Propane Basics – Understanding Propane Tank Pressure

An image of a propane tank with a gauge displaying pressure.

Table of Contents

Propane gas is arguably among the cleanest energy with extensive applications. 

Thus, having a propane gas tank opens you to limitless energy use- even powering your generator. 

We simply can’t exhaust the propane gas features and upsides because they’re almost endless. It’s the ultimate clean energy solution and is ready for use on any rainy day, no matter where you are. 

Would you like to save money on your propane costs? If so, you’re in the right place! Click here to get 100% free, no obligation quotes from propane dealers in your area.

But there are some propane gas storage basics that you should know to understand how the tank works. 

How is it possible to put gas in a metal container?  There can be only one way- intense pressure. Remember, it’s a gas at room temperature. So it would be so elusive if we stored it in a gaseous state- It’d be impossible to contain. 

So how much pressure is in a propane tank? Rather, what is the exact propane pressure at which a gas that would be a vapor at room temperature changes to liquid? There’s simple science behind this, and we’re here to shed more light on this. 

We’ll explain propane tank pressure ratings and what they mean. Also, you’ll learn why keeping temperatures under check is critical in ensuring your propane gas tank is always in a good state. 

Unlock Propane Tank Pressure: Expert insights on mastering propane basics. Your guide to understanding propane tank pressure.

Why Is Propane Under Pressure?

The open secret to why propane gas is under intense pressure is because this allows it to be easily carried from one point to another. So does that mean it’d be impossible to carry propane in its natural state? 

Pretty much, yeah. Its boiling point is approximately -44 degrees Fahrenheit. Hence, it’d always be in vapor form at temperatures above this. This means propane, a highly vaporous gas, would be impossible to contain unless it was pressurized to a liquid.

The alternative would be lowering propane’s gas temperatures below the boiling point. This would reduce it to liquid form. But maintaining this temperature in general propane household applications would be nearly impossible. 

So the ultimate way to keep the gas in a containable state is by pressurizing it in metallic cylinders. The metal tanks are chosen because they can withstand the external pressure of the propane gas.

What Is The Minimum Pressure of a Propane Tank?

The minimum propane pressure for any tank is 100 psi. Thus, you must compress the gas to a value above this lower limit. But again, there’s a maximum pressure that you should maintain to ensure the gas doesn’t burst off the tank. 

Therefore, we use the range of 100 to 200 psi to define the pressure limits within which the gas should be while in the tank.

At What Pressure Does Propane Turn Into A Liquid?

When defining the ideal propane gas pressure, we must consider the ambient temperatures. Why? Because, like any other gas, propane must obey the classical gas laws. So, in essence, the pressure inside the gas cylinder always changes as per the outside temperatures. 

For example, an average small-sized propane gas tank will have a pressure of 145 psi at 70 degrees. When the outside temperature increases to 100 degrees, the pressure increases to approximately 172 psi. 

Back to our question: what’s the pressure at which propane becomes a liquid? Taking a room temperature of 20 degrees Celsius, you’ll require a pressure of 836 kPA to convert the gas to liquid.

What Would Extremely High Pressure Do to the Propane Gas Tank?

A pressure exceeding 200 psi can be catastrophic as it would be too high for the propane tank to withstand. But manufacturers have a safety precaution to prevent a tank explosion which would happen at such high-pressure levels. 

Any propane gas tank features – alongside other parts – a safety relief valve that opens up when the pressure inside reaches 200 psi. This releases some of the gas outside, thus regulating the internal pressure.

Do propane tanks lose pressure over time?

Yes. As we mentioned earlier, the question of how much pressure is in a propane tank fundamentally depends on the gas laws. Hence, in addition to being temperature dependent, as explained in the previous section, it also depends on the propane gas volume. 

So how do propane tanks lose pressure over time? As you draw the gas from the tank via general household applications such as cooking, its volume reduces. In turn, this translates into a pressure reduction. 

Also, the pressure will decrease if the ambient temperatures are low. As the surrounding heat drops, the gas condenses to liquid form, again reducing its pressure. 

Therefore, in a nutshell,  the two main ways to reduce propane gas pressure include: 

  • Lowering the external temperatures,
  • Using the propane gas(e.g. via cooking/heating) to reduce its volume. 

Safety Considerations

Your propane gas tank is safe for use as long as you don’t store it in extreme temperatures. So what are some key safety precautions to ensure your tank is in good shape and doesn’t pose an explosion risk? 

Find out below.

Extreme Heat

You should be aware of the risk of having your propane gas tank in a high-heat environment. For instance, take a typical case of a garage fire accident or extremely high temperatures. 

