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Liquid propane can usually be stored safely for extended periods of time if stored properly. With proper storage conditions, liquid propane can often be stored for 12 months or more before quality begins to deteriorate. However, factors like temperature, tank type, and fill level can impact shelf life. Storing propane tanks outdoors in moderate temperatures and out of direct sunlight can help maximize storage time. Periodically checking tanks for leaks and other signs of deterioration is also recommended regardless of storage time.
What is Liquid Propane?
Liquid propane, also known as LP gas or simply propane, is a flammable gas that is commonly used for heating, cooking, and powering various equipment and appliances. Propane is a hydrocarbon fuel that is derived from natural gas processing and petroleum refining.
Under moderate pressure inside a storage tank or cylinder, propane is compressed into a liquid form. This allows more propane to be stored in a smaller space compared to propane vapor. When the pressure is released, the liquid propane converts back into a gas that can then be used as a fuel source.
Some key facts about liquid propane:
- Propane cylinders are filled with liquid propane under high pressure, typically around 150 psi.
- At atmospheric pressure, propane is a gas, not a liquid.
- One gallon of liquid propane expands into about 270 gallons of propane vapor.
- Liquid propane does not expire or go bad like some other fuels.
- Propane has no smell in its natural state. An odorant called ethyl mercaptan is added for leak detection.
- Compared to other popular fuels, propane has relatively low greenhouse gas emissions.
Knowing the basics of how liquid propane works provides context on how it can be safely and effectively stored long-term. Next, we will look at specific shelf life and storage factors.
How Long Does Liquid Propane Last in Storage?
With proper storage conditions, liquid propane can often last 12 months or longer before quality starts to degrade. However, there are several variables that can impact shelf life:
Storage Temperature
Ambient temperature is one of the biggest factors in liquid propane longevity. Cooler temperatures help slow the oxidation process that can lead to propane breakdown over time. Storing propane tanks in temperate climates between 50-80°F (10-27°C) provides ideal conditions for maximum shelf life.
Avoid storing propane in areas that experience temperature extremes or rapid swings in hot and cold weather. High heat can accelerate propane evaporation and leakage. Freezing temperatures may cause valves and lines to freeze up. Consistent moderate temperatures are best.
Tank Type
The type of propane storage tank or cylinder also impacts shelf life. Small disposable 1 lb. cylinders have the shortest lifespan and can expire in as little as 5-8 years. Refillable 5-20 lb. tanks have a longer 10-12 year lifespan.
Larger ASME tanks holding 30 lbs. and above have the longest storage life, often 15+ years. Their thicker walls and durable construction retain propane better. Check the tank date stamp to determine its age and expected lifespan.
Fill Level
How full the propane tank is will also affect its shelf life. A fully filled tank will last longer than one that is only half full. With less gas volume, there is more room for oxygen to enter the tank and speed up propane deterioration.
Keeping tanks at least 80% full helps maximize storage time. Some recommend flipping tanks upside down occasionally to keep the valve immersed in liquid propane. This prevents any air gaps from forming inside the tank.
Tank Maintenance
Proper maintenance is key to getting the most life out of stored propane tanks. Here are some tips:
- Inspect tanks regularly for dents, rust, leaks and other damage
- Replace outdated or damaged valves
- Repair tanks that show signs of deterioration
- Keep valves tightly sealed with plastic caps when not in use
- Store tanks upright to keep valves immersed in propane
With routine inspections and minor upkeep, propane tanks can safely store gas for years beyond their expected lifespan.
Propane Quality
While liquid propane itself does not expire, its quality can deteriorate over time in storage. Signs of reduced propane quality include:
- Sulfur or rotten egg smell – Odorant is breaking down
- Burning issues – Reduced flame, flaring up
- Valve blockages – Gumming deposits
- Corrosion of tanks/cylinders
If liquid propane displays these issues, it may need to be purged and replaced with fresh propane for optimal performance.
