Anti-tempered anti-return air unit (dry-proof devices) This device is a pipe for coal mine gas explosion and combustion flashback, back to the gas, but also has a special anti-return function device is to prevent tempering device the upgrading of products. The explosion-proof control device and gas extraction and utilization of common belonging prerequisite of security infrastructure. Suitable for installation in gas output pipe system, usually installed at a distance closer to the user or the location of the gas pump, protect mine down, drainage pump station and the user's security. Length: 1550 ~ 2400mm copper mesh layers: 6 layers copper network diameter: DN400 ~ DN1200 Weight: 310 ~ 1550kg Note: You can according to user requirements, custom design and manufacture of anti-tempering device structure of the product is simple, safe and reliable operation. Pumping gas in the course of their work, the device in the gas pressure inside the cover to open, in normal working condition; when no methane gas delivery, the device cover under the force of the counterweight lever pressed the mouth into the trachea, which can prevent Gas loopback; same time, when the explosion occurred, the same clamping device cover the mouth into the trachea, the pressure-proof plastic sheet can be rushed to open, in order to achieve the purpose of explosion relief, thus effectively protecting Inoue underground, drainage pumping equipment and user security. Model FFQ-1 FFQ-2 FFQ-3 FFQ-4 FFQ-5 FFQ-6 FFQ-7 FFQ-8 FFQ-9 FFQ-10 FFQ-11 FFQ-12 FFQ-13 FFQ-14 FFQ-15 FFQ-16 FFQ -17 Length (mm) 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2070 2140 2210 2280 2250 2320 2400 connecting tube diameter (mm) 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 steel mesh layers (n) 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 NM wire diameter (mm) 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 mass (kg) 310 330 360 400 450,510,580,660,750 85,096,010,801,180 1,290,140,015,001,550