This extreme heat will increase the pressure inside the tank leading to a condition called boiling liquid expanding vapor explosion (BLEVE). What actually happens is that the liquid propane inside will vaporize and exert extreme pressure on the cylinder walls. 

If the pressure is too high, the vaporizing gas overwhelms the safety relief valve. With nowhere for the excess pressure to go, the tank will blow up, and this is what causes a gas tank explosion. 

Therefore, extremely high external temperatures are highly dangerous and can cause accidents.

Cold Temperatures

What is the harm of extremely cold temperatures to propane tank pressure rating? Will extremely low temperatures cause an explosion similar to the high temperatures? 

Although there’s no chance of an accident, very low temperatures may significantly reduce the gas pressure, thus hindering its capacity to flow up the pipe. The high pressure inside the tank is typically cardinal in facilitating the gas flow. Hence, it is actually so important. 

But noteworthy, it would be impractical for propane gas to freeze. 

Why? Propane Freezing requires an extremely low temperature (-306 degrees Fahrenheit). However, low temperatures can lead to water vapor formation in the supply pipe. Again this will hamper the gas flow. 

Hence, in cold conditions, it would be helpful to ensure the propane gas tank is in a fairly warm setting for a seamless user experience.

How to check the pressure in your propane tank

Here are the tricks to keep track of your propane psi and ensure you’re operating within the appropriate limits.

Plant a Pressure Gauge

A pressure gauge between the regulator and your tank’s shutoff valve is imperative in monitoring the gas pressure. This device has a scale that shows you when you’re running at the right pressure and when to take mitigating measures to adjust it. 

Such a setup is common in residential systems where pressure monitoring is highly necessary. Failure to keep track means that a problem with the system would affect many people who are reliant on the gas.

Release the Full Pressure to the Gauge

Once you have installed the gauge, allow all the gas pressure to pass via the gauge.

Closing the Valve

Think of a case whereby you suspect your valve is faulty or want to test if there’s a pressure issue in the tank. One of the solutions would be closing the shut-off valve for some while. If you note an increase in pressure, the valve is faulty. 

On the other hand, a reduction in the pressure means that you leak into the system, causing the pressure to decrease.

Tank Pressure Use Tips

We’ve seen how bad high pressure can do to the propane tank. So you’re probably wondering what are some of the ways to keep your tank out of these dangers. Apply the tips below.

Beware of Direct Sunlight

Direct heat will harm your propane gas tank pressure as it can lead to a significant increase that can cause it to blow up. This problem is especially serious when you’ve just refiled the gas tank. 

The pressure is at peak levels at such a time, and direct heat will increase the pressure further. So any direct exposure to direct sunlight (even with propane barbeque grills) can be highly harmful.

Beware Dark-Colored Tanks

If your tank is painted black, you should avoid storing it in areas with direct sunlight at all costs. Why? Black retains heat, unlike bright colors such as white which reflect heat away from their surfaces. 

Hence, a dark-colored tank is likely to explode on exposure to heat compared to a white one.

Store your Tank in a Ventilated Shed

It’s common practice to have your propane tank outside. But primarily, you should ensure that it is under a well-ventilated shed with a roof above to avoid direct sunlight. The garage or underground is a nice place as well.

You may assume that the pressure relief valve will help dissipate the pressure in case it increases as the ambient heat rises. However, sometimes the heat increase can be so high that it actually overwhelms the valve. 

Also, note that the valve works by releasing some of the gas into the atmosphere to relieve pressure. You don’t want to lose your gas this way when you can primarily prevent the issue by storing it in a cool environment. Here are more tips on how to store propane to extend its life.

Avoid Corroded Tanks

Finally, keep off corroded tanks. They’ll cost you big time as if they have a small opening, the tank will lose its pressure, and this will affect functionality. Ensure your tank is always in good shape, and if you identify signs of corrosion or leaks, ask the supplier to replace it. Here’s how to know whether your propane tanks are done.

Summary

Now you are equipped with all the requisite propane gas tank pressure insights to help you understand how the gas flows from inside to the output. If you want to find your area’s top propane gas suppliers, contact Compare Propane

We’ll help you locate the best companies to fulfill your propane needs. That’s all for now. And here’s our parting shot: Take heed of the tips we’ve given you, especially the safety precautions on maintaining gas pressure within the right levels. Adios!

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Ryan McCabe

Ryan McCabe

Ryan is a home and small business energy expert, having overseen retail propane, heating oil, and HVAC services companies. On ComparePropane, Ryan writes about things that people should know when shopping for or using propane in their homes and businesses. 

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