How to distinguish the type and material of the seal ring

Our O-ring production has a variety of materials, there are Ding Qing O-ring, fluorine rubber O-ring, silicone O-ring, EPDM O-ring, neoprene O-ring and so on, so how to identify these materials?

1, resistance to media weight gain experiment

Can be purchased from the O-ring sample, after determining the temperature, soaked in the selected one or several media, after a certain time to weigh, according to the weight change rate, hardness change rate to infer the type of material. For example, soaking in 100 degree oil for 24 hours, Ding Qing, fluorine glue, neoprene quality and hardness change rate is very small, and natural rubber, EPDM weight more than double and hardness change greatly, volume expansion is obvious.

2. Combustion method

The sample is taken and burned in the air. Observe the phenomenon. In general, fluorine rubber, natural rubber will be extinguished after the fire, even if the fire is much smaller than EPDM. Of course, if you look closely, the burning state, color, smell will also give us a lot of information. For example, NBR/PVC and glue, when there is a fire source, the fire splashes, seems to have water, from the fire to extinguish, the smoke is thick and sour. It should be noted that sometimes the glue that is added with flame retardants but does not contain halogens will also extinguish itself from the fire, which should be further inferred by other means.

3. Hot air aging experiment

The sample is taken and placed in the aging box for one day to observe the phenomenon after aging. In order to be able to stage aging, you can gradually heat up. For example, at 150 degrees, chloroprene, natural rubber, SBR will be brittle, Ding Qing, EPDM and elastic. Rise to 180 degrees, ordinary Ding Qing will be brittle break; At 230 degrees, hydrogenated butyl will also be brittle, and fluorine glue and silica gel still have good elasticity.

4. Low temperature method

Samples are taken and a suitable low temperature environment is created with dry ice and alcohol. Soak the sample in a low temperature environment for 2-5 minutes, and feel the hardness of the O-ring at the selected temperature. For example, at -40 ° C, the same high temperature and oil resistance is very good compared with fluorine rubber, silicone will be softer.

5. Measure the specific gravity

A precision electronic scale, a glass of water, a hair. In general, the proportion of fluorine glue is the largest, more than 1.8, CR, ECO is also more than 1.3, the proportion is obviously too large can be considered these glue.

The above methods can only be a simple test of the composition of rubber, if you want a specific test report, you also need to send a special testing organization to test.