Pressure compensating plugs: role and limitations

Pressure compensator plugs: what are we talking about?

In the trade we find pressure compensating plugs, also called pressure balancing plugs.
They are mainly used in waterproof enclosures, such as electrical boxes, electronic boxes or connection boxes, in order to limit the effects of temperature-related pressure variations.

👉 [Explanatory video insertion of the cork]

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What is a pressure compensating plug?

A pressure compensating plug is a connector fixed directly into the wall of a watertight housing.

It is composed of a microporous membrane Who:

• allows air (and therefore water vapor) to pass through,
  
  
• blocks the passage of liquid water (rain, projections, runoff).
  
  

These devices are commonly used in waterproof electrical boxes, inside and out.

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How does a pressure compensating plug work?

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When the temperature rises

• The air inside the case heats up.
  
• Her pressure is increasing.
  
• Thanks to the plug, air can escape through the membrane.
  
• Internal and external pressures are in balance.
  
  

When the temperature decreases

• Internal pressure is falling.
  
• The outside air enters the housing via the membrane.
  
• Again, the pressures are equal.
  
• Liquid water does not penetrate, thanks to the hydrophobic membrane.
  
  

👉 The cork therefore acts like a passive pressure control valve.

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What are pressure compensator plugs really for?

Without a cap, the repeated pressure variations in a waterproof electrical box can:

• excessively stress the joints,
  
• accelerate their aging,
  
• cause a long-term loss of tightness.
  
  

👉 The main function of pressure compensating plugs is therefore to preserve the mechanical tightness of the boxes., preventing liquid water from penetrating due to damage to the joints.

They are particularly used in:

• outdoor electrical boxes,
  
• waterproof connection boxes,
  
• boxes exposed to strong temperature variations.
  
  

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Pressure and condensation compensating plugs: pay attention to preconceived ideas

Can they eliminate condensation in a case?

👉 The answer is no.

Pressure compensating plugs do not prevent water vapor from entering in a case, since the membrane allows air to pass through... and therefore moisture in the form of vapor.

Why does condensation appear despite the cork?

When the outside temperature drops rapidly:

• the water vapor present in the air in the housing,
  
• Reaches its dew point
  
• and condense on the inner walls.
  
  

Result:

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➡️ condensation in the electrical box,
➡️ water droplets,
➡️ risks of corrosion and malfunction.

The cap protects against external liquid water, but not against internal humidity.

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How do you avoid condensation in a waterproof case?

To treat condensation, you must act on the water vapor present inside of the case.

AS-B tape: a complementary solution to compensating plugs

The product AS-B was designed to address precisely this problem. It works by adsorption of water vapor contained in the case, which allows you to:

• reduce the internal ambient humidity,
  
• avoid reaching the dew point
  
• Prevent the Condensation formation.
  
  

Unlike compensating plugs:

• AS-B acts directly on the humidity,
  
• operates without electricity,
  
• does not saturate permanently,
  
• does not require any maintenance.
  
  

👉 Discover the AS-B product

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Results validated in the laboratory

Our laboratory tests show that:

• Pressure compensating plugs are not enough to avoid condensation,
  
  
• Only the use of an adsorbent such as AS-B makes it possible to maintain a dry environment inside the waterproof cases.
  
  

👉 Read the full article : How to prevent condensation in electrical boxes

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Conclusion

Les pressure compensating plugs are essential to maintain the mechanical tightness of the cases in the face of temperature variations. On the other hand, they do not treat internal condensation, which is still one of the main causes of corrosion and breakdowns.

👉 For complete protection of a waterproof electrical box, the combination: pressure compensator cap + AS-B is a coherent, sustainable and effective approach.