HJ/T 252-2006 Specifications for environmental protection product Middle and fine bubble diffusers

CJ/T 3015.1-1993 CJ/T 3015.2-1993 Flow rate and oxygenation performance of water purifiers CJ/T 3015.4-1996 Openable middle and fine bubble diffuser for wastewater treatment GB 3452.1-1992 Fluid systems—Sealing devices—O-rings—Inside diameters, cross-sections, tolerances and size identification code GB/T 3452.1-2005 Fluid power systems—O-rings—Part 1:Inside diameters, cross-sections, tolerances and size identification code GB/T 1220-1992 Stainless steel bars GB/T 1220-2007 Stainless steel bars GB/T 13306-1991 Plates GB/T 13306-2011 Plates GB/T 3672-1992 GB/T 5836.1-1992 Unplasticized polyvinyl chloride pipes for drainage in buildings GB/T 5836.1-2006 Unplasticized poly (vinyl chloride) (PVC-U) pipes for soil and waste discharge inside buildings GB/T 5836.1-2018 Unplasticized poly(vinyl chloride)(PVC-U)pipes for soil and waste discharge inside buildings GB/T 5836.2-1992 Unplasticized polyvinyl chloride fittings for drainage in buildings GB/T 5836.2-2006 Unplasticized poly (vinyl chloride) (PVC-U) fittings for soil and waste inside buildings GB/T 5836.2-2018 Unplasticized poly(vinyl chloride)(PVC-U) fittings for soil and waste discharge inside buildings GB/T 699-1999 Quality carbon structural steels GB/T 699-2015 Quality carbon structure steels GB/T 9476