how do pressure cookers work

How Do Pressure Cookers Work [2022] – Can They Explode?

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If you are looking for how does pressure cooker work and want to know everything about how do pressure cookers work, then this article is the one for you. Not only that you will also find all the answers for questions such as, “Who invented pressure cookers?”, “Will pressure cooker explode?”, and “What happens when you are cooking at high altitudes?”

If you are someone who has never used the pressure cooker, the moment they here the word pressure cooker, all they can think in their mind is nothing but a danger. It’s really unsafe to use the pressure cooker as there are high chances of it to get explode.

Not only that, they will think of all kinds of wrong things that could happen including, its lids getting flied off, huge explosions, or even more worse than that. Its not funny though, as the one’s who had used or using the pressure cooker, may sometimes think of the same.

Well, it was also true to some extent in the past. But today they are just fictional in the movies. In short, the pressure cookers that are available in the market are so well designed, they are totally safe to use. In fact, today they are one of the best and most useful kitchen appliance in the kitchen that solves all of your cooking problems and helps to cook delicious food. 

A pressure cooker is your day-to-day cooking utensil that helps to cook food in no time. If you are thinking buying a pressure cooker, read this article, it will help you choose the best pressure cooker in the market.

The journey of pressure cookers was all started in the late 17th century, when a french physicist and mathematician named Denis Papin made an invention called as “steam digester”, which he shared his notes with Christiaan Huygens, Gottfried Leibniz, and Robert Boyle on the same. You can tell that the “steam digester” is the precursor to the pressure cooker as well as steam engine, as both works on the same principle.

People called the “steam digester” also by the names of “Papin’s digester” or “bone digester”, as it was designed to extract fats and collagen from bones. Once they are extracted, the rendered bones can be grounded into bone meal which then can later be used as a dietary supplement or fertilizer.

how do pressure cookers work

Similar to today’s pressure cooker, the steam digester was designed with a closed pot which was tightened with a tight-fitting lid. Once the food and water starts to get heated up, the steam used to get trapped inside the vessel, which used to rise the pot’s internal pressure. 

However, in Papin’s design there was one failure, which is non-inclusion of pressure-release mechanism. This lead to many explosions of the product at the early stages due to trapped high intense pressure created by steam. These failures lead to the invention of steam-release valve by Papin to prevent causing accidents and made the steam digester safe for use.

It’s been 200+ years now, the design got redefined by many in different concepts for usage. But it was 1930s, the introduction of Alfred Vischer’s “Flex-Seal Speed Cooker” is the actual pressure cooker which was firstly brought into home kitchen. 

And from then, the National Pressure Cooker Company brought the best pressure cooker model in 1939 to the market. Now, if you see in the market, there are plenty of pressure cooker manufacturing companies which includes the well known Hawkins, Prestige, and so on.

From then, now the different company’s have designed pressure cookers in many ways, but the fundamentals of pressure cooker working remains the same. The old pressure cookers use to have a weighted jiggler valve which used to release pressure and regulates pressure, by making a rattling noise as the steam starts to escape. 

In the 18-19th century, all pressure cookers works the same way, but they have a pressure-sensitive locking mechanisms and a pressure release valve as a safety mechanism, but were still too noisy. These pressure cookers are called as first-generation pressure cookers.

When the generation moved further, we found second-generation pressure cookers which were more quieter than that of first-generation pressure cookers. The second-generation pressure cookers have a hidden spring-loaded valve and allows you to choose two different pressure settings by the adjustment of a dial. Some of the pressure cookers in this range won’t release any steam while cooking, instead they have a pressure indicator level that indicates pressure level.

The third-generation pressure cookers are the new models and latest innovation which we see in the 21st century, which are designed with an electric heat source that helps to maintain precise pressure while cooking. They are simple to use and come with timer for cooking. Also, they have digital controllers, which offer many options for cooking such as, delayed cooking, smart programming for cooking certain kind of foods.

Will Pressure Cooker Explode?

Now you know the history of pressure cooker, let us come to the most valuable question of all time, will the pressure cooker explode? The straight forward answer to it is, the  today’s pressure cookers will never explode when you use them safely and as per user manual which comes along with the pressure cooker when you buy.

Yes, the explosion of pressure cookers was really true, but it was way back in the 17th century when it was just invented and had no safety mechanism to handle the pressure generated and trapped inside the vessel pot. 

