Air Sentry | Guardian - Small (9") | BEST - Desiccant Breather With Valves

GUARDIAN® Series Desiccant Breathers — Highest Level Contamination Control 

The GUARDIAN® is Air Sentry's industry-leading desiccant breather series — and for good reason. Whether you're protecting a hydraulic reservoir, a gearbox, a diesel tank, or an oil drum, the Guardian Series delivers a level of contamination control that old-school mesh filters and old technology dessicant breathers simply cannot match.

Think about it: every drum, every reservoir, every piece of equipment that isn't sealed is constantly breathing. Even stored indoors, the most dangerous particles are the microscopic ones you can't see — and the humidity that silently converts to water inside your oil. Leaving any drum or reservoir without a desiccant breather isn't just risky, it's a slow-motion equipment failure waiting to happen.

This Product Page is for the Guardian Small — 9″ H × 5.125″ D

The Guardian Small or known as the G5, is the go-to choice for tight installation spaces, small gearboxes, and smaller hydraulic reservoirs where a full-size breather won't fit or isn't needed. Same Guardian protection, same Tritan® housing, same 2-micron dual filtration — in a compact footprint.

• Silica Gel: 1.5 lbs
• Max Adsorption Capacity: 9.2 fl oz
• Max Air Flow: 25 CFM
• Max Reservoir Fluid Flow: 187 GPM
• Dimensions: 9″ H × 5.125″ D

Need more desiccant capacity for larger reservoirs or higher-demand environments? See the Guardian Medium (12″) and Guardian Large (16″) — available as separate listings.

Size Comparison — Find the Right Guardian for Your Application

All Guardian models share the same 5.125″ diameter, 25 CFM air flow, and 187 GPM reservoir fluid flow. The difference is desiccant capacity — which determines how long the breather lasts between cartridge changes. When in doubt, size up.

Size	Height	Silica Gel	Max Adsorption	Best For
Small ★ (This Product)	9″	1.5 lbs	9.2 fl oz	Tight spaces, small gearboxes, small reservoirs
Medium	12″	2.8 lbs	17.2 fl oz	Mid-size hydraulic systems, diesel tanks, mobile equipment
Large	16″	4.5 lbs	27.6 fl oz	Large reservoirs, high-cycle equipment, extended service intervals

Why the Guardian Series?

• Tritan® casing — Patented material with exceptional impact and chemical resistance across a wide operating temperature range: -20°F (-29°C) to +200°F (+93°C)
• Dual 2-micron filters — One on the inlet, one on the outlet, on every model
• Visual desiccant indicator — Gold/yellow when fresh, dark green when depleted — no guesswork, no service logs required
• Modular, stackable design — Customize each unit with add-ons: wash-down cap, compound indicating gauge, high-capacity HEPA filter, pressure valve, and more
• Longer breather life, longer equipment life — The Guardian’s design reduces desiccant waste and extends service intervals

How the Guardian Breathes — And Why It Matters

The Guardian is engineered around a precise two-stage valve system that mirrors how your equipment actually breathes:

• Top Breather Valves (×4) — Located at the top of the unit, these are breather valves (not check valves). They open only when the equipment inhales — drawing air in through the desiccant and 2-micron filter media, removing moisture and particles before they ever reach your fluid.
• Bottom Exhale Valves (×4) — Four exhale valves at the base of the unit open when the equipment exhales, allowing air to escape freely without passing back through the desiccant — preserving desiccant life and maintaining proper pressure balance.

Optional Add-Ons: Isolation Check Valve & Pressure Valve

Isolation Check Valve (Optional)

An additional protection layer designed for high-exhalation applications. When equipment exhales rapidly — as in diesel tanks, high-capacity hydraulic systems with fast-moving fluid (e.g., hydraulic presses), or mobile equipment where splashing is a risk — the check valve protects the breather from backflow and fluid contamination, shielding the desiccant from premature saturation.

The isolation check valve is also recommended when stacking two Guardian units, as the combined exhalation force increases the risk of backflow through the breather valves.

Pressure Valve / HEPA Filter (Optional)

In environments with extremely high particle contamination — cement plants, grain handling facilities, mining operations, and similar dusty or particulate-heavy settings — a pressure valve is strongly recommended.

Here’s why: in these conditions, airborne particles can clog the inlet filter before the silica desiccant is fully depleted. When that happens, the breather stops flowing air — but the silica still looks like it has capacity remaining. The result is a false indication: the desiccant color hasn’t changed, but the breather is no longer protecting your equipment. The pressure valve detects this restriction, and if possible adding a HEPA filter will provide an additional barrier to dramatically extend service life in high-contamination environments.

The Silica Desiccant — Your Visual Service Indicator

The heart of the Guardian is its silica gel desiccant — and one of its most practical features is that it tells you exactly when it’s time for a change, no guesswork required.

