The difference between the upstream sealed automatic pressure relief valve seat and the double sealed valve seat of the fixed pneumatic ball valve The double piston effect valve seat does not have the automatic ground pressure function, so when no additional relief device is added, if the pressure in the middle chamber rises abnormally, the pressure cannot be released, which will have a certain impact on the safety of the valve. Therefore, the double piston effect valve seat can only be used in stable gaseous media (natural gas, air, ammonia, inert gas, etc.). When transporting liquid media, condensing media and unstable gaseous media, a pressure relief device must be set on the valve chamber. Since the double piston effect valve seat compresses the ball on both sides of the valve seat at the same time when working, the operating force loss is greater than that of the pneumatic ball valve with the self releasing valve seat.

Rubber joint is also called rubber pipe flexible joint, flexible rubber joint, rubber flexible joint, flexible rubber joint, high-pressure rubber joint, rubber shock absorber, compensator, etc. From the appearance, the appearance of the rubber joint is not very different, but the internal quality determines the service life of the rubber joint. Therefore, good rubber joints are very important. Here are five ways to identify the raw materials of rubber joints:
1. Medium weight increase test: samples can be taken from products, soaked in one or several selected media, weighed after a certain temperature, and guess the type of materials according to the weight change rate and hardness change rate. For example, after soaking in 100 degree engine oil for 24 hours, the quality and hardness change rate of NBR, fluororubber, ECO and CR are very small, while NR, EPDM and SBR have more than doubled in weight, greatly changed in hardness and obviously expanded in volume.
2. Combustion method: take a few samples and burn them in air. Investigate the phenomenon. Generally speaking, fluorogel, CR, and CSM are self extinguishing when they are out of fire. Even if the flame is ignited, it is much smaller than that of NR and EPDM. Of course, assuming careful investigation, the combustion state, color and smell will also provide us with a lot of information. For example, NBR/PVC adhesive blends, when there is a fire source, the fire will sputter as if there is water, and it will extinguish itself when it is away from the fire, with thick smoke and sour taste. It should be noted that sometimes the adhesive added with flame retardant but without halogen will extinguish from the fire, which should be further speculated by other methods.
3. Hot air aging test: take samples from the products and put them in the aging box for aging for one day to investigate the phenomenon after aging. Gradual aging can be used to gradually increase the temperature. For example, CR, NR and SBR will be brittle at 150 ° C, and NBR EPDM will be elastic. When it rises to 180 degrees, ordinary NBR will be brittle; The HNBR will also be brittle at 230 degrees, and the fluorine glue and silica gel still have excellent elasticity.
4. Measuring specific gravity: use an electronic scale or analytical balance, accurate to 0.01g, and add a glass of water and a hair. Generally speaking, the proportion of fluorine glue is the largest, more than 1.8, and the proportion of CR ECO is also more than 1.3. It can be considered that these glues are obviously larger.
5. Low temperature method: take samples from products and use dry ice and alcohol to create a suitable low temperature environment. Soak the sample in a low temperature environment for 2-5 minutes, and feel the soft and hard level at the selected temperature. For example, at - 40 ℃, the same high temperature and oil resistance excellent silica gel and fluorine gel contrast, silica gel is soft.