Pressure and pressure
Every time you get called in to fix your espresso machine because “it stopped making coffee,” you find yourself in a world of fluid dynamics. Of course, you don’t have to get a degree in mechanics at all to clear a clog in the dispensing group or replace the pump, but in both cases you’ll run into a problem that involves pressure and fluid flow, two cornerstones of fluid dynamics. Espresso extraction is directly dependent on both. The flow rate through the tablet determines how long the water is in contact with the coffee and therefore affects the degree of extraction. And without pressure, there is no espresso: a thick, fast drink coated with a dense mixture of oils and foam that we call crema. The process of tempering finely ground coffee produces a “pill” that is difficult to permeate with water; the density of the “pill” allows the pressure to build up, which helps extract oils from the coffee. And here it is clear that water flow limitation in the espresso machine is used to get the desired pressure.
First a small pre-infusion (pre-wetting) is required. The idea is to expose the coffee to a small amount of water (steam) in a short period of time, during which the tablet will swell and soak up water, as in a drip coffee maker. Then, when the coffee is “ready,” the machine gives full pressure of 9 bar for proper extraction. The pre-infusion concept (“pre-wetting”) was first used in semi automatic espresso machines, in which the “tablet” was initially exposed to a pressure from the boiler (for example 1.5 bar) before the piston applied a higher pressure (11 bar, gradually reducing to 7-9 bar towards the end of the process). In these machines two independent pressure systems were used.
Now let’s talk about water flow restrictions in espresso systems (often called nozzles). In these systems, prewetting is achieved by reducing the water head through the pill, and it takes longer to get a pressure of 9 bar. It is a process similar to pumping a wheel to 35 psi.Inch through a nozzle the size of a pinhead. When you pump up to 35 psi.inch? When you get frosty from sitting on the side of the road. Using the water flow limiter to control pressure can also be done in a more sophisticated way: a type of manual horn group is now common, which allows the barista to vary the water flow pressure by opening and closing the valves in the center of the group.
This process is full of surprises, because the pressure is not in a direct linear relationship to the size of the hole in the flow restrictor. A slight opening of the valve can result in a sudden increase in flow, allowing the pressure to equalize on both sides of the valve. You’ve seen this process in action if you’ve ever made coffee in a manual carob machine and noticed that turning the lever a few degrees dramatically increases the output pressure. Systems in which the pressure is controlled by limiting the head are very capricious.
An even more sophisticated way to vary the water flow and pressure is possible with an adjustable pump, as in the La Marzocco Strada EP coffee machine. In this apparatus, an electric pressure sensor reports the current pressure value to the electronic unit of the machine, which compares it with the profile used by the baris and adjusts the speed of the pump of this group to achieve the desired result.
There is another way to control the pressure: the use of a spring loaded valve. Take, for example, the expansion valve. This is quite a powerful spring, usually yielding to a pressure of at least 12 bar. When a force of 12 bar is applied, the spring compresses slightly and releases a few drops of water, which reduces the pressure only slightly below 12 bar (and then closes).
Such an elementary-arrangement spring valve is also very much in demand for gentle pre-infusion, although it does not allow you to control the flow. “Old-fashioned” pre-infusion valves, popular for decades, are still used in Kees van der Westen’s Speedster semi-professional machines; these valves perfectly “absorb” the initial pump pressure, acting much like shock absorbers in a car suspension; only when the valve fully opens, a full 9 bars of pressure is applied to the pellet.
There is another topic for discussion, and unfortunately this is not another cool example from mechanics. The pressure drop occurs when the working fluid, such as water, is pushed by pressure through the pipe from point A to point B. Even in a straight section of copper tubing, the frictional force slows the flow of water molecules slightly and reduces the pressure. In a sense, this is similar to manual pressure drop using one of the above methods. However, in this case it is not possible to regulate the pressure precisely.
The most common way to do this is to set the pressure to 9 bar (for example, by using a spring loaded bypass valve on the pump to adjust the pressure). However, 9 bar on the sensor does not mean the group is getting 9 bar. If the sensor is installed in an espresso dispensing system well “above” the group, it may show a higher value than what is actually delivered to the group, because the water pressure drops as it moves from the measuring point to the dispensing point. And sometimes the sensor shows less because the machine manufacturer used too thin copper pipe to connect the dispensing system to the sensor.