Best Practices for Storing Propane Long-Term
To maximize shelf life, liquid propane should be stored properly. Here are some key best practices:
Location
Store propane tanks outdoors if possible, in a secure, well-ventilated area:
- Outdoors – Prevents gas accumulation indoors and allows for air circulation
- Well-ventilated – Avoid enclosed spaces like sheds or garages
- Secure – Keep area locked or fenced off to avoid tampering
Avoid direct sunlight exposure which can overheat tanks.north-facing spaces or shaded areas are ideal.
Positioning
Store propane tanks upright and on a flat, sturdy surface:
- Upright – Keeps valves immersed in liquid propane
- Flat surface – Prevents falling over or damage from ground debris
- Sturdy base – Supports heavy weight without shifting
Do not stack tanks vertically. Laying tanks horizontally is also not recommended.
Temperature
Maintain moderate temperatures if possible:
- 50°-80°F ideal – Slows propane evaporation
- Avoid extremes – Freezing causes blockages, high heat accelerates decay
Consider storing in above-ground shelters with ventilation if needed to maintain stable temps. Monitor with a thermometer.
Fill Level
Keep tanks at least 80% full:
- Minimizes air space where oxidation occurs
- Rotate stock – Use older propane first
- Consider fill incentives – Some suppliers offer discounts for topping off
Avoid completely emptying tanks if the gas will not be used right away.
Maintenance
Routinely inspect and maintain tanks:
- Monthly inspections – Check for leaks, corrosion, dents, debris
- Annual deep inspections – Thoroughly assess entire tank
- Keep valves sealed – Use plastic caps when not in use
- Replace outdated parts – Valves, hoses, gauges, etc.
Well-maintained tanks last longer than neglected tanks. Keep records of inspection dates and work performed.
Following these best practices will help liquid propane retain its quality and shelf life for years to come.
Signs Your Propane May Need Replacing
While liquid propane can technically be stored indefinitely, its quality and performance will eventually decline. Monitor your propane tanks for any of these warning signs that the gas may need replacing:
- Sulfur/rotten egg scent – Ethyl mercaptan odorant breaking down
- Changes in burning – Fluctuating flames, excess smoke
- Equipment issues – Clogged parts, improper combustion
- Tank corrosion – Rust, dents, leaks around valves
- Valve problems – Gummed up and not functioning properly
- Difficulty starting – Equipment won’t ignite or starts then stops
The odorant in propane provides the strongest indicator that it may be expired. While pure propane has no smell, you should clearly detect the “rotten egg” scent added to alert of leaks.
If the intensity of this smell has diminished or changed, the propane is deteriorating. Any other performance issues could signal impurities in the gas.
Test the propane in a safe environment away from combustibles if uncertain. It is also a good idea to periodically purge and replace old propane as routine maintenance.
Safely Replacing Expired Propane Tanks
When liquid propane has reached the end of its shelf life, tanks should be properly purged and replaced with new, fresh propane. Here is how to safely swap outdated propane:
Use up Remaining Gas
The simplest option is to continue using the propane until empty for items like gas grills, camp stoves, or construction equipment. This avoids waste and risks of purging tanks.
Just be aware that performance may decline as the remaining gas quality degrades.
Purge Tanks
Once tanks are empty or contain only unusable propane, they need to be purged of all remaining gas:
- Remove tank valves completely
- Position tank upside down to drain
- Ventilate tank outdoors for 48-72 hours
- Verify tank is purged by spraying water – no bubbles should form
Never attempt to vent flammable gases inside. Tanks must ventilate thoroughly outside only.
Replace Propane
With storage tanks properly purged of old gas, they can now be refilled with fresh propane:
- Inspect tank interiors and valves for any damage
- Repair/replace tanks or valves as needed
- Reinstall valves tightly
- Have certified propane supplier refill tank
- Leak test new propane and valves before use
Check with your propane supplier for any tank testing or recertification required before refilling purged tanks. Always handle propane tanks and gas with caution.
