Getting Your Tank Ready for the Long Haul
Properly preparing your scuba tank for long-term storage is a critical safety and maintenance procedure. It’s all about preventing internal corrosion, which can permanently damage the tank and compromise its structural integrity. The core principle is simple: store the tank with a small amount of clean, dry, compressed air inside, never empty. An empty tank can “breathe,” allowing humid air to enter, which leads to rust. By following a detailed, step-by-step process, you ensure your tank remains in pristine condition, ready for its next adventure.
The Golden Rule: Never Store an Empty Tank
This is the single most important rule in tank storage. When a tank is completely empty, even with the valve closed, changes in ambient temperature and pressure can cause it to draw in moist atmospheric air. This moisture is the primary enemy of your tank’s interior. Over months or years, this leads to rust, pitting, and ultimately, a failed hydrostatic test. The goal is to create a stable, dry environment inside the tank. A positive pressure of around 200 psi (approximately 14 bar) is the industry-standard recommendation. This low pressure is sufficient to prevent outside air from entering while being low enough to be completely safe.
Step-by-Step Preparation Guide
Before you even think about storage, a thorough post-dive preparation is essential. Here’s a detailed breakdown:
1. The Final Dive Rinse: After your last dive, give your tank a thorough external rinse with fresh water. Pay special attention to the valve area, where salt, sand, and other debris can accumulate. Avoid high-pressure sprays directly on the valve to prevent forcing water past the O-ring.
2. Internal Flushing (The Controversial Step): Opinions vary on this. Some divers advocate for a quick internal flush with a small amount of fresh water to remove any saltwater mist. If you choose to do this, it must be done correctly to be safe. The tank must be nearly empty (less than 50 psi). Attach a regulator to the tank, open the valve slightly, and have a partner slowly pour a cup or two of fresh water into the valve orifice for a few seconds. Immediately close the valve. The key is to use a minimal amount of water. The safer, more recommended method is to rely on proper draining after each dive and maintaining a dry air supply.
3. Draining and Drying: This is non-negotiable. After rinsing, drain all water from the tank. Loosen the tank band or remove it from the BCD and stand it upright in a cool, dry place. Leave the valve slightly open to allow any residual moisture to evaporate. Let it dry for at least 24 hours. You can also gently press the valve core with a tool to release a burst of air, which helps eject any water droplets—do this only when the tank pressure is very low.
4. The Final Inspection: Once dry, perform a visual inspection. Check the exterior for any new dings or scratches that might need addressing. Look at the valve for signs of corrosion or damage.
5. Setting for Storage: Now, you have two options based on your tank’s current pressure:
- If the tank has more than 200 psi: You can leave it as is. Do not intentionally vent air down to 200 psi, as you risk introducing moisture during the process.
- If the tank is nearly empty: You need to have it filled. Explain to the dive shop that it’s for long-term storage, and request a fill from a clean, dry air source. Ask them to fill it to only 200 psi. A responsible fill station will understand.
6. Valve Protection: Screw the plastic valve cover on snugly. Do not overtighten it, as this can crack the cover or damage the valve threads. The cover keeps dust and bugs out.
Choosing the Perfect Storage Location
Where you store the tank is almost as important as how you prepare it. The ideal location has the following characteristics:
| Factor | Ideal Condition | Why It Matters |
|---|---|---|
| Temperature | Cool and Stable (e.g., 50-70°F / 10-21°C) | Prevents pressure fluctuations that could stress the metal and cause “breathing.” Avoid garages or sheds where temperatures swing wildly. |
| Humidity | Low and Dry | Directly prevents condensation and corrosion inside and out. A basement with a dehumidifier is better than a damp garage. |
| Sunlight | Complete Darkness | UV radiation degrades the tank’s epoxy liner (if present) and can fade the paint and labels. |
| Position | Upright and Secure | Prevents the tank from being knocked over, which could damage the valve. Using a tank stand or placing it in a corner is ideal. |
| Chemicals | Away from fumes (paint, fuel, cleaners) | Chemical fumes can accelerate corrosion and potentially contaminate the air supply. |
A Note on Lying Down: While storing upright is best, lying a tank on its side on a soft surface (like a carpet) is acceptable for short periods. For long-term storage, upright is strongly recommended to ensure any microscopic moisture collects at the bottom, away from the valve.
Common Mistakes That Can Ruin Your Tank
Even experienced divers can slip up. Be sure to avoid these critical errors:
Mistake 1: The “Empty and Forget” Method. Storing a tank with zero pressure is the fastest way to guarantee internal corrosion. It’s like leaving a steel pipe open to the elements for years.
Mistake 2: Over-tightening the Valve Cap. This seems like a good idea for a “tight seal,” but it can crack the plastic cap or, worse, damage the brass valve stem. Snug is enough.
Mistake 3: Storing with a Regulator Attached. Never do this. The constant pressure on the regulator’s first stage O-ring can cause it to take a “set,” leading to a leak later. It also puts stress on the valve stem.
Mistake 4: Neglecting Visual Inspections. Even in storage, give your tank a quick look every few months. Check for any signs of external rust, especially under the boot if it has one.
The Role of Professional Maintenance
Your preparation for storage is just one part of the tank’s lifecycle. Professional oversight is mandatory for safety. There are two key services:
Visual Inspection (VIP): This should be performed annually. A certified technician will inspect the tank’s interior and exterior for corrosion, damage, and valve integrity. They will also check the tank’s hydrostatic test date.
Hydrostatic Test: This is a strength test required every 5 years in most countries (3 years in Canada, for example). The tank is pressurized with water to a level far beyond its working pressure to ensure the metal has not permanently expanded or weakened. A tank that fails is condemned and must be taken out of service.
Before storing your tank for a long period, it’s a smart practice to check when these next services are due. It’s better to get a VIP done before storage than to discover an issue years later.
Gearing Up for Your Next Dive
When you’re ready to dive again, don’t just grab your tank and go. Proper reactivation is key. Unscrew the valve cap and inspect the valve orifice for any debris. Have the tank visually inspected and filled at a reputable shop. Before your first dive back, always perform a pre-dive safety check, tasting the air from the regulator for any unusual odors. Taking these steps ensures that your well-preserved scuba diving tank will perform safely and reliably, just like the gear designed for confident and passionate ocean exploration. The commitment to safety through innovation means using equipment that you can trust, from the design phase to your preparation rituals, ensuring every dive is a joy.