In general, the only way to know the group pressure accurately is possible if you measure it directly in the group, using an instrument that has about the same capacity as a coffee tablet. The best and most original of these is the Scace, named after its inventor and one of the patron saints of espresso mechanics, Gregory Scace. While this gadget isn’t cheap, it proves invaluable if you want to set up your espresso machine in the best possible way. And that, in the end, is our job: to support those in the coffee industry so that their drink is the best it can be.
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Repair of professional coffee machines: group grids replacement replacement of group seals replacement of group nozzles replacement of the pressure switch replacement of the flowmeter replacement of the copper tubes or replacement with PTFE replacement of the manometer replacement of the heating element replacement of the return valve replacement of the break valve replacement of the overpressure valve replacement of solenoid valve coils replacement of the valve core replacement of the three-way valve assembly replacement of the two-way valve assembly stainless steel polishing replacement of the fill/drain valve
Repair of electronics, control boards, membranes and panels.
Adjusting the parameters of the machine: adjustment of boiler pressure adjustment of pouring pressure adjustment of flow by selection of nozzles adjustment of temperature of pouring (water in the exchanger) programming of doses
Stock of spares for LaCimbali, Casadio, Nuova Simonelli, Marzocco, Mazzer etc.д.
Preparation of espresso
Semi-automatic. uses ground coffee, which is poured manually by the user. After making espresso the used powder is removed by the barista. It also controls water pouring.
Automatic. the ability to get espresso without user input. This device produces a “pill” of coffee ground in a built-in grinder. In addition, the coffee maker automatically doses the water spill.
Types of carob coffee makers
There are several types of carob coffee makers.
Steam cone coffee maker
A steam coffee maker prepares a drink at a low pressure, which reaches up to 4-5 bar. The water itself is heated to boiling point and turns into steam. Then, under pressure, the steam passes to and through the ground coffee. It makes a better cup of coffee than the drip version. True, the pump model tastes better, because coffee loses its taste at temperatures above 96 degrees.
Important! Experts say that it is impossible to make high-quality espresso in such a coffee maker. There are only few premium models that can do it.
Pomp Coffee Carob Maker
The pump coffee maker makes the beverage faster, because the water is quickly heated up to 95 degrees by an electromagnetic pump. High pressure, which can reach 15 bars, also has an effect on brewing speed. Besides, the coffee in this appliance will taste much better.
Home units have a vibration pump in their design, while professional units are equipped with a rotary pump.
How to choose a coffee maker
Some people like coffee, some don’t. This material is for those who are not indifferent to the invigorating drink. Here we will try to answer the question How to choose a coffee maker? Let’s talk about what should be determined before going to the store, what to clarify in the store. So you can easily prepare your favorite coffee at home.
Since 1800, when the coffee maker was invented, a lot of water has passed, as they say. Drinking a lot of coffee. The French priest De Belloy is to be thanked for the coffee machine. He gave the world the drip coffee maker. Water has been dripping through a special filter, filled with ground coffee. Actually, the principle of drip coffee makers has not changed (more details below). In 1827 the first geyser coffee makers appeared, in which coffee was made by passing hot water and steam through it multiple times. In 1840, the vacuum coffee maker appeared, in which water, after irradiating a layer of coffee, was returned back into the supply tank under vacuum, taking with it the flavor and aroma of the ground coffee beans. However, such coffee makers were not widespread. The first compression-type coffee maker, in which a fragrant beverage was prepared by passing high-pressure steam through a layer of ground coffee, was invented in 1855.
Of course, ancient coffee makers had many drawbacks. Many of them were simply dangerous. There were problems with the quality of the cup. Not all machines were able to provide a good extraction of flavor components from coffee beans. Many of the coffee makers (e.g. compression coffee makers) were very big and required a lot of coal to be constantly refilled. Another big problem was that it took a long time to find the optimal combination of brewing time, quantity of coffee, steam pressure and temperature. After severe and lengthy experiments it was found experimentally that the adequate temperature for espresso is in the range of 86 to 93C. The pressure level should be 5-9 bar (the so-called royal range).
