... 6.working principle: a. low pressure difference condition, gate main through stem external force andguide pad/, its seal face and ... seal adopt double seal structure type, soft seal + metal seal, metal sealing layer effective protection soft sealing layer, increase the ... face: soft seal such as Ceramic ,rubber,PTFE and Metal seal.5. Packing: PTFE, reinforce Graphite etc;ActuatorsHand wheelpneumaticBevel ...