Inner decoration materials of automotive, such as leathers, plastics, textiles and adhesives of binding materials, contain some volatile substances, which will be volatile rapidly especially when inner temperature increases in the sunlight. The fogging condenses on window or window screen of autos, would cause poor visibility and affect safety of driving. Moreover, some volatile substance is bad for health. To control the generation of volatile substance to an allowable range, fogging test to auto’s inner decoration becomes a necessity. Materials with exceeding fogging value must not be used for auto’s inner decoration.
Generally, Fogging test instruments are manufactured in accordance to standard DIN 75201, using reflectometric (A) method or gravimetric (B) method. Testing procedures are as follows: a sample is placed insidea specially made beaker, which is immersed in high temperature liquid bath. The glass or aluminum foil with a lower temperature on top cover of the beaker allows the substances to emit from the sample to condense on the cool surface. The opaqueness of glass plate is measured to obtain test result of method A. For the gravimetric method, the quantity of condensate that formed on aluminum foil is measured to obtain test results.
Fogging test instrument cannot be simply considered as a single tester. It consists of several instruments and many accessories. In addition, Fogging test comprises many procedures. This presents more requirements on fogging lab construction.
2. Environmental Requirements of Lab Construction
Fogging lab construction for auto’s inner decoration requires certain consideration for environment, humidity, dust, ventilation and light.
Specimen conditioning before testing as well as equilibrium of glass plate or aluminum foil after condensation require the temperature to be 23°C±2°C. Otherwise, fogging test results will be directly affected. Generally, Other procedures of test should be carried out below 30°C.
The glass plate after condensation requires the humidity to be 50%±6% for equilibrium.
Small particles in the air, such as dust, impose obvious influence on test results. The dust on surfaces of glass plate or aluminum foil directly cause fault test results. Thus fogging test lab should be equipped with corresponding dust collection equipment. Operators should often clean desktop, equipment and accessories with wet cloth. To minimize the dust inside lab, operators of fogging lab should wear insulation garment and special slippers. Irrelevant people should not enter the fogging lab without permission.
There are some pungent odors produced when test components and glass vassals are washed with organic solvents.The DIDP and DOP solvents for comparison are substances with slight toxicity, which require good ventilation inside the fogging lab. However, glass plate after condensation should be placed in air for equilibrium with gas flow inside fogging lab less than 1m/s, so that the opaqueness of glass plate is not affected. To meet such requirements, doors, windows and ventilation system should be closed to prevent airflow. In other ways, specimen heating, volatilization, condensation, specimen conditioning, and equilibrium of glass plate and aluminum foil can be carried out in different rooms.
Specimen conditioning, volatilization and condensation, equilibrium of glass plate and aluminum foil are sunlight forbidden. Therefore, it is preferable that the lab is in a sunless place or sunlight-proof with reliable curtain and door screen.
3. Basic Facility of Fogging Lab
A well-functioned and conveniently-operated lab should be equipped with facilities below: experimental bench, cabinet, water source and water tank, power supply, air conditioning system, ventilating installation, tile floor (insulated) and porcelain treated wall, etc.
Experimental bench and cabinet are used to place equipment, operation accessories, agents and cleaning solvents.
Water source and water tank are necessities. A lot of cleaning work is done by water tank. An easy-to-use and well-designed water tank can greatly improve working efficiency, providing reliable guarantee to obtain accurate test results.
Air conditioning system and ventilating installation are used to secure regulation temperature and exhaustion of poisonous gas.
The well-treated floor and walls are favorable to prevent dust.
4. Instruments and Devices of Lab
Fogging lab for auto’s inner decoration needs many test instruments and operation devices, with some provided by fogging instrument manufacturers and some prepared by lab construction institution itself.
Generally, fogging tester manufacturers supply the following instruments and devices: heating tank, cooling device, specimen presser, beaker, fluorine rubber seal ring, cushion rubber locking ring, square glass plate, round glass plate, cover plate, square glass plate stand, round glass plate stand, specimen cutter, reflectometer, heat-carrying oil, DIDP, DOP, mat position gasket, reflectometer isolation pad and sponge, etc. Most of the above-motioned devices are supplied by domestic manufacturers and those provided by foreign manufacturers are slightly less. Some consumable solvents provided by manufacturers such as DIDP and DOP are bought by Lab part when running out.
Things prepared by lab side are: two 400mm-caliber desiccators, two stainless steel nippers, 120mm-diameer soft filter paper, one-off polypropylene gloves, glass cleaning agent, haze meter, 01 grade balance (gravimetric method), accessory frame, desiccant, distilled water, degreased cotton, wild-mouth bottle, hair brush, 50ml beaker, vassals to immerse glass bottles.
The above listed things are all necessities of fogging test.
5. Staff Training
In addition to the above-mentioned things, a well-equipped and complete lab should have highly-qualified operators, who should receive the following trainings: first, study various international and domestic standards for fogging test carefully. Keep in mind all the details involved in these standards. Second, study the instruction book of fogging test instruments carefully to obtain a comprehensive understanding of instrument structures, properties, operation methods and precautions. One thing to be specially noted here is that operators should pay great attention to the cleaning procedures and strictly abide by operating rules so that test failure caused by random operation can be avoided.
During the construction of an excellent lab, details of various aspects should be well treated. In the case of fogging lab, since more devices and complex operation procedures are involved, a higher demand for lab construction is especially raised. So long as we complete each process strictly according to standard specifications, we can undoubtedly construct an excellent fogging lab.