Perhaps the year 1901 could be considered the year when coffee really made its way into the masses. It was in this year, November 18, that Italian engineer Luigi Bezzera revealed his invention to the world: the espresso machine. On the whole, it was a rather large boiler. The lower part boiled water, while the upper part created conditions for pressurized steam. There was also (and this can be called the main innovation) a special coffee group with a Holder (a special container with a filter) for coffee on the boiler. Here, by opening a lever valve, the barista (now a coffee specialist, at that time he was just a man working behind the bar) poured hot water. Then the lever had to be lowered to close the water valve. The next step was to open the steam valve on the coffee pod in the Holder. Pressurized steam pushes water through the coffee, it takes with it most of the flavor-aromatic filling of ground coffee, and, passing through the filter holding segment, ends up in the cup with a ready beverage.
Further technologies were developed, improved and, as a result, today, the user has access to various ways of brewing coffee using different types of coffee makers. Below we are going to talk in detail about the coffee makers, currently represented in stores. Let’s note what you should pay attention to when buying them.
The most popular today is a drip coffee maker. These are affordable and easy to use models, which, however, are quite able to provide the user with a decent quality coffee. The principle of operation, as already noted, has not changed since the nineteenth century, hot water is passed through the ground coffee placed in the filter segment of the coffee maker, without any pressure. Since the ground coffee in the drip coffee maker is not rammed, it does not create a tablet, the hot water (heated in the boiler) passes through it simply according to the laws of physics due to its own gravity. Water flows, you might say, drop by drop, hence the name of coffee makers. Note that the drip coffee maker only makes American-style coffee (Americano, regular coffee). Fans of espresso and espresso-based drinks should look no further than carob type coffee makers or automatic espresso machines. below).
Despite the simplicity of a drip coffee maker, there are several things to consider when buying it. Let’s start with power. If you like your coffee strong you can buy a less powerful maker (700-800W). It takes longer to brew, but the drink is stronger. It’s simple, with less power it takes more time to brew, because the water heats slower and therefore takes longer to interact with the ground beans. And if so, it means that the drink will be strong. Alas, in filter models this often means that it is also quite bitter. It is better to buy a coffee maker with at least 1000 watts of power. In this case, however, you will need a little more ground coffee beans (especially if you want a stronger drink), but the output of the finished drink will be the same as in a less powerful machine.
There are also drip coffee maker models in stores, which have an automatic control of the strength of the finished coffee. Coffee maker, depending on how many cups of coffee you need to get as a result of its work, controls the process of heating water and passing it through a coffee powder to get a drink of the strength selected by the user. These models are usually a little more expensive than conventional.
The coffee beaker in drip coffee makers is usually made of glass. Modern coffee makers often have a heating element under the flask to keep the coffee hot for a certain period of time (usually about 30 minutes). There are also models with metal flasks. Such flasks, as a rule, themselves are able to keep coffee hot for a long time Thermos flasks. The flask must have a convenient handle, protected from excessive heat, so that the user can easily and safely pour the coffee into the cup. Flasks come in different sizes (volumes). From small, for 5 cups, to quite a big for 10-15 cups. The maximum capacity (in liters) for a beverage in a household drip coffee maker is now 2 liters. There are models with batch coffee (0.2, 0.3 liters) where the coffee usually comes straight into the cup (or cups) supplied with the coffee maker.
Another important point drip coffee maker filter. Filters may be paper disposable. They are sold in household appliance stores in packages of 100. Their main advantage is that after use such filter with spent coffee just thrown away, no need to clean it. But there is a need for additional costs. A nylon filter is often supplied with the coffee maker. Producers usually indicate that it lasts for 60 coffee cycles. But with the proper care such a filter lasts much longer. The so-called gold filter is the same as a nylon filter, but with a special coating of titanium nitride, which increases the life of the filter even more.
It is important for drip coffee makers to have an anti-drip system. This sounds like an oxymoron. But it is the point at which the user picks up the coffee beaker to pour the coffee into the cups. At this point, for example, if the coffee is still brewing, the beverage valve should be blocked (of course, it is desirable to quickly put the flask back, so as not to overfill the coffee compartment with water).
Important points when choosing a drip coffee maker are also: the presence of a holder for coffee filter compartment (so that it can be simply pushed aside if necessary, without removing it from the coffee maker), the ability to program the time off and on the coffee maker. Note that most residential drip coffee makers are only able to work with pre-ground coffee. But there are models with built-in grinder and automatic delivery of freshly ground coffee into the filter compartment. (very small, for a cup of coffee) up to 10-12 thousand rubles. Rubles. On average, a quality drip coffee maker with a flask for 10-12 cups will cost 1.5-3 thousand dollars. rubles. The most famous brands are Bosch, Philips, Scarlet, Tefal, Moulinex, Melitta, Russel Hobbs, Bodum.
