Puracon Mobile M200: Tell You When to Change Your Filter Cartridge(s)

Anyone who has operated a breathing air compressor knows the biggest mystery is when to change the filter cartridge(s).  If you change them too often, you’re wasting money. It’s like throwing away a light bulb before it’s burned out. If you wait too long to change them, you stand the chance of passing moisture into your scuba tanks and regulators, as well as possibly filling your tanks with “bad gas.”

One of the primary functions of the filter cartridge is to remove moisture from the air processed by the compressor. Once the moisture removal media in the cartridge is saturated, the filter is spent and should be replaced immediately.

Filter life is determined by the temperature of the air being processed. Warm air holds more moisture than cooler air, so if you are operating the compressor in a warm environment, your filter life will be shorter.


So how should you know the right time to change the filter cartridge?

  • Compressor manufacturers usually provide a calculated estimate of filter life (processing volume) based on standardized conditions (20°C/68°F), with a correction table for other temperatures. The operator would need to keep a detailed log of the ambient conditions present while the compressor is running AND make continuous calculations on how the conditions affect the filter life. This method is theoretically daunting and practically impossible to perform accurately.
  • Another method is to use an automatic timer and calculate based on the worst case ambient conditions. This method should ensure safe gas is produced, but will likely have waste as the cartridge(s) will be replaced before reaching capacity.


The Puracon M200 is a small, portable monitor that can be easily installed between the fill valve and tank valve. It measures the moisture content in the air being processed in REAL TIME and displays the value on a high contrast LCD display. The operator can visually verify the air going into the scuba tank is within the acceptable range.

Processed air with good filtration typically has a moisture content of 10-15 mg/m³. This value will remain fairly constant until the filtration reaches saturation, at which point, it will climb quickly since the filter can no longer remove moisture from the air.

Should the moisture content rise above 25 mg/m³, a red LED light alerts the operator to change the filter cartridge immediately.

The Puracon monitor can be used with ANY breathing air compressor. You can even take it with you on trips to verify the moisture content in the air provided by a resort. The monitor is powered by 2 AAA batteries that can be replaced by the user.