Risks with humidifier pad PMA

A humidifier pad module is a subsystem in the humidification system and is inserted into the OEM humidifier housing. Not all approved parts are created equal when it comes to compatibility, safety, and performance of aircraft humidification systems. In this article, you will learn the importance of using original pads to maintain the highest quality and safety.
Risks with humidifier pad PMA vs original from CTT Systems
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We at CTT Systems are the leading authority in this field as the sole OEM supplier of humidification systems. We have the best application knowledge and are uniquely positioned to highlight the risks of using Parts Manufacturer Approval (PMA) humidifier pads instead of Original Equipment Manufacturer (OEM) parts. 

But don´t just trust our words – read what the producer, world-leading pad manufacturer Munters´, says about the importance of using the original and certified aviation GX60 pads. 

Munters' standpoint

“Given the considerable differences in material, manufacturing processes, testing, and certification, Munters strongly advises against using humidifier pads with GX30 material in the CTT Systems Humidifiers.

The GX30 pad material is not developed, produced, or tested for aviation, unlike the GX60 pad material certified for aviation used in CTT Systems Humidifiers. Ensuring that approved materials like the GX60, developed for the specific way the humidifiers wet the pad material, are used is essential for maintaining the highest air quality and safety.” 

The core issue: OEM vs. PMA

CTT Systems OEM pad parts are developed specifically for the application and are 100% compatible with the system, meticulously tested and certified to meet rigorous safety and performance standards established by aircraft manufacturers and aviation authorities. 

In contrast, PMA parts, while tested, normally only need to meet basic environmental standards and do not undergo comprehensive functional testing for specific systems like those of CTT Systems. This discrepancy can lead to safety and performance issues. 

A closer look at the materials: GX60 vs. GX30

CTT Systems original pad with approved GX60 material

CTT Systems’ original humidifier pads are designed with GX60 material—a ceramic/active-carbon glass fiber composite specifically developed for aviation applications. This ensures optimal control over odor, bacteria, and pathogens like Legionella. Top aircraft manufacturers and relevant authorities, including the FAA and FDA, specified the tests needed to approve the CTT Systems pads. 

PMA pad with GX30 material

Conversely, the PMA pads utilize GX30 material, a glass fiber composite historically used only for static industrial applications. The GX30 material is discontinued outside the US and, more importantly, has not been approved by major aircraft manufacturers or undergone all the rigorous testing necessary for aviation use. 

Furthermore, the GX30 pad is designed to remain wet at all times during operation. The aircraft humidification system does not rinse water continuously through the pad but instead periodically sprays it with water. 

PMA's potential safety implications

The humidification system is integrated into the duct and is part of the aircraft environmental control system (ECS). A blocked pad could compromise airflow to the flight deck, potentially leading to unsafe levels of carbon monoxide or carbon dioxide or insufficient ventilation of hazardous smoke. 

Munters´ study and findings of GX60 vs GX30

Munters, the world leader in evaporative cooling pad material, has conducted a comprehensive comparison between GX60 and GX30 media types, highlighting significant differences for this particular field of use in aircraft humidification systems: 

Performance efficiency

GX60 has a lower pressure drop, making it more effective in systems where airflow resistance is a concern. 

Material composition

GX60 is a ceramic/active-carbon composite media with minimal organic compounds, allowing it to operate effectively across a wider pH range (3-11). This makes GX60 suitable for varying water treatment conditions without degradation. 

GX30, primarily composed of glass fiber, has a narrower pH tolerance (6.5-8.5), limiting its applicability. 

Odor and bacteria control

GX60 includes active carbon for enhanced odor control and is tested against Legionella bacteria, ensuring safety against air and waterborne pathogens. 

GX30 lacks these features, posing a risk in environments where odor control and bacterial safety are critical. 

Structural integrity

GX60’s rigid structure prevents collapse under its weight when wet. This feature ensures consistent performance and durability of GX60 in various operational conditions. 

GX30 offers less structural stability. 

Fire safety and global use

GX60 meets the highest fire safety standards, EN 13501-1 Class A1,  and is utilized globally. 

GX30 does not meet this standard. 

Water treatment compatibility

GX60 can handle oxidizing chemicals used in water treatment. 

GX30 does not support such treatments, which can be a limitation in maintaining hygiene standards in humidification systems. 

The conclusion from Munters' study

The study clearly outlines why GX60 media is superior to GX30, especially for critical applications like aircraft humidification. GX60’s enhanced material properties, ability to control odors and bacteria, structural integrity, and broader chemical tolerance make it a preferred choice for aviation and other sensitive environments. 

Munters' recommendation

Given the considerable differences in quality, testing, and certification, Munters strongly advises against using non-OEM humidifier pads. The safety, performance, and compliance risks associated with PMA pads do not justify the potential cost savings. Ensuring using OEM-approved materials like the GX60 pads is essential for maintaining the highest air quality standards and safety onboard. 

In-depth reading

Humidifier Onboard with original pads
– developed for aviation standards and OEM compliance 

What to do next

➔ Contact us for more information about optimizing humidity in your aircraft 
➔ Read the article Humidifier Pad Assy by CTT is based on unique IP to obtain OEM compliance  
➔ Read more about CTT Systems Original Humidifier Pad GX60
➔ Read about our Humidifier Onboard 


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