance
index is decided by the following factors aspects
The thickness of the fabric: The thicker the fabric, the greater the
dampness, the greater the water pressure resistance values.
Yarn thickness: For good absorbent fibers woven into the
fabric tightly, since the presence of the capillary effect, reducing the radius
of the yarn. Can improve fabric resistance to water
Tightness of the fabric: The distance between the yarn increases will
directly affect the level of water pressure resistance. Usually the fabric
structure more closely, the better the performance of its water impermeability
Coating membrane pore size: Membrane pore size the
greater the hydrostatic pressure, the worse the performance of coated fabrics
The size of the contact angle θ: When θ> 90. the fabric has water repellent
properties, with the increase of θ, the water pressure resistance values
corresponding increase in fabric
Coating thickness: The coating is too thin, hard surface
coating agent in a continuous deposition, reduced ability to withstand water
pressure coated fabrics; pressure-resistant thick coating capability, improved
fabric
Weft yarn performance is good or bad: Action by the water
pressure, good flexibility and easy weft yarn elongation, resulting in the
formation of a gap adjacent warp and weft, which drops easily seep through,
making the fabric water pressure resistance values decrease
Coating quality: Require that the entire cloth uniform,
with a certain fastness. With better the quality of coating, the better performance
of water permeability.
First,
the water resistance test standard
Presently,
domestic and international standards for fabric waterproof properties are the
following:
China National Standard
GB/T 4745-1997《Textile
fabrics-Determination of resistance to surface wetting-Spray test》
GB/T
4744-1997《Textile
fabrics-Determination of resistance to water penetration-Hydrostatic pressure
test》
GB/T
14577-1997《Determination
of water repellency of textile Bundesmann rain Act》
China Industry Standards
FZ/T01004-1991《Test Method for coated fabrics
resistance to water penetration (Hydrostatic Testing)》
International standard
ISO
4920:1981《Textile
fabrics - Determination of resistance to surface wetting spray test》
ISO
811:1981《Textile
fabrics-Determination of resistance to water penetration-Hydrostatic pressure
test》
ISO
1420:1987《Rubber and
plastic coated fabrics - Determination of resistance to water hydrostatic
pressure test》
Japanese standard：
JIS
L-1092《Textiles
hydrostatic water resistance test A》
American Association of Textile Chemists and Colorists
standard
AATCC21-83《Water repellency -water repellency
test method》
AATCC76-83《Water repellency -Dynamic water absorption test method》
AATCC-22:1996《Textile fabrics waterproof test:
spray test》
AATCC22-2001 《Water Repellency: Spray Test》
AATCC35-2000《Water Resistance: Rain Test》
AATCC42-2000《Water Resistance: Impact Penetration Test》
AATCC127-2003《Water Resistance: Hydrostatic
Pressure Test》
American Standard
ASTM
D751-95《Coated fabrics-
water resistance Test》
ASTM
D3393《Standard
Specification for Coated Fabrics—Waterproofness》
German standards
DIN
53888 《Determination
of water repellency of fabrics Bundesmann rain Act》
EN 20811-1992 《Textile fibers
- Determination of water penetration Hydrostatic pressure test》
EN
24920-1992 《Textiles -
Determination of wetting the fabric surface resistance (spray test)》
Hydrostatic Head Tester Test Method
1
2
3
Fabric
waterproof testing, it is divided into 3 kinds such as field testing,
simulations and laboratory testing.
Less cost on laboratory testing,
time is short; the results can be obtained relatively, more practical. The main
methods include hydrostatic test, spray test and water
absorption experiments. Wherein the hydrostatic pressure indicator is
one of the most important indicators of fabric waterproof, make the following
detailed description as below,
Hydrostatic
Head Tester
Test principle: dynamic testing, static testing and
custom procedural law test for detecting water-repellent properties of textiles
under a certain pressure. The sample is fixed on the standard test area by air
compressor will 0-5bar distilled water added to a full tank, the tank directly
connected to the test head, a certain amount of pressure delivered to the
sample. When the pressure curve shown in real time on the operator screen,
built-in a variety of testing standards, in order to convenience for user-friendly.
Hydrostatic
Head Tester Technical Parameters:
1. Testing pressure: 0-5000mbar (5000cmW.G);
2. Testing precision: Resolution with 0.1mbar;
3.Testing area: 100cm（10cm,19.63cm,26cm,28cm optional）;
4. Rising rate of pressure: choose according to the
standard also can input the specified value;
5. Testing units for option: mbar/kPa/Pa/cm w.c /mm
w.c;
6. Maximum thickness of sample: 40mm;
7. Compressed air: 6-8 bar (clean and dry air);
8. Alarming time: 0- 9,999 min (also can be set up
according to pressure or time);
9. Pneumatic clamps.
Product Information of Hydrostatic
Head Tester:
1. Multi-point touch operating system with
capacitive color touch screen of 7-inch, easy for controlling. Test results can
be saved to Excel file, and sent via WIFI to anywhere, can also be saved to the
SD card.
2. Simple and convenient test fixture is designed
to provide superior gripping force, ensuring that the water does not leak out
from the side edge even in high pressure.
3. Automatic water supply, could provide a
self-adding to test the specified position by means of built-in water level
sensor,;
4. High-precision pressure sensors and pressure
control system, with high precision and broad test range;
5. Multiple pressure units for selection
(mbar/kPa/Pa/cm w.c/mm w.c), meet different requirements and the actual need;
6.Selectable rate of pressure according to the
standard data, or by user custom (if the pressure is beyond the maximum limit
of 5000 mbar, the system will remind with pressure exceeding to ensure the
safety in operation);
7. Pressure alarm or time alarm could be set to
save the observation time for operators, audible alarm when reaching the alarm
conditions;
8. In addition to the internal standard, the user
can also choose the custom mode to set parameters for testing;
9. LED soft illumination system, digitally adjust
the lighting brightness;
10. Test software configured with a variety of test
standard, user-friendly;
11.With powerful PC software for optional, and the
function of test video playback,synchronized in the test data, pressure curve,
and video, accurately detecting the water drops to measure pressure of the
cloth, completely making an elimination of the observation error on human eyes.
Hydrostatic Head Tester Testing
Standards:
GB/T 4744, AATCC 127, ERT 120-1/160-0, BS EN 20811/3321/3424, AFNOR
G07-057, ISO 811, JIS L1092A, JIS L1092.B-a, JIS L1092 B-b, ASTM F903C, ASTM
F1670, ASTM F1671, EN 1734, ISO 1420, FZ/T 01004
Hydrostatic Head Tester Applications:
Hydrostatic Head Tester is designed to determine the
waterproof property of outdoor wears, umbrella, and waterproof fabric. It is
also used to test the resistance of permeability of synthetic blood for
materials used in protective clothing. Dynamic, static, custom mode for
different test requirements. One side of the specimen is subjected to a
hydrostatic pressure that increasing at a constant rate, then will be ended
until three points of leakage appear on its other side. The instrument contains
a high precision pressure control system, which could produce the test pressure
in an internal water tank. Real-time pressure curve displays on the screen.
Hydrostatic Head Tester Basic configuration:
1. Hydrostatic Head Tester;
2. 100 cm 2 Test Head;
3. Analysis software;
4. A set of PC test software (optional).