Today’s pressure cookers are highly safe while cooking. Thanks to the rigorous innovations and improved design, which many pressure cooker companies now have adopted. 

history of pressure cookers

After the World War II, the demand for pressure cooker was all time high as the steel was allocated for the production of pressure canners. Many pressure cooker manufacturers started the production of pressure cookers for fulfilling the demand while using the expensive materials. 

But the models that are manufactured in the late 1950s had a single, poorly constructed weighted valve that easily clogged with debris. The moment when the pressure was built to an extreme level, either the gasket would blow up or the water or steam would spill from the top, where in sometimes the lid used to fly right off.

Now we have come so far in the journey of pressure cookers, where in the pressure cooker manufacturers have brought in great innovations in design and manufacture which makes the pressure cookers completely safe to use. 

Many pressure cookers now a days have multiple safety mechanisms such as multiple valves so called safety valves, dual pressure regulators, and spring-loaded lid locks. This means, the pressure cookers are totally safe to use.

How Do Pressure Cookers Works?

Before we jump on to, how pressure cookers work, let us first understand what is a pressure cooker?

What is a Pressure Cooker?

A pressure cooker is a cooking utensil which is used to cook food in the kitchen. A pressure cooker is a sealed pot or chamber that traps the steam generated right inside the pot as the the contents inside it gets heated up. 

As the steam keeps on building, the pressure keeps on increasing, while driving the boiling point of water right past 212°F. Since, the higher temperatures are attained with well designed pressure cookers, the food inside it gets cooked even faster efficiently and effectively.

How do pressure cookers work?

To know how a pressure cooker works, we need to first understand the science behind the pressure cooker working. This means, the working of pressure cooker can easily be understood by the subject “chemistry” which we had learnt in our 10th and 12th standards. We all know, the “ideal gas law” (or the “general gas equation”), which helps us to understand the behavior of most gases under most conditions. 

pressure cooker working

The ideal gas law goes something like this, “PV = nRT”. Where, P stands for Pressure, V stands for Volume, T stands for Temperature, n stands for the amount of a given gas which is expressed as a number of particles, and R stands for a constant (the ideal gas constant).

To understand how a pressure cooker works, let us first make a few assumptions in the closed chamber of a pressure cooker. Here are the assumptions:

l The volume (V) of the chamber doesn’t change

l R being a constant, doesn’t change either

l There is a maximum pressure that the chamber can reach, regulated by a valve system

As the pressure cooker heats up the food inside it with the help of water inside it, T goes up. Once the T starts increasing, something else must also keeps on increasing to balance the equation. Since we have already assumed that V is constant, it is more likely that the pressure (P) increases as well.

To understand this increase in pressure, let us make this simple. As the system keeps on heating, more energy is supplied to molecules of water vapor, which in turn causes them to keep bouncing around and collide randomly both with each other and also against the walls of the pressure cooker container. 

The forces that is generated with these collisions against the walls is one definition of pressure, which is based on the “kinetic model of gases”.

Now, let’s take the ultimate question that is what happens when the P maxes out? To understand this, let us take a moment of a pressure cooker containing water and chicken bones for making stock. The moment when the container reaches the maximum pressure, the temperature (T) plateaus. 

Even if we still continue to supply the heat to the container, then it means that we’re still providing energy for more random collisions between water molecules and the container. When there is no valve, the water inside keeps on heating while building pressure indefinitely. 

But in such case something has to give, which is going to be the amount of gas (n) that is going to decrease, which is nothing but the steam that keeps escaping from the pressure cooker through the pressure release valve with a rattling noise resulting the cooked chicken stock.

You can see this kind of process happening with regular stove-top pressure cookers. But when it comes to the electric pressure cookers, the cooker detects both pressure and temperature and regulates the amount of heat supplied by the heating element. 

Hence, in electric pressure cookers, neither you won’t be seeing much steam escaping nor hear much rattling. Hence, the electric pressure cookers are much quieter than that of traditional pressure cookers.

In simple terms, the sealed pressure cooker works by the increase in pressure as the boiling point of water goes up. At standard atmospheric pressure, the boiling point of water is 212°F. 

But in a standard American pressure cooker, the pressure reaches 1 atm or 15 psi (pounds per square inch) above standard atmospheric pressure*, or 2 atm, which is typically the maximum pressure limit on most cookers. At 30 psi, the boiling point of water is about 250°F.

