Preparing Your RTO for Cold Weather

Refurbished Regenerative Thermal Oxidizers (RTOs)

Tips for Cold Weather RTO Use

Cold weather can impact the reliability of your RTO, especially during sudden temperature changes. These preventive maintenance tips will help you dodge some of the common faults that occur due to cold weather.

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Compressed Air

Dry compressed air is Priority #1 for reliable winter operation of your RTO

Regenerative thermal oxidizers (RTOs) typically use pneumatic air cylinders as well as pneumatic actuators driven by solenoid valves. Water present in the compressed air supply lines will cause problems when cold weather arrives. Pneumatic components have small orifices for flow/actuation control. Ice in the feed lines or components will block proper flow, leading to locked up components and RTO faults.

To ensure water does not form in the lines or the components, a desiccant dryer rated for -40°F dew point is highly recommended. Do not use a refrigerated air dryer; it will not provide a dew point low enough to protect against moisture and freezing in Canada and most of the USA.

regenerative desiccant style air dryer for RTO system
Regenerative Desiccant Style Air Dryer

Proper dyer operation is critical for RTO reliability. Follow the recommended maintenance schedule for your air dryer. Preventing moisture formation will protect against the kinds of nagging problems that appear once water is present in the system.

Moisture in your air tank or air lines indicates a potential problem with your air dryer. Drain your air tank periodically, especially before cold weather sets in. If moisture is present you’ll need to inspect and/or repair the airline and air dryer/desiccant, and troubleshoot your main air source upstream of the desiccant dryer. You should also activate all components to exhaust air through them, driving out any pooled moisture in the lines or components. Keep components active until no moisture is present in the exhaust. Don’t skip over the little-used pneumatic components in this exercise, as they are a prime moisture trap due to non-use. These tend to be problem components when the first freeze arrives.

regenerative thermal oxidizer air tank with drain valve
Air Tank w/Drain Valve
air solenoids and cylinders on poppet valves for regenerative thermal oxidizer
Air Solenoids/Cylinders on Poppet Valves

To protect against these issues now and in the future, stay on top of pneumatic component maintenance to keep them in proper working condition. Pneumatic seals tend to degrade even in dry air conditions. Follow the manufacturer’s maintenance schedules for rebuild or replacement of pneumatic components.

Persistent problem areas can possibly be addressed by applying heat tape or adding a weather cover over the problem component.

Pressure Sensing Lines

Moisture and debris buildup in sensing lines should be cleared out periodically

RTOs have many instruments to monitor and control operation, such as pressure sensors, gauges, and switches. Stainless steel or copper sensing lines connect the RTO to these instruments. Sensing lines are tapped into the RTO at various points, and may have varying levels of debris or moisture present. Poor connections or cracks in the sensing lines can allow unintended airflow in the lines, drawing in debris or moisture.

Over time, water and debris can affect instrumentation performance by causing intermittent faults, poor readings, and/or part failure.

A good practice is to periodically disconnect the sensing lines from the instrumentation (while RTO is shut down) and use a compressed air lance to blow compressed air back into the sensing line, driving any moisture and debris buildup back into the process duct or RTO. You should also periodically drain any drip legs on the unit to drive out accumulated moisture from the system.

regenerative thermal oxidizer instrumentation sensing lines with drip legs
Sensing Lines with Drip Legs

Sensing lines must be inspected regularly for cracks or excess vibration that can lead to splits/abrasion of the sensing line. Inspect the entirety of the lines and replace as necessary. Be sure all sensing lines are sloped, with a drip leg installed at the lowest point to trap moisture.

Panel Heaters

Ensure panel heaters are operational before cold weather arrives

Most OEMs will mount electrical or pneumatic enclosures on the RTO itself. Some panels will have components sensitive to very low (or very high) operating temperatures. These panels may have heaters to maintain a minimum temperature level. Panel heaters should be tested before cold weather arrives to make sure they’re working correctly.

electrical control cabinet with panel heater
Control Cabinet w/Panel Heater

Spare Parts

Parts failure is a reality – be sure to keep spare parts in stock

The best way to prevent downtime is to understand the life cycle of RTO components so you can replace or rebuild them before they fail. A good stock of spare parts is always a wise maintenance practice. Follow the spare parts recommendations in your O&M manual, and choose the spare parts level that meets your desired level of uptime.

All components have a life cycle and will eventually fail. Keeping a backup component on your shelf will ensure availability during preventive maintenance, and in case of an emergency downtime situation.

Scheduled Maintenance

RTOs, like any other industrial equipment, require proper maintenance

Follow your OEM’s inspection and maintenance guidelines provided in your operation and maintenance manual and vendor literature. Kono Kogs also recommends annual visits by a Kono Kogs technician for preventive maintenance. Our technician can identify and correct any issues before they become critical or result in unscheduled downtime for repair.

Kono Kogs offers a preventive maintenance program, KonoCARE, with plans for every budget.

Some of our clients want 100% uptime on their equipment, and we offer our Diamond level maintenance program to get them as close as possible to that goal. Diamond level is our most extensive PM support plan. It includes periodic remote monitoring of the RTO with weekly and monthly analysis of operating conditions to identify concerns before they become emergencies. Plus, we provide direct alarming to our service team if the unit goes off-line. Other clients just want a simple safety net to help their maintenance crew get their unit running as quickly as possible when it goes down, at the lowest cost. We have programs for both of these scenarios, and some in between.

Other Practical Guidelines

Keep your RTO running over the weekend when a cold snap is expected

If you typically shut your RTO down for a weekend or a long weekend during the holidays, consider keeping it running in a low flow (idle) mode if a cold snap is coming. Freeze-ups happen (and other faults happen) on re-starts of the RTO in these kinds of cold weather conditions. You and your crew do not want to be out in the cold first thing Monday morning troubleshooting, running heat guns and heat tape trying to free up frozen components.

The is little difference in utility cost to run an RTO at reduced flow compared to shutting it down for the weekend and reheating it Monday. Talk with Kono Kogs about your system. We can analyze the utility cost and provide a break-even estimate (i.e. 1.5 days) to allow you to make choices in given situations. You may even find that it makes sense to keep the RTO running every weekend regardless of outside temperature.

Rotary Valve Upgrade: Pneumatic to Electric Drive

One way to avoid pneumatic line freezing is to upgrade your pneumatic rotary valve to an electric driven valve? Check out this case study for the advantages possible with this upgrade.

For more guidance and an in-depth explanation of any of the above recommendations, contact our service team at or call 920-615-8804.

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