(a) All equipment and material used in a disinfection and dechlorination system must meet the manufacturer's recommendations.     
      (b) A 150 pound cylinder must be stored vertically and secured by a clamp or chain to prevent it from falling over. A one-ton cylinder must be stored horizontally on trunnions.     
      (c) Measurements. A gaseous chlorine and sulfur dioxide system must have a scale designed for determining the amount of chemical remaining in the connected cylinders.     
      (d) Pressure Pipe Systems for Gas Transport.      
        (1) Gas transport pressure pipes must be at least equivalent to Schedule 80 black seamless steel pipe. Gas transport fittings must be at least equivalent  to 2,000 pound forged steel fittings.       
        (2) The use of polyvinyl chloride (PVC) in a pressure pipe system is prohibited.       
        (3) A one-ton cylinder system must use a gas filter upstream of a pressure-reducing valve.       
        (4) A pressure pipe system must have a pressure-reducing valve if:                  (A) the system has more than 20 linear feet of supply pipes;                   (B) the system is a gaseous sulfur dioxide system with a heating blanket; or                   (C) there are pressure pipes on the discharge side of an evaporator.         
        (5) A pressure pipe on the gas discharge side of an evaporator must have a rupture disk and a high-pressure alarm to  warn wastewater treatment facility staff of disk rupture.       
        (6) A gas pipe entering a chlorinator or sulfonator must have a heated leg drop sediment trap.       
        (7) A gaseous sulfur dioxide system must have a seat and stem constructed of material with corrosion resistance and brittle strength at least equivalent to 316 stainless steel.       
        (8) A gaseous chlorine system must have at least the equivalent of a Monel® seat and stem.       
      (e) Pressure Pipe Systems - Liquid Transport.      
        (1) The use of PVC in a pressure pipe system is prohibited.       
        (2) The manifolding of one-ton containers for simultaneous liquid chemical withdrawal is  prohibited.       
        (3) A liquid pipe system must include a rupture disk, a pressure switch to warn wastewater treatment facility staff of disk rupture, and an expansion chamber.       
      (f) Vacuum Pipes.      
        (1) Vacuum pipes and fittings downstream from a vacuum regulator must have corrosion resistance equivalent to PVC or 316 stainless steel.       
        (2) A vacuum pipe must have socket joints.       
      (g) Diffusers. The minimum velocity through any chlorine or sulfur dioxide system diffuser must be at least 10 feet per second. The engineering report must include calculations that verify this requirement is met, unless a diffuser has a mechanical mixer.     
     Source Note:        The provisions of this §217.279 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254