Disposing of Expired Propane Tanks
If liquid propane tanks have reached the end of their lifespan and can no longer be refilled, they must be disposed of properly. Here are safe disposal tips:
Empty Tank Completely
Never dispose of tanks that still contain propane! All remaining gas must be used up or properly purged as outlined above.
Attempting to dispose of tanks with flammable vapors still present creates serious risks of fire and explosion. Confirm tanks are fully emptied first.
Render Tank Unusable
Once empty, tanks should be punctured or otherwise rendered unusable:
- Punch holes to prevent re-use
- Cut or rupture tank bodies
- Remove valves completely
This prevents expired tanks from being unlawfully refilled with old or impure propane.
Recycle Tanks
Most empty and unusable propane tanks can be recycled:
- Contact local solid waste authority to find recycling options
- Some retailers and propane suppliers also accept old tanks for recycling
- Recycling recovers metal components for reuse
Proper documentation may be required verifying tanks are completely empty and unfit for reuse before recycling facilities will accept them.
Dispose as Hazardous Waste
If no recycling options are available, rendered propane tanks may be disposed through hazardous waste collection programs. Contact your local waste management authority for disposal instructions.
Never place potentially hazardous empty tanks with normal trash. Follow all laws and regulations when disposing of propane cylinders.
Key Takeaways on Storing Liquid Propane
To summarize key points on maximizing liquid propane storage life:
- With proper storage, liquid propane can often last 12+ months before quality decline
- Ideal storage conditions – moderate temps, 80%+ full tanks, upright position
- Inspect tanks regularly and perform maintenance to extend lifespan
- Monitor for changes in smell or performance that signal expired gas
- Completely purge tanks of old propane before refilling
- Safely recycle or dispose of outdated cylinders
Being an informed consumer helps ensure liquid propane can be stored safely and cost-effectively for the long term. Always follow manufacturer and safety guidelines when handling propane tanks and fuel. With ideal storage and maintenance, liquid propane can effectively power homes and businesses for many years to come.
Frequently Asked Questions
Does propane go bad?
Propane itself does not expire or go bad like some other fuels. However, the quality and performance of stored liquid propane will gradually deteriorate over time. Signs of bad propane include changes in smell, difficulty igniting appliances, altered burning properties, and tank corrosion.
Should propane tanks be stored indoors or outdoors?
Outdoor storage is recommended whenever possible for safety and ventilation. Storing propane indoors risks gas buildup and explosion. Outdoors minimizes these hazards while allowing air circulation to help maintain gas quality. If tanks must be kept indoors, ensure the area is well-ventilated.
How should you dispose of an old propane tank?
Empty the tank completely, render it unusable by puncturing holes, and recycle if possible. Facilities that accept recycled scrap metal may take depleted propane tanks if properly emptied and documented as non-hazardous. If no recycling options are available, contact hazardous waste management authorities to dispose of the tank safely.
Can you lay propane tanks on their side?
It is not recommended to store propane tanks horizontally. They should be kept upright to keep the valve immersed in liquid propane which reduces oxidation. Laying tanks on their side risks valve damage and air pockets forming inside the tank which can accelerate propane deterioration.
Is it safe to use old propane?
Use caution when burning aged propane, especially if signs of deterioration like smell or performance changes are detected. While not necessarily unsafe, very old propane may not burn as cleanly, completely, or efficiently as fresh propane. Purging and replacing outdated gas is advised for optimal operation of propane appliances and equipment.
Conclusion
Liquid propane has an indefinite shelf life if stored properly, with expected retention of quality and performance for 12+ months in ideal conditions. Following best practices for propane storage, regularly inspecting tanks, and timely replacement of expired gas allows liquid propane to be a safe, reliable fuel source for the long term. With proper handling, this versatile gas can continue powering residential, commercial, agricultural and industrial applications well into the future.