This means that, in a sealed pressure cooker the higher cooking temperature means, faster food cooking without burning the food. Since the vessel is sealed off, it also limits the evaporation of critical volatile food flavors and aroma of ingredients in the food. This is how a pressure cooker works.

Using a Pressure Cooker at a High Elevation (Above Sea Level)

Let us come to the interesting topic of pressure cooking at high elevation. What happens when you are pressure cooking above sea level? We all know that, the general cooking times and temperatures for certain recipes differ in places such as Denver, CO, or high up in the Andes. At high altitudes, the atmospheric pressure is lower. For example, in Denver, the ambient pressure is around 12.2 psi.

You might be asking why the pressure is lower at higher elevations? This is because, most of the air molecules in the atmosphere are held close to the earth’s surface by gravity. This means that, there are very fewer air molecules above a higher altitude surface than there are above a surface at a lower altitude.

To be precise, a pressure cooker works by adding pressure above the given atmospheric pressure. This means the force that closes the valve as pressure keeps building in the chamber also includes the force of the atmospheric pressure. To make it simple, let us understand this with an example:

If the atmospheric pressure in Denver is 12.2 psi, then the absolute pressure of the chamber at full pressure is 27.2 (12.2 psi + 15 psi), nearly 3 psi less than at sea level. When you take a look at the ideal gas equation, we know that lowering pressure will also lower the temperature in a system. 

In this case, the boiling point of water in a sealed chamber cooking at high pressure will be 244.8°F, almost 6 degrees lower than the same system at sea level. In short, the lower boiling point means slower cooking and a higher boiling point means faster cooking.

So, let us go back to our question, what happens when you are pressure cooking at higher elevations? Since, a lower boiling point means slower cooking, you have to increase cooking time to accommodate lower pressure and lower cooking temperature in order to get the same results as you get in normal cooking condition areas. 

A good rule of thumb is to increase cooking time by about five percent for every 1000 feet above 2000 feet elevation.

How to Choose a Right Pressure Cooker?

Choosing a pressure cooker requires many factors consideration that decides which pressure cooker you should choose and what type of pressure cooker you must choose. A pressure cooker can be chosen based on the following considerations:

l Time saving

l Helps to retain more nutrients

l More energy efficient

l Environmental friendly

l Offers less cleanup process

l Helps to retain more flavor

l Safety of pressure cooker

l Family members

l Pressure cooker size

l Types of pressure cooker

l Compatibility

l Durability

l Price

l Features

Apart from this there are plenty of considerations that you must consider before you buy a pressure cooker. However, if you want to know more about it you can read our guide: how to choose pressure cooker.

How to Cool Down a Pressure Cooker?

If you want to cool down a pressure cooker, then there are basically 3 methods which you can use in order for cool down of a pressure cooker. The 3 methods are:

l Natural Release

l Quick Release

l Cold Water Release

Pressure Cooker Cool Down by Natural Release:

The natural release cool down of pressure cooker involves taking the heat from the cooker and allowing the temperature to gradually decrease in time until the spring-loaded lock disengages. Depending on how much food you’re cooking, remember that there could be significant carryover cooking with a natural release technique.

Pressure Cooker Cool Down by Quick Release:

The quick release of pressure cooker cool down involves the removal of the weighted jiggler or pressing off a button in order to allow the steam inside the cooker to get escaped. As you do so, the contents of the pressure cooker will boil vigorously and you can immediately stop the cooking too.

Pressure Cooker Cool Down by Cold Water Release:

As the name suggests itself, the cold water cool down of pressure cooker means, taking the complete pressure cooker under cold running water to cool down completely until the pressure cooker depressurizes and the lock disengages. 

This comes in really handy when you want your food immediately on the table for lunch or dinner. Moreover, this method doesn’t cause the contents to vigorously boil, which might be desirable for a given recipe. However, the cold water release cannot be used on electric pressure cookers.

How Does a Pressure Cooker Work?

Before anyone wants to use a pressure cooker, it is very important for them to know how a pressure cooker works? What is the science behind a pressure cooker, that it cooks food no matter what type of food it is in just few minutes. 

When you see a pressure cooker it looks just similar to a regular pot, which is slightly modified with a closing lid that can be locked in tight with the help of a rubber gasket to create a pressurized vacuum or a seal, which helps to prepare a food.