• Gold / Yellow — Fresh, fully active desiccant. Full moisture-absorbing capacity. Your breather is working at 100%.
• Light Green — The silica has begun absorbing moisture. Capacity is being used, but the breather is still performing well. Monitor it.
• Dark Green — The silica is saturated. Moisture-absorbing capacity is depleted. Time to replace the cartridge.

This color-change system makes service intervals simple and reliable — no need to track hours or guess. When it’s dark green, change it. The Tritan® housing is transparent precisely so you can check the desiccant status at a glance, from a distance, without removing the breather.

Important note: In high-particle environments, the inlet filter can become clogged before the silica changes color. If airflow seems restricted but the desiccant still looks gold or light green, inspect the inlet filter and consider adding a HEPA filter and a pressure valve to your setup.

Primary Applications

• Most Small hydraulic systems
• Small & Medium industrial gearboxes
• Mobile equipment with hydraulic systems — garbage trucks, service trucks, flatbeds, mining equipment, and construction machinery
  
• Small Diesel tanks installed on Diesel Generators (Best Insurance to keep Diesel tanks Cleand and Dry for longer.

Ideal for Equipment That Doesn’t Run 24/7

This is where the Guardian truly separates itself from the competition. The breather valves open only on demand — meaning your desiccant isn’t being depleted while the machine sits idle. For construction equipment, garbage trucks, mining machinery, agricultural equipment, and any fleet that cycles on and off, this is the single most important feature you can have in a breather. Your desiccant lasts longer. Your oil stays cleaner. Your equipment lasts longer.

Compare that to a mesh filter: it offers zero moisture protection, zero particle filtration at the micron level, and zero isolation when the machine is off. The Guardian isn’t an upgrade — it’s a completely different category of protection.

Outstanding for Filter Tanks & Hydraulic Reservoirs

Diesel tanks are often overlooked when it comes to contamination control — but they breathe just like everything else. Install a Guardian and watch your filter life and fluid cleanliness numbers improve. Customers who make the switch consistently report extended equipment life and fewer unplanned maintenance events.

The Best Protection for Oil Drums

Every oil drum breathes — constantly. Temperature swings cause drums to inhale and exhale air, pulling in airborne particles and moisture with every cycle. Even stored under a roof, the invisible micro-particles and humidity are the real threat. Water in oil is one of the leading causes of premature bearing and component failure. The Guardian Series is the definitive solution: snap one on any drum and eliminate that risk entirely.

The Only Air Sentry Breather Recommended for Diesel Fuel Applications

The Guardian Series is the only desiccant breather Air Sentry recommends for diesel fuel applications — and it must be paired with an isolation check valve. Look for models ending in NC, NG, or NGC. Not available in models ending in N. Not recommended for other fuel applications.

The Most Economical Desiccant Breather on the Market

The Guardian pays for itself by extending the life of the equipment where it is installed. Plus, its modular design allows you to configure it multiple ways — adapting to your environment, your application, and your service requirements without replacing the entire unit.

• Demand-only breather valves protect your desiccant — By opening only when the equipment inhales, the breather valves prevent unnecessary desiccant saturation. You’re not burning through desiccant capacity while the machine sits in the yard overnight or over the weekend.
• Replaceable cartridges — When it’s time to service the breather, you replace only the desiccant cartridge — not the entire unit. The Tritan® housing keeps going, and your cost per service drops significantly.
• Lower cost per pound of desiccant — Guardian cartridges deliver more desiccant capacity per dollar compared to single-use throw-away breathers. Over the life of your equipment, the savings add up fast.

It’s not the cheapest breather on the shelf. It’s the cheapest breather to own.

Guardian Accessories — Build the Right Setup for Your Environment

The Guardian’s modular design means you’re never locked into a one-size-fits-all solution. The right accessories can dramatically extend service life, protect against specific environmental hazards, and keep your breather performing at its best. Here’s what’s available — and when you need it:

Shield Wash-Down Cap (Optional)

Protects the breather from direct water spray during equipment wash-downs and from dust accumulation in dirty environments. The Shield Cap keeps the breather valves clear and functional even in the harshest conditions.

Recommended for: Food processing facilities, mining operations, cement plants, pulp and paper mills, outdoor equipment, and any application where high-pressure wash-down is routine.

High Capacity Air Filter — 0.3 Micron HEPA (Optional)

An additional pre-filter that captures ultra-fine particles at 0.3 microns before they reach the desiccant element. In extremely dusty or dirty environments, particles can clog the standard inlet filter before the silica is depleted — causing a false service indication and leaving your equipment unprotected. The HEPA filter adds a critical extra barrier, dramatically extending the service life of the desiccant cartridge.