Geyser Coffee Makers
You don’t have to go to Kamchatka to see geysers. You can have your own little geyser geyser coffee maker at home. True, you will not see any geyser in your kitchen. It bubbles inside the coffee maker. But know that the principle of operation allows to call these devices distant relatives of the majestic Kamchatka or any other geysers.
Geyser coffee machines consist of a metal vessel and special dividers that separate water and ground coffee from each other. The lower compartment is filled with cold water. It rises and passes through the filter with the ground coffee as it boils. Extraction of flavor components from coffee into water. The upper compartment of the pot collects ready brew. There are also geyser models where the coffee is brewed with steam. When the water is boiling, steam passes through the coffee through a special tube and condenses in the upper compartment. The process of passing water or steam through the coffee can be repeated several times, for a more intense flavor and greater strength. It takes about five minutes to brew coffee with these devices. There are electric geyser coffee makers, and some just put on the stove to make coffee. Alas, the fact that the water in a geyser coffee maker must necessarily boil does not affect the taste of the finished drink.
Geyser coffee makers are sold in Russian stores, although this method of brewing coffee is not very common (hence the assortment of coffee makers is small). When buying a geyser coffee maker, you should consider the size (capacity). If your coffee maker is designed for 6 cups, you will have to brew the same number of cups each time due to the construction of the machine. But there are models on sale that allow choosing the desired number of cups (for example, 3 or 6). Depending on the cup capacity, the appliance power also depends on. Output of a geyser coffeemaker varies from 450W to 1000W. Do not buy a large, but low-powered coffee machine. It would be nice if the device had a number of additional functions: auto-off after making coffee, maintaining the temperature of ready coffee, a timer, an autonomous heating base with the ability to rotate the coffee maker for 360º (as in modern electric kettles), light indicator, strength control. In Russia, mostly electric geyser coffee makers are now available DeLonghi and Bialetti.
Coffee makers for Turkish coffee
There are also electric makers for Turkish-style (Turkish-style) coffee making. These are simple devices, replacing the traditional turks, jezvas (if you can not cook on the stove, but we like this kind of coffee). Typically, oriental coffee maker consists of a brew vessel (it’s metal or plastic), which is installed on a special base. It is desirable that the latter was with the possibility of rotation of the brew vessel at 360. Although there are models without a base. The heating element in the brew vessel is hidden. The volume of the brew vessel is usually from 0,25 to 0,4 l. Power 500-1000 W. It is worth understanding that the more powerful the coffee maker, the faster the coffee will be ready. Users of the most powerful models (800, 1000 watts) often complain that the coffee is made too quickly, you do not have time to keep track of it, and it runs away. Unfortunately, these brewers cannot yet control the degree of readiness of coffee by themselves and turn off in time. This type of coffee maker should preferably have a light indication. The main brands available: Sinbo, Ves, Saturn.
Along with drip, espresso makers are now the most common in the home. There are two types of espresso machines: steam and pump. In a steam coffee machine that’s what happens: the water is poured into a boiler, it boils there for about two minutes, turns into steam, which, when it reaches the desired pressure (4-5 bar, depending on the model), passes through a filter with a tamped coffee removable metal (but not plastic)!) filter horn. True, the water in the brewing process boils in the same way as in a geyser coffee maker. And this is wrong coffee taste suffers.
What is Espresso Machine BAR Pressure?
In pump models, according to KEDEM.RU, you get a better espresso coffee. Here the water does not need to boil. It heats up to about 90C. Then, under the pressure created by the pump, it passes through a coffee tablet in the filter horn. Salespeople in stores usually convince trusting customers that 15 bar is the best pressure for making espresso. And that this is exactly the pressure under which the coffee is made in the coffee maker of this or that manufacturer. This is not the case. Preparation usually takes place at a pressure no higher than 5-7 bar, depending on the model of coffee maker. Of course, the manufacturers indicate in the characteristics of their devices 14-15 bar pressure, but this maximum capacity pump, which in the process of making coffee just is not required (and not every coffee machine can withstand this pressure can break the horn).
