The test results are composed of test data and units! There are sometimes many choices for this unit, and inconsistencies in the units used will inevitably lead to differences in the expression of detected values. Therefore, understanding the units used in testing projects can help us understand testing more accurately. Below I will briefly organize the common test items and the conversion relationship between units.
【Waterproof Test】
Surface water repellency:
Comparing the rating with the standard sample card, 5 levels are good, 1 level is poor, and it can be rated as an intermediate half level.
ISO, GB, JIS methods: Level 1, 2, 3, 4, 5
AATCC method: 50, 70, 80, 90, 100 points
【Hydrostatic Pressure】
Commonly used units: kilopascal (Kpa), centimeter of water column (cmH2O), millimeter of water column (mmH2O), millibar (mbar)
Conversion relationship:
1 kPa = 10 cmH2O = 100 mmH2O = 10 mbar
【Rain test】
The result is the increase in the weight of the absorbent paper behind the sample.
Commonly used units: grams (g)
【Oil repellency test】
Drop No. 1 to No. 8 oil onto the surface of the sample, judge whether it passes based on the shape of the drop, and determine the grade based on the number of oils that can pass through.
Commonly used units: level
【Easy stain removal test】
First, drop the test oil on the surface of the sample and apply a certain pressure for a specified time; then put the sample into a washing machine for washing and observe the removal of oil stains. Compare the rating with the standard rating sample, 5 levels are good and 1 level is poor.
Commonly used units: level
【Breathability Test】
The assessment is based on the flow rate of the sample passing through the air per unit time, or the amount of the sample passing through the air per unit time and unit area.
Commonly used units: cubic centimeter/second/square centimeter (cm3/s/cm2 or cm3/cm2.s)
Cubic feet/minute/square foot (ft3/min/ft2)
Derivation unit: millimeter/second (mm/s)
Conversion relationship:
1 cm3/ s / cm2= 10 mm/s
1 cm3/ s / cm2= 1.967 ft3/ min / ft2
【Water Absorption Test】
Water drop test:
Drop water droplets onto the surface of the sample until the mirror effect of the water droplets is eliminated. Assess the time required.
Commonly used units: seconds (S)
【 Wicking Effect 】
Place a sample of a certain width vertically in the water about 1.5cm, and see how many centimeters the water climbs up along the sample within the specified time.
Commonly used units: centimeter/time (cm/min)
【Moisture permeability test】
Assess the weight of moisture absorbed or evaporated by the sample per unit area and unit time.
Commonly used units: grams/square meter. 24 hours (g/m2.24h)
Conversion relationship: 1 g/m2.24h = 24 g/m2. h, 1 g/m2.24h =1 g/m2.d
【Thermal resistance Rct】
The sample is processed by dry heat flow through a defined area under conditions of stable temperature gradient.
Commonly used units: square meter Kelvin/watt (m2.K/W)
【Moisture resistance Ret】
The sample is processed by evaporating heat flow through a certain area under conditions of stable water vapor pressure gradient.
Commonly used units: square meter Pascal/watt (m2.Pa/W)
【Insulation rate】
When the temperature is 21°C and the air flow does not exceed 0.1M/S, when a sedentary person (whose metabolism is 58W/m2) feels comfortable, the insulation value of the clothing he wears is 1 clo value (clo)
Commonly used units: clo value (clo)
Conversion relationship: 1 clo = 6.451 Rct
【UV protection test】
Use single-color or multi-color UV rays (band 290~415nm) to irradiate the sample, collect the total spectral transmission rays, measure the total spectral transmittance, and calculate the sample’s ultraviolet protection factor UPF. When UPF > 50, and UVA 50 or 50+
Commonly used units: UPF
When UPF > 40, and UVA 40 or 40+
When UPF > 50, and UVA 50 or 50+
【Anti-static test】
Half-life method:
Within the specified time, high-voltage current is connected to the sample, and the time required from the moment the voltage is turned off to when the voltage decays to 1/2 (i.e., the half-life) is recorded.
Commonly used units: seconds (S)
Charge surface density method:
Rub the surface of the sample a certain number of times to measure the charge per unit area of the sample.
Commonly used units: uC/ m2
Voltage method:
Under certain tension conditions, the sample is rubbed against a standard cloth, and the charging status of the sample is evaluated based on the high voltage generated within a specified period of time.
Commonly used units: Volt (V)
Resistance method:
Apply the specified DC voltage and measure the resistance between the two measuring electrodes on the surface of the sample. The smaller the resistance, the better the conductivity of the sample!
Commonly used units: ohms (Ω)
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