Textile Products Sweating Guarded Hotplate Testing Principle Analysis

Sweating guarded hotplate testing is commonly used testing method in clothing and apparatus industry for textile products heating or humidity resistance performance. Textile features testing plays quite practical and significant role in textile industry. 

Textile products sweating guarded hotplate testing principle: 
Sample is placed on electronic heating experiment board, at the same time, experiment board and the protecting board at bottom should be kept with the same temperature so that heating loss of electronic heating experiment board only due to sample itself; the wet air can flow parallel in the surface. After the experiment environment is being stable, we can calculate the sample heating resistance by way of its heating flow. 

For wet resistance, we should cover electronic heating experiment board with film which is permeable to air rather than water. The water goes through film in the form of steam after evaporated and thus there is no liquid water contacting samples. After the sample is placed on the film and under the condition that the heating of electronic heating board needed is ensured, we can test the heating flow sample wet resistance together with the exerted steam pressure.

 

For more sweating guarded hotplate or textile testing instruments information, QINSUN Instruments are ready for help.

The Comparison of New and Old Sweating Guarded Hotplate Testing Standards

In China textile industry, the earliest sweating guarded hotplate testing standard is GB/T11048-1989 which uses flat plate heat insulation device for insulation test. This method played positive role but it has following defects because of the technical limitations.

                                        sweating guarded hotplate

1.      The insulation rate is so different from that used by the international standard that the testing result couldn’t be exchanged.

2.      The concept of“insulation”has huge limitations, while thermal resistance can express textile heat transferring performance which is quite close to human physical comfort. 

3.      There are huge differences of insulation rate and thermal resistance in windless and windy environments. Thermal resistance reduces when there is wind, while the insulation rate rises which turns out to be opposite to the actual situation. Thus insulation rate is meaningful only in a certain situation.

                                                sweating guarded hotplate testing

The earliest sweating guarded hotplate testing method is ISO11092 which was formulated on the basis of flat plate tester developed by German scientists. It was released in 1993 and has been used today. ASTM F1868 is similar to it and there are several differences on testing environment and specifications.

China lately sweating guarded hotplate testing method is GB/T 11048-2008 and the main testing method A is the same as ISO11092; while method B-flat plate testing standard was used in some special situation.

 For more textile testing instruments information, please visit QINSUN Instruments-China professional textile testing equipment manufacturer. We are ready for help.

Critical Limiting Oxygen Index Test Apparatus Instruction

Critical limiting oxygen index tester is mainly used to measuring a variety of materials such as woven fabrics, rubber, plastic, foam, wood and other polymer materials. It consists of a sample holder, a combustion cylinder, flow meter, gas supply and control system.

Sample holder: sample holder is to support the vertical specimen in the center of the combustion cylinder. According to the standard provisions,  for the self-supporting material, sample holder should be at least 15 mm away from the nearest flaming spot; while for the non-self-supporting material such as a film or sheet, we should use a frame with vertical side to support, and mark lines on 20 mm and 100 mm to the top of frame. The holder and supporting frame should be made smooth in order to reduce disruption updraft.

     

critical limiting oxygen index test apparatus

 Combustion cylinder: This part consists of heat-resistant glass cylinder which is fixed to the base and can import oxygen & nitrogen gas mixture composition. Critical limiting oxygen index test apparatus standard combustion cylinder height is of (500 ± 50) mm, and the inside diameter (75 ~ 100) mm.

Gas source: Generally we use oxygen and nitrogen whose content should be more than 98% as the gas source.

Timer: Precise stopwatch measuring time can be up to 5 min with the accuracy of ± 0.5s.  Exhaust ventilation systems: material burning gives out poisonous gas thus smoke ventilation system must be installed to spread the smoke and gas. But the wind speed should be not too fast in case that gas flow rate and temperature in combustion cylinder or even testing accuracy be affected.

Igniter: Composed of a metal pipe with the diameter of (2±1) mm which can connect gas flame standard. When the sample is being ignited, you can adjust the gas amount so that the flame can be ejected from the outlet vertically downwards (16 ± 4) mm. The combustion gas is supposed to be pure propane gas.

If you want to know more about Critical limiting oxygen index tester or other textile testing instruments, please visit our website or contact us at any time, we are ready to offer you good quality instruments and service.

What Influences Critical Limiting Oxygen Index Test Apparatus

1, Calibrate oxygen index text apparatus

Common used oxygen limiting index test apparatus uses an oxygen analyzer to directly measure the oxygen concentration and then display data. In order to ensure the accurate results, every time before testing, we have to calibrate it in accordance with the requirements and the procedure is carried out using the standard gas.

2, Use fume hood

There will be great amount of toxicity gas because of the material burning which can not only pollute the environment but also harm to human body, thus according to the standard, the test should be carried out in a fume hood.

3, Clean combustion residue

Oxygenindex test apparatus bottom base is filled with diameters of 3 ~ 5 mm glass beads with the filling height of 80 ~ 100mm to fully mix gas.

4, Sample requirements

There are strict requirements on various aspects of sample. To ensure test results accuracy, we should strictly ensure sample shape, size, orientation direction, surface and the internal conditions. 

 

Conclusion

Oxygen index test can be used for general quality control as a way to provide combustion characteristics of materials burning in the lab. But it cannot be used to assess the actual fire hazard while it can only be evaluated as an element of fire risks. Oxygen index test method has several advantages such as good repeatability, high accuracy, good reproducibility, ease of testing and wide application thus has become an effective means to evaluate the combustion level.

For more information of oxygen limiting index test apparatus, you can visit www.qinsun-lab.com or contact us at any time. QINSUN Instruments is China professional textile testing instruments manufacturer.