The pressure cooker works by raising the temperature of boiling water which is inside it, there by speeding up the time that it takes to boil, braise, or steam. Thanks to the tight locking of a closed lid and a pressure vessel that helps to release the steam out, making it easier for a pressure cooker to cook food faster.

To use a pressure cooker, firstly pour a minimum of 2 cups of water or pour water as per the food that you are going to cook, then place the food in the pressure cooker pot, so that the water can boil and generate steam. Now close the pressure cooker with the pressure cooker lid, lock it tightly, and switch on the gas or put the cooker on a high steam. 

The steam developed inside the pot won’t suddenly goes out and helps to build pressure inside, increases the atmospheric pressure inside the cooker by 15 pounds per square inch (psi) or in other words 15 pounds above the normal sea-level pressure. 

At this point of time, with such high pressure, the the boiling point of water is increased from 212°F to 250°F. This high temperature is the one that helps to cook the food faster.

Once the pressure inside the pressure cooker reaches the full pressure capacity (which is indicated by a gauge or pop-up rod on the lid), a pressure valve opens up, which allows the stems to escape in a constant regulated flow in order to maintain a constant temperature inside the pressure cooker pot.

Generally, most of the stovetop pressure cookers that are available in the market are usually already preset at 15 psi in order to have best cooking experience. But in some pressure cooker models, this pressure pre-setting can be set in between 10 and 11 psi or about 235°F. The reason for setting this low level pressure is that, it helps to prepare delicate foods easily such as puddings.

Now a days, the technology has moved so fast that today we have electric pressure cookers that even helps cook food much faster than traditional pressure cookers. Not only that, they also lasts longer. 

The electric pressure cookers are well designed which offers multiple settings of pressure and temperatures. They can even be pre-porgrammed or programmed to move from low temperature in order to soak beans and whole grains to higher temperatures for cooking.

What are pros and cons of pressure cooker?

The best part of having pressure cookers is that, they cook food almost by 30% faster than that of any conventional methods such as boiling, steaming, and braising. Not only that, the pressure cookers also use almost 50 to 70% less energy because of shorter cooking times. 

This means that, the pressure cookers are energy-efficient devices that helps for saving more energy. You can read more about pressure cooker advantages or disadvantages, pressure cooker pros and cons guide.

Since the pressure cookers have a closed lid, they help to retain more vitamins, minerals, and nutrients than that of foods you prepare by boiling method. This is because, the pressure cookers use very less water compared to boiling methods. 

This helps the nutrients to get dissolved easily providing a great taste of food. Not only that, the flavor of the food that is prepared in a pressure cooker is greatly maintained.

There are plenty of pros and cons of a pressure cooker. However, we have listed down few of the pros and cons of a pressure cooker here below, that helps you choose a best pressure cooker from the market.

Pros and cons of pressure cooker:

pros and cons of pressure cooker

Pros of pressure cooker:

1. You can save time

2. You can save energy

3. Pressure cookers can save you money

4. Easy to operate

5. Cool kitchen

6. Increased safety in the kitchen

7. You can cook whole meals in just a single pot

8. Closed system

9. Good pressure cookers are durable

10. Fewer nutrients are lost

11. Bacteria and microorganisms can be rendered harmless

12. Flavor conservation

Cons of pressure cooker:

1. May need some practice at the beginning

2. Pressure cookers can be expensive

3. You can’t check if your food is ready while cooking

4. You can’t adjust the flavor during the cooking process

5. You can’t look inside

6. Only suitable for certain kinds of dishes

7. You can’t account for different cooking times of different foods

8. Overcooking might be a problem

9. You may have to renew the sealing ring

10. Cheap ones may not work properly

Conclusion

If you are someone who is just started using a pressure cooker, well, how do pressure cookers work would be your definite question that first comes in your mind. Pressure cookers work on the principle of ideal gas law which goes like this PV =nRT.

In simple terms, a pressure cooker works by boiling the water inside the pressure cooker to the highest temperatures, making the steam generated not to escape easily. It traps the steam inside the pressure cooker pot and due to the intense high pressure created, the food gets cooked faster than that of conventional pots.

If you are someone new to the use of pressure cooker then we hope this guide has helped you in understanding the pressure cooker working. We advice you to always buy a pressure cooker that offers better features and lasts longer.

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