Effective against liquid chlorine and chlorine butter - a pressure reducing valve with the “CondiChlor 10K” chlorine filter

Chlorine gas is a hazardous substance. This explains why chlorinators in accordance with DIN 19606:2010 work in a total vacuum. Chlorinators are subject to very strict safety regulations, both during their installation, the room set-up, operation, servicing and maintenance. Possible hazards pose a threat to people, the environment and the system itself. As such, the dosing of chlorine gas places high requirements on the machinery and materials. The best protection against hazards is their avoidance or minimisation.

 

In addition to impurities in the chlorine gas (which should be ruled out by the quality specifications of DIN EN 937), liquid chlorine has proven itself to be the most common source of malfunction.

 

The line system from the chlorine tank to the vacuum regulator is under the positive pressure from the chlorine tank. This pressure is dependant on the temperature (see graphic).

 

State changes in the chlorine result from changes to the temperature or pressure. Cooling (see arrow 1) liquefies gaseous chlorine; pressure reduction (arrow 2) converts liquid chlorine to gas form. At 20 °C, the system has a positive pressure of c. 5.7 bar, a pressure at which gaseous chlorine liquefies. These situations occur, for example, due to extreme temperature variations during day and night. Chlorine drums or chlorine cylinders have a large mass which cool down at night more slowly than pipes and devices. The line is cooler and fills with liquid chlorine.

To avoid condensation in temperature ranges down to 0 °C, the pressure must be reduced to ≤ 2.5 bar. This is the approach of the “CondiChlor”.

How else can liquid chlorine penetrate the dosing system?

As the curved pipe in the drum can contain liquid chlorine from transport, the valve for gaseous removal can issue up to 100 ml liquid chlorine during the change of the chlorine tank.

Liquid chlorine can also result from condensation as the result of temperature and pressure differences during operation.

If leaks or temporarily open connections allow the penetration of moist air, the strongly hygroscopic chlorine gas will be converted to hydrochloric acid. The aggressive hydrochloric acid corrodes the lines and fittings and even attacks plastic parts which are otherwise resistant to dry chlorine. The corrosion products result in soiling and storage of chlorine butter. Chlorine butter consists of the reaction products of condensed / hydrated chlorine, air humidity, hydrochloric acid and particulate impurities from the corrosion of steel and brass such as iron (III) chloride, zinc, nickel, copper chloride and their hydroxides and oxides. This paste-like mixture is highly corrosive and can cause malfunctions and damage to the device. It is therefore vital to avoid both the development and the penetration of fluid chlorine. The “CondiChlor” fulfils the following tasks:

Reduction of the chlorine pressure, in order to prevent the development of condensate in subsequent pipes and devices.

Separating dirt particles from gaseous chlorine through ceramic filters.

The separation, collection and (optional) evaporation of small volumes of condensed chlorine.

Intercepting 150 ml liquid chlorine, the “CondiChlor” prevents it from penetrating the system and thereby the development of dangerous chlorine butter. The moisture eliminator collects the liquid chlorine before it can damage the subsequent devices. An optional heating collar is available which vaporises liquid chlorine immediately. The “CondiChlor” prevents malfunctions and safety risks from leaks and expensive repairs.