Glossary of Terms - "S"

Term Definition
Safety Inlet Valve

This is the same as the chlorinator inlet valve.

Solution Line

The water line into which a chlorine or sulfur dioxide solution is injected.


Due to the high concentrations of bacteria and other microbiological organisms in waste water, commensurate high concentrations of chlorine are necessary for proper disinfection. Treated waste water is discharged to tributaries through NPDES (National Pollutant Discharge Elimination System) outfalls, and an NPDES permit restricts the allowable chlorine concentration of the discharged water.  Sulfonators are used to inject measured amounts of sulfur dioxide into chlorinated waste water for the purpose of dechlorination.

Sulfur Dioxide Safety Precautions:
Sulfur dioxide gas is not considered to be toxic, but it is a respiratory, eye, and possible skin irritant. It can cause breathing difficulties similar to the symptoms of a chest cold.

All forms of sulfur dioxide gas must be used and handled with appropriate knowledge, care, and respect in order to eliminate the potential for unsafe conditions.

Sulfur dioxide gas is colorless and therefore is not easy to visually identify. It has a distinctive pungent odor that will alert the user of a leak in ample time before irritation can occur. It is somewhat denser then air and will sink to low-lying spaces.

Because of the density and expansion factors, sulfur dioxide containers should never be placed in direct sunlight or exposed to other direct or indirect heating sources!

It should also be noted that sulfur dioxide is corrosive to many common metals and other substances.

Supply Line Pressure

Water pressure of the water line which supplies water to the ejector, usually expressed in pounds-per-square-inch (P.S.I.). This pressure must be greater than the back pressure of the water system being chlorinated.


A device which is used to automatically change the supply of chlorine gas from an active cylinder which has just emptied to a full cylinder. The loss of vacuum from the empty tank causes a valve in the switchover device to change position, shutting off the gas feed from the empty tank and opening the inlet valve of the chlorinator on the full tank. Both single-point and multi-point applications systems use switchover devices.