The C.W.T. External Loop Interface Explained

What is a C.W.T. External Loop Interface?

The ClearWater Tech, LLC. External Loop is a true dry contact interface designed to allow main power of the ozone generator to remain “ON” while only energizing or de-energizing the ozone reaction chamber(s). The term “dry contact” means the loop does not supply output nor except input voltages.

The function of the external loop is to interface the ozone generator to any control device. Some devices include:

• Pressure switch
• Vacuum switch
• Flow switch
• Float switch
• ORP controller
• PPM monitor
• Ambient ozone monitor
• Timer (both digital & analog)

How Does it Work?

Under normal operation the external loop will effectively interrupt the ozone output when the loop has lost continuity. When continuity through the external loop is restored, ozone output will continue.

Removable Dry Contact Loop

For continuous operation (not using an external control device),  a removable two-position plug with an 18AWG wire loop is supplied with the ozone generator. As long as the loop remains closed, ozone production will remain constant.

To interface a control device to the external loop, simply cut the 18AWG wire in half. Connect the control device to each leg of the external loop and you now have on/off control of your ozone generator’s ozone production. If the control device used supplies an output voltage, a single pole single throw (SPST) normally open relay may be used to create a dry contact interface (see diagram below).

The External Loop Interface

Warning: Supplying voltage to the external loop will not only cause damage to the ozone generator, but it will void the warranty as well.

-Authored by Brandon Turney, Service Technician, ClearWater Tech, LLC

What Should I Do With My Excess Ozone?

If you have ever been in a pump room when ozone is being made and it is not properly ventilated, you know the smell can sometimes be quite overwhelming. This can easily be avoided if you apply safe ventilation techniques.

There are several types of ozone destruction systems available, such as using ultraviolet light irradiation to decompose ozone as it passes, heating ozone to extreme temperatures (at or above 428 °F [220°C]) for several seconds, or sending the ozone through a catalytic destruct system. We will look at the most popular methods.

Three popular options for controlling off-gas

• Running a line to off-gas outside
• An ozone catalytic destruct system
• Activated carbon destruction method

The “run-a-line” Method

Ozone Catalytic Destruct System

The cheapest and easiest method is to simply run a length of ozone resistant (typically Teflon^®) tubing from a off-gas vent to a elevated location outside of the building. With the half-life of ozone being so short, the excess ozone will quickly revert back to oxygen and be vented to ambient air.  If this is not an option, for example, you are in a basement that has no windows and you can’t easily run tubing under a door outside, then the next option would be a better solution.

If using this method, there are some important points to remember.

• Make sure your line is free of debris or obstructions. Any blockages will result in back pressuring your tank and therefore causing loss of vacuum at the injector.
• If you are operating your equipment in freezing conditions, it is advisable to move your tubing to a location that is not affected by the extreme temperature. As with most auto off-gas systems, there will be condensation build up in the lines. If that water freezes, blockages may occur.

Ozone Catalytic Destruct System

The most common method is the catalytic destruct system, which uses Carulite^®, a combination of Manganese Oxide and Copper Oxide. These types of destruct systems might also contain some type of heating element to burn off the ozone as it passes to be extra sure of ozone decomposition as well as an additional “water trap” (pictured) to help capture moisture before it can reach the dry media of the destruct.

Activated Carbon Method

Activated Carbon is also an excellent way to eliminate excess ozone. The most important point to remember when it comes to using activated carbon to destroy ozone is to always use a metal container (preferably stainless steel) to hold your carbon media. The reason for this is because the process of passing ozone gas through carbon causes the carbon to heat up and reach extreme temperatures. If you use a plastic container to house your media, you greatly increase your risk of it melting and causing an ozone leak, or worse yet, starting a fire. So, when using activated carbon, keep in mind, use a metal container.

-Authored by Brandon Turney, Service Technician, ClearWater Tech, LLC