Breathers & Vents.

Whether you are managing a diesel farm tank, bulk lubricant storage in a workshop, or a high-volume flammable fuel installation, tank venting is a critical engineering requirement.

Every time product is pumped out of a tank, displacement air is drawn in. Every time a tank is filled—or ambient heat expands the fluid—air and vapour are forced back out.

Choosing the wrong breather or vent can lead to contaminated fluids, premature pump wear, dangerous vapour accumulation, or even catastrophic tank failure under vacuum pressure.

Here is a breakdown of the five essential types of tank breathers and vents, how they work, and where to deploy them on your site.

1. Filtered Breathers: Clean Air In, Pure Product Out

When non-volatile liquids like diesel, lubricants or adblue are pumped out of a tank, ambient air rushes into the headspace to balance the pressure. If that air is unconditioned, it introduces dust, water vapour, and particulate matter straight into your clean product and the tank itself

Filtered breathers act as the first line of defence. They utilise filter media to strip moisture and fine dirt out of incoming air.

• Best Suited For: Stationary bulk diesel tanks, hydraulic reservoirs, lube oil pods, and oil transfer systems, adblue tanks
• Key Advantage: Keeps fluid clean, prevents particulate wear on downstream pumps, and extends filter life across your machinery.

2. Anti-Splash Filtered Breathers: Preventing Liquid Spills in Motion

In mobile service trucks, fuel pods, fuel tanks, fuel trailers or service trailers liquid sloshes around constantly inside the tank when on the move. Standard filtered breathers can allow liquid product to splash up into the filter element, clogging the media or leaking product onto the exterior of the tank.

Anti-splash filtered breathers incorporate internal baffles, check valves, or splash guards designed to deflect liquid surges back down into the tank while still allowing free airflow during displacement.

• Best Suited For: Mobile service trailers, fuel trailers, service trailers, mobile diesel tanks, construction equipment reservoirs, and field service lube trucks.
• Key Advantage: Eliminates messy oil weeping, prevents filter media saturation, and maintains clean air exchange during transit.

3. Updraft Vents: Directing Vapours Safely Up and Away

Standard free to air, or updraft vents discharge exhausted air horizontally around the perimeter of the tank fitting. When venting diesel or oil storage tanks outdoors, lingering fumes or fine mist near ground level can pose environmental and health hazards for site workers.

Updraft vents (often called high-velocity vents) use a specialised internal nozzle configuration to force exhaust air high into the atmosphere at increased velocity.

• Best Suited For: Aboveground diesel storage tanks, waste oil tanks, and outdoor bulk fuel pods.
• Key Advantage: Directs fumes and vapours safely away from operator work zones, reducing smell and vapor accumulation around the tank base.

4. Pressure Vacuum (P/V) Vents: Essential for Volatile & Flammable Liquids

Storing highly volatile flammable Class 3 liquids like Petrol, Avgas, or Jet A-1 requires a fundamentally different venting approach.

These fuels vapourise aggressively inside the tank's headspace. An open breather would allow expensive fuel to evaporate continuously into thin air while creating a severe fire risk.

Pressure Vacuum (P/V) vents remain tightly sealed during normal ambient storage. They feature spring-loaded or weight-poppet mechanisms that only open when internal pressure or vacuum thresholds are reached:

1. Pressure Relief: When thermal expansion builds internal tank pressure, the pressure valve opens briefly to release trapped vapors.
2. Vacuum Relief: When liquid is pumped out, the vacuum valve opens to pull in fresh air, preventing the tank from collapsing inward under suction.

• Best Suited For: Petrol storage tanks, aviation fuel tanks, and chemical / solvent tanks.
• Key Advantage: Reduces evaporative liquid loss, minimises hazardous site emissions, and assists in meeting AS1940 compliance for dangerous goods storage.

5. Emergency Vents: Safeguarding Against Thermal Disasters

While P/V vents and standard breathers handle normal daily fluid transfer and thermal expansion, they are not designed to cope with extreme pressure spikes caused by external fires.

If an external fire breaks out near a fuel tank, the heat causes stored liquids to boil rapidly, generating massive volumes of vapour in seconds. Without a rapid relief point, the tank will rupture or explode.

An Emergency Vent (or emergency relief hatch) is a secondary safety device mounted on the tank top. It stays shut under standard operation but unseats or lifts under severe pressure to release high volumes of vapour instantly.

• Best Suited For: All aboveground flammable and combustible liquid storage tanks (mandated under Australian Standard AS1940).
• Key Advantage: Prevents catastrophic tank rupture during emergency fire scenarios, saving lives and protecting site infrastructure.

Whenever fluid is pumped out of a tank, a vacuum is created inside the headspace. To balance this pressure differential, ambient air is pulled into the tank.

Conversely, when the tank is refilled or when thermal expansion causes fluid levels to rise, air is forced out.

Without a filtered breather, unfiltered displacement air draws in atmospheric dust, pollens, and water vapour. Over time, these contaminants lead to serious operational issues including:

• Water Contamination: Causes oil emulsification, internal tank rust, and microbial growth in fuels.
• Particulate Pollution: Introduces abrasive dirt particles that accelerate wear on downstream pumps, valves, and equipment.
• Fluid Breakdown: Moisture and dirt speed up oxidation, shortening the usable lifespan of stored oils and chemical products.

Filtered Breathers, from GO Industrial, actively trap microscopic dirt down to sub-micron levels and strip moisture from incoming air before it reaches your product, ensuring liquid purity and protecting the structural integrity of the tank.

Knowing when to replace your tank breather comes down to monitoring visual indicators, system pressure feedback, and environmental exposure.

Modern filtered breathers are equipped with restriction indicators—such as mechanical gauges, differential pressure pop-up buttons, or electronic LED service lights (often found on units like Donaldson T.R.A.P. breathers)—that trigger when particulate accumulation restricts airflow beyond acceptable limits.

Beyond visual alerts, physical signs like noticeable oil weeping around seals, unusual pump cavitation during fluid delivery, or a visible buildup of dirt caked onto the filter housing indicate severe airflow restriction.

As a best practice in demanding industrial, mining, or agricultural environments, breathers should be changed immediately upon an indicator alert or replaced during scheduled preventative maintenance cycles (typically every 6 to 12 months) to avoid pulling excessive vacuum pressure on your storage tank.