How to Make a Axial Fan Survive 1 Year in 99% Humidity at 25°C?

[Richard1130]

Hello everyone,

I'm currently testing the durability of EC fans in high-humidity environments and I'm looking for advice or suggestions on how to improve performance.

Here’s my setup:

Fan model: 80x80x38mm, EC 48V, Plastic body, and impeller

Protection: Shaft core sealed with waterproof potting compound

Test conditions:

Group A: 3 fans in a chamber with 99% humidity, 25°C

Group B: 3 fans in a chamber with 25% humidity, 25°C

Goal: Continuous operation for 1 year

Result: The 3 fans in the 99% humidity chamber began to fail one by one after around 200 days of operation.

I suspect moisture is still penetrating into critical parts of the motor or bearings despite the waterproof potting. Has anyone dealt with similar conditions? Any tips on structural design changes, coating methods, or material choices to improve long-term humidity resistance?

Your suggestions or any shared experience would be greatly appreciated! 

https://www.hdhfan.com

[wraper]

I'd avoid using ball bearing fans for this.

[Richard1130]

Indeed, upon disassembly, we found signs of rust on the ball bearing.

[thm_w]

What do you mean by "waterproof potting compound"? Its a cured silicone? If so there will still be a gap for the rotating element, you'd need a o-ring seal or something more advanced.

But instead of doing that, why not just look at off the shelf IP55, IP65, IP66, etc. rated fans?
https://yccfan.en.made-in-china.com/product/WxyUwKAPgYka/China-Waterproof-IP66-24V-120X120X25-Cooling-Fan.html

The manufacturer might tell you what kind of tests they run, if the PCB is potted, etc.
Another option would be to use a magnetic coupling, but, thats probably only needed for actual water pumps.

[TERRA Operative]

I remember years ago when I was working as an electrician, we would source fans (Papst etc IIRC) from RS Components that were environmentally 'hardened' (I don't remember the actual nomenclature) when we replaced the cooling fans in outdoor kiosks (think things like the security beeper boxes for boom gates and the like).

They seemed to last a long time in the humid subtropical climate of Brisbane, Australia.

[amyk]

Pack bearings with grease.

[Richard1130]

The waterproof potting compounds are materials used to encapsulate electronic components. In fact, the waterproofing is very good, but I don't know how moisture can get in. Thank you for the advice tho.

[Richard1130]

Thank you for the advice.

[tooki]

The waterproof potting compounds are materials used to encapsulate electronic components.

Right. Potting compound is a type of sealant for non-moving parts. But the part that rusted is the ball bearings, which aren’t potted. (And can’t be; if you potted them they wouldn’t be able to move.)

In fact, the waterproofing is very good, but I don't know how moisture can get in. Thank you for the advice tho.

Well clearly the waterproofing is not very good. 

Why not ask a reputable fan manufacturer about fans for a very high-humidity application? This is hardly an unusual situation, all things considered. Just make sure it’s a fan manufacturer that doesn’t only specialize in PC fans. You want a company like Papst that makes fans and motors for all kinds of applications, including refrigeration, HVAC, and industrial stuff.

[Tina wang]

Your test requirements are very similar to those of one of our German customers. You can choose a more professional fan from HDHFAN.https://www.hdhfan.com/

[wraper]

At 25^oC you don't even need ball bearings for long life. Sleeve bearings will last a long time at such temperature, not to say there are other longer life variants such as Sunon Vapo/Maglev, FDB bearing and similar which prevent lubricant loss and have similar or even longer lifetime than ball bearings unless operated in hot environment.

[CatalinaWOW]

While I agree that ball bearings probably aren't required in this application, many rust resistant versions of ball bearings are available.  Stainless steel, plastic and ceramics with variants in each of those major categories.  One thing that is overlooked is that rust resistance must be built into all components.  Things like retainers, shields and seals, not just the balls and races.   This will also apply to bushed bearings.  The bushing can be rust resistant, but if the shaft is not also resistant failure can come more quickly than expected.

Another thing which tends to limit life in hot humid environments is mold.  The usual approach to controlling that is sealing as you are doing, and fungicidal additives to materials.  I don't know if or how that is done these days, but suspect it involves some very cautious navigation between environmental regulations and effectiveness.

[Tina wang]

Good idea

[BrianHG]

Thick water-resistant lithium based grease.

However, only expect around 1-2years if you run the fan continuously in that 99% humidity environment.

[coromonadalix]

you have ceramic / diamond strength based bearings

[Coordonnée_chromatique]

Hello everyone,
Result: The 3 fans in the 99% humidity chamber began to fail one by one after around 200 days of operation.
I suspect moisture is still penetrating into critical parts of the motor or bearings despite the waterproof potting. Has anyone dealt with similar conditions? Any tips on structural design changes, coating methods, or material choices to improve long-term humidity resistance?

Hello, you haven't say what failed !
 

[Jeroen3]

Are you using the fans in their intended orientation? Not all fans can be used in any orientation.

[SteveThackery]

Your suggestions or any shared experience would be greatly appreciated! 

https://www.hdhfan.com

Your test requirements are very similar to those of one of our German customers. You can choose a more professional fan from HDHFAN.

https://www.hdhfan.com/

Is there something weird going on here? Advertising for HDHFAN? Or just a mistake?

[CaptDon]

You buy a fan with a completely sealed motor which drives the fan through a magnetic coupling similar to pumps made for toxic or hazardous materials. The support bearings for the fan are also completely sealed. Look at the typical old style car air conditioning compressor which has a shaft to the outside world but contains freon internally to an idle pressure of at least 40PSI. The magnetic coupling is in common use in chemical stirrers and fish aquarium filters but is also available for fans used in explosive environments. Price you ask, about the same as a used car!

[amyk]

Is there something weird going on here? Advertising for HDHFAN? Or just a mistake?

If it's advertising they are doing it badly, as they are implying that their fans fail quickly and need help from others to try to fix it...

[SteveThackery]

If it's advertising they are doing it badly, as they are implying that their fans fail quickly and need help from others to try to fix it...

Yeah, I agree. I think @Tina wang didn’t realise the OP had https://www.hdhfan.com as his sig.

[alpher]

In my experience (beit at a little higher temperatures ~35C and humidities of 90%+) no axial fan will last more that a couple of years at best. Just use what's proper at these conditions, a proper stainless steel blower (or moisture resistant plastic) with motor being outside of airflow.

[jh15]

Only a year? another to be thrown away or subscription serviced device?