Neutralizers and Dilution Tanks

7.4.4.1.(1)

Where a fixture or equipment discharge sewage or waste that may damage or impair the sanitary drainage system or the functioning of a sanitary sewage works or sanitary sewage system, provisions shall be made for treatment of the sewage or waste before it is discharged to the sanitary drainage system.



Neutralizers are installed in acid waste piping systems and. They use limestone chips which are a natural alkali to reduce acid level of waste.



A dilution tank reduce the pH of the corrosive waste by the process of diluting it with large quantities of water.



Some dilution tanks are fitted with a cold water inlet. This connection helps to maintain an acceptable pH level by allowing a flow of cold water into the tank. However, it also create a cross connection which is considered to be in the range of high, or severe. There are two different methods of protecting this type of connection. In the first, an air gap could be installed and in the second, a reduced pressure principle backflow prevention device (RPA).



reduced pressure principle backflow preventer


7.2.10.10.(1) Except as provided in Sentence (2)  back-siphonage preventer and backflow preventers shall be certified to ...(Read the Code.)


7.4.4.4.(1)

Where a fixture or equipment discharge corrosive or acid waste, it shall discharge into a neutralizing or diluting tank which shall be connected to the sanitary drainage system through

  1. a trap, or



Connection of a neutralizer through a trap


  1. indirect connection



Installation of a neutralizer through a indirect connection


7.4.4.4.(2)

Each neutralizing or diluting tank shall have a method for neutralizing the liquid.


Fixtures Connections into an Acid Neutralizer or Diluting Tank

  1. Gang-trapping



Ganged-trapped sinks discharging through a neutralizer


  1. Individual Traps and Vents



Individual traps and vents for sinks discharging through a neutralizer


Trap Seals

7.2.3.1.(2)

The trap seal depth on fixtures draining to an acid waste system shall be a minimum of 50 mm (2").




Venting

7.5.4.4.(1)

Vent connecting to the corrosive drain piping or diluting tank shall extend independently to and terminate to an open air. (See Appendix A.)


7.5.4.2.(6)

Where an acid  waste dilution tank is installed, it shall be provided with a vent pipe connected at the top of the tank and that is sized in accordance with Article 7.5.6.5..


7.5.6.5.

  1. Where the diameter of an inlet pipe to a sanitary sewage tank is
  1. 5" or larger, the diameter of the vent pipe from the tank shall be at least 4", and
  2. less than 5", the diameter of the vent pipe from the tank shall be the greater of,

i) 1 1/4", and

ii)one trade size smaller than the inlet pipe.



Diluting Tank Venting


Pipe Materials

7.2.1.2.(2)

Materials and equipment used in a drainage system where excessively corrosive wastes are present shall be suitable for the purpose.

7.2.8.1.(1)

  1. Pipes and fittings to be used for drainage and venting of acid and corrosive wastes shall conform to
  1. ASTM A518M, "Specification Corrosion-Resistant High-Silicon Iron Castings".
  2. ASTM C1053, "Specification for Borosilicate Glass Pipe and Fittings for Drain, Waste, and Vent (DWV) Applications".
  3. CAN/CSA-B181.3, "Polyolefin Laboratory Drainage Systems".
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