In industrial settings such as the petroleum, chemical, and pharmaceutical sectors, environmental humidity control has long 

transcended the realm of mere “comfort”; it directly impacts process stability, product quality, and even the safety of lives 

and property. However, when corrosive gases or flammable and explosive dust are present in these environments, an industrial 

dehumidifier with refrigeration capabilities is no longer merely a standard temperature-control device, but rather a “high-risk 

piece of equipment” that must strictly adhere to multiple safety standards. If companies select equipment based solely on 

dehumidification capacity or energy efficiency ratio while neglecting core safety metrics—such as electrical explosion protection, 

corrosion resistance of materials, and spark prevention in moving parts—they may well pay a heavy price for what appears to be 

a routine equipment deployment, ranging from production shutdowns and rectification measures to major accidents.

I. Electrical Explosion-Proof Rating: A Non-Negotiable “Hard Threshold”

In petrochemical or fine chemical workshops, volatile organic solvents, flammable gases such as hydrogen and methane, and 

flammable and explosive substances like aluminum powder, magnesium powder, and sulfur dust often exist in vapor or suspended 

states. When a dehumidifier with refrigeration capabilities is in operation, processes such as compressor start-up and shutdown, 

relay switching, and the operation of temperature sensors may all generate faint electrical sparks or hot surfaces. If the explosion-proof 

rating of the equipment’s electrical system does not match the classification of the on-site hazardous area, this dehumidifier 

effectively becomes a latent “ignition source.”

II. Corrosion Protection for Heat Exchangers and Structural Components: The Long-Term Battle 

Against “Hidden Corrosion”

In chemical and pharmaceutical environments, corrosive media such as chlorine, hydrogen sulfide, ammonia, and acidic volatiles 

are ubiquitous. Even at extremely low concentrations, prolonged exposure puts the dehumidifier’s core components—the 

evaporator and condenser fins—directly at risk. Ordinary hydrophilic aluminum foil fins may develop pitting corrosion within 

a matter of weeks, leading to a sharp drop in heat exchange efficiency and abnormal refrigerant pressure, which in turn can 

cause compressor overload or frequent activation of thermal protection. Even more dangerous is that corrosion debris from 

the fins may flow into the drainage system along with condensate, causing localized water contamination or triggering secondary 

reactions with residual chemical substances, thereby posing a risk of environmental compliance violations.

In response, industry-recognized mandatory requirements include: heat exchanger fins must be treated with a corrosion-resistant 

coating—such as anodization or electrostatic epoxy resin spraying—and the coating’s thickness, adhesion, and salt spray test 

duration must meet stringent standards exceeding specific time thresholds; for the shell’s sheet metal components, stainless 

steel or aluminum-zinc-coated steel should be used, combined with outdoor-grade powder coating. It is worth emphasizing 

that corrosion protection is not as simple as “applying a coat of paint”; the key lies in the bonding process between the 

coating and the substrate, as well as additional protection for vulnerable areas such as capillary tubes and weld points. 

Once microcracks form in the coating due to thermal expansion and contraction, corrosive gases may penetrate along these 

cracks, causing internal copper tubing to leak. At that point, not only will refrigerant loss render dehumidification ineffective, 

but if the leaked refrigerant comes into contact with high temperatures or open flames, it may decompose and produce 

toxic gases, posing a secondary safety threat.

III. Fans and Moving Parts: Spark-Proof Design Is the Last Line of Defense

In explosion-proof dehumidifiers, the selection of fan impellers is often underestimated. In fact, when a fan rotates at high 

speed, friction or impact between the impeller material and hard particles remaining in the air duct—such as crystallized 

salts or metal debris—is sufficient to generate incandescent particles or sparks. In environments at risk of dust explosions, 

this risk increases exponentially. Therefore, compliant equipment must use spark-proof fans. Typically, the impeller must 

be made of a conductive, non-sparking material—such as reinforced plastic filled with antistatic agents or an aluminum-manganese 

alloy—and the clearance between the impeller and the volute must be sufficient to prevent mechanical friction. Additionally, 

the motor bearings must use sealed, dust-proof bearings to prevent grease exudates from attracting dust and forming 

combustible deposits.

Furthermore, moving components in refrigeration systems—such as capillary expansion valves and four-way reversing valves—

may generate static charges during switching operations. The entire unit must be equipped with a reliable equipotential 

grounding system, and the grounding resistance must remain consistently below the specified limit. What many users overlook 

is that even if the equipment itself features a spark-proof design, the risk of static electricity buildup still exists if the dedicated 

ground wire is not connected as required during on-site installation, or if the ground wire is oxidized by corrosive media. 

This is precisely the “gray area” that is often overlooked in many safety incident investigations.

IV. The Cascading Consequences of Improper Equipment Selection: From Accident Hazards to 

Severe Environmental Fines

In reality, to cut costs, some companies opt for “generic” dehumidifiers and simply install explosion-proof switches, 

or construct explosion-proof enclosures around standard equipment. These “pseudo-explosion-proof” practices pose 

significant risks. In the event of a fire or explosion, not only will the equipment itself be destroyed, but the incident may 

also ignite residual materials in nearby pipelines, causing the fire to spread. From an environmental perspective, heavy metal 

levels in condensate exceeding standards due to fin corrosion, or volatile organic compound (VOC) emissions caused by 

refrigerant leaks, can trigger online monitoring alarms, leading to administrative penalties such as daily fines and production 

suspensions for rectification. An even more subtle risk lies in the fact that, once the anti-corrosion coating fails, the heat 

exchange efficiency of the dehumidifier continues to decline. To maintain the set humidity level, the compressor must 

operate at high loads for extended periods, leading to a significant increase in energy consumption. Ultimately, 

the initial “savings” actually turn into a massive operational burden.

Conclusion

Industrial dehumidifiers with refrigeration capabilities are by no means “plug-and-play” devices in the chemical and 

pharmaceutical sectors. Their safety and reliability depend on the precise correspondence between the explosion-proof 

rating and the on-site hazardous area, the durable compatibility of the anti-corrosion coating with the process environment, 

and the dual redundancy provided by the spark-free fan design and the unit’s grounding system. When selecting a model, 

users should require suppliers to provide complete explosion-proof certification, anti-corrosion coating test reports, and 

pressure resistance test records, and verify these against simulated temperature, humidity, and corrosive gas concentration 

levels based on actual operating conditions. Only by treating “explosion protection” and “corrosion resistance” as two 

sides of the same coin—mandatory requirements rather than optional features—can dehumidifiers truly serve as guardians 

of safe production rather than sources of risk. When it comes to safety and compliance, any complacency represents the 

most costly drain on a company’s lifeline.