Recommended for: Cement plants, grain handling, mining, construction, and any high-contamination environment. Requires the Modular Stack Ring for installation.

Modular Stackable Ring (Optional)

The foundation of the Guardian’s modular system. The Stack Ring connects additional filter cartridges — including the HEPA Air Filter — directly to the breather body, extending capacity and protection without replacing the base unit.

Recommended for: Any application where the HEPA filter or additional desiccant capacity is needed. Required for HEPA filter installation.

Not sure which accessories are right for your application? Contact us at DRIVEN Racing and we’ll help you build the ideal Guardian setup — no guesswork required.

Frequently Asked Questions

What is a desiccant breather and why do I need one?

A desiccant breather is a filtration device that replaces the standard vent cap on reservoirs, gearboxes, drums, and other fluid-containing equipment. As equipment breathes — expanding and contracting with temperature changes — air is drawn in and pushed out. Without a desiccant breather, that air carries moisture and particles directly into your fluid. The Guardian Series filters that air down to 2 microns and absorbs moisture before it ever reaches your oil, dramatically extending fluid and equipment life.

How do the breather valves and exhale valves work?

The top breather valves open only when the equipment inhales, pulling air through the desiccant and filter media. The four exhale valves at the bottom open when the equipment exhales, releasing air without depleting the desiccant. This one-way flow design is what makes the Guardian so efficient — desiccant is only used when it needs to be.

How do I know when to change the desiccant cartridge?

Watch the color. Fresh silica is gold or yellow. As it absorbs moisture, it transitions to light green, then dark green — which means the silica is fully saturated and the cartridge needs to be replaced. The transparent Tritan® housing lets you check the status at a glance without removing the breather. In high-particle environments, also check for inlet filter clogging, which can restrict airflow before the silica is fully depleted.

Is the Small (9″) the right size for my application?

The Small Guardian is ideal for tight installation spaces, small gearboxes, and smaller hydraulic reservoirs. With 1.5 lbs of silica and 9.2 fl oz of adsorption capacity, it’s best suited for lower-volume systems in moderate environments. If you have a larger reservoir, higher breathing rate, or a more demanding environment, consider the Guardian Medium (12″) or Guardian Large (16″) for longer service intervals and greater capacity.

When do I need the isolation check valve?

The isolation check valve is recommended for: diesel tanks and high-capacity hydraulic systems with rapid fluid movement (e.g., hydraulic presses); mobile equipment where splashing is a risk; and applications where two Guardian units are stacked.

When do I need a pressure valve or HEPA filter?

In high-particle environments — cement plants, grain facilities, mining, and similar settings — particles can clog the inlet filter before the silica is depleted, causing a false indication (the desiccant still looks good, but the breather isn’t flowing). A pressure valve detects this restriction. A HEPA filter adds an extra barrier to extend service life. Both are strongly recommended in these conditions.

Why is it so important to put a desiccant breather on oil drums?

Oil drums breathe constantly — every temperature swing pulls outside air in. Even indoors, the real threat is the microscopic particles and humidity you can’t see. That moisture turns to water in your oil, accelerating oxidation, promoting microbial growth, and destroying lubrication film. A drum without a desiccant breather is a contamination event in slow motion. The Guardian stops it cold.

Is the Guardian Series better than a standard mesh breather vent?

It’s not even a fair comparison. Mesh vents offer no moisture protection and no micron-level particle filtration. They’re open to the atmosphere 100% of the time — including when equipment is idle. The Guardian filters to 2 microns, absorbs moisture with silica gel desiccant, and its breather valves open only on demand. The result is cleaner fluid, longer component life, and lower total maintenance cost.

Can I replace just the desiccant cartridge, or do I have to buy a whole new breather?

You replace only the cartridge. The Tritan® housing is built to last and stays on the equipment. This is a major cost advantage over single-use breathers — you’re paying for desiccant capacity, not a new housing every time.

Can the Guardian Series be used on diesel fuel tanks?

Yes — it is the only Air Sentry desiccant breather recommended for diesel fuel applications. However, it must be used with an isolation check valve. Look for Guardian models ending in NC, NG, or NGC. Models ending in N are not suitable for diesel applications. The Guardian is not recommended for gasoline or other fuel types.

What’s the operating temperature range?

The Guardian Series operates from -20°F (-29°C) to +200°F (+93°C), making it suitable for extreme cold-weather storage as well as high-temperature industrial environments.

Do I need any accessories with my Guardian?

It depends on your environment. For most standard hydraulic and diesel tank applications, the base Guardian is all you need. For dusty or wash-down environments, add the Shield Wash-Down Cap. For extremely high-particle settings like cement plants or grain facilities, add the HEPA Air Filter and Modular Stack Ring. Not sure? Contact us and we’ll spec the right setup for you.