Espresso makers, both steam and pump based, are often able to create milk foam for cappuccino or other milk-based drinks. This is helped by the special steam pipe of the cappuccino maker. In most conventional models of espresso machines, this involves placing a mug of milk under the cappuccinator, heating and steaming the milk, and then transferring the milk foam with a spoon into the finished coffee. You should agree that this is not very convenient. So, as a rule, the owners of such coffee machines make a manual cappuccino once or twice, and then they safely forget about this possibility. But there are also espresso makers with the ability to automatically prepare cappuccino (milk foam is pumped directly into the cup from a special milk container with an integrated cappuccinator). Such models, of course, are more expensive than usual. There are also espresso machines that allow you to brew coffee in ways other than the traditional method (with the ground coffee being crammed into the beaker, etc.).д.), but also in pods (coffee is compressed in paper filter packs).
When buying an espresso machine, you should also consider the availability of a removable drip tray. The coffee cone must be metallic (usually stainless steel). It’s nice if the cone has a double nozzle. you can make two cups of espresso at once. Espresso mug warming (espresso should be poured into slightly warmed cups) is a nice extra option, available in some espresso makers. The built-in tempera (coffee thickener in the horn) is a welcome addition. It must be possible to quickly cancel the coffee preparation (even if the process has already started). It is also desirable that the coffee maker does not start if there is no water in the corresponding container (it is better if the container is removable), shut off when overheated. Also note that when using an espresso machine you will need a certain grind of coffee, especially for espresso. If you want to grind coffee at home, you’ll need to buy a grinder with the possibility of setting the grind level (with different grades).
Capsule coffee makers are called “lazy brewers”. The point is that all you need to do to make coffee is to place the capsule into a special coffee maker compartment, close this compartment and press the button to make the coffee. While brewing, the capsules are usually pressed and the coffee is pierced with a special hollow needle. This needle (there may be several of them) is used to pressurize water heated to a certain temperature into the coffee. Water takes away from the ground coffee flavors and aromas and falls into the cup the beverage is ready. The spent capsule is thrown away into a special container. Some models use capsules, in which the coffee is not pressed (for example, T-discs for Bosch Tassimo capsule coffee machines). The technology of a beverage in such models slightly differs from a classical capsule, but in general the principle of operation of capsule models is the same.
Note that in many capsule coffee makers, it is also possible to prepare dairy coffee drinks. Some capsules contain dried or concentrated milk, but there are also capsule makers models which are equipped with a special milk container with an integrated cappuccinator. Also capsule coffee machines are capable of making tea, drinks based on various herbs (capsules with the appropriate filling).
The inconvenience is that the user has no choice: he only drinks what he is offered by the capsule manufacturer. Only the varieties and types of coffee that the manufacturer deems it necessary to introduce in your country. No experiments because each capsule machine works only with its own type of capsules. Other capsules are not suitable for this type of coffee machine. Besides, capsule coffee is quite expensive compared to regular ground or whole grain coffee. A cup of coffee costs a lot more for the user (a pack of 16 coffee capsules costs at least 300).
When buying a capsule coffee maker there are a few points to consider. It is desirable that the power of your capsule maker should be at least 1000-1200 watts (the amount of power determines the time it takes to brew coffee). The pump pressure (which is also present here) should be set to a maximum of 15 bars. Pressure models up to 19 bars. But remember that this is the maximum pressure of the pump, actually making coffee in capsule models usually occurs at a pressure of 5-8 bar. There are, however, models with a pump pressure of about 4 bar, this is due to a slightly modified coffee technology (Bosch Tassimo line). The volume of the container for clean water, preferably it should be at least a liter. Then you will not have to refill it too often. It’s good if the container is removable. There are models with a water filter built into the container. A capsule coffee maker should switch off automatically after a certain period of time after making coffee. Also note the presence of self-cleaning modes drip coffee maker.
The main brands of capsule coffee makers that are available in Russia and have proven themselves: Nespresso Krups, Krups Dolce Gusto, Nespresso DeLonghi, Bosch Tassimo, Cremesso.
Combination coffee makers include models that allow the user to make espresso and Americano. That is, it is a symbiosis of espresso and drip coffee maker. Anyone who likes both methods of coffee preparation will like this coffee maker. Combined coffee makers take less space (than two separate devices), but require care of each segment. Adequate manufacturers (brands): DeLonghi, Krups. Bialetti Mokona combination coffee maker, which can work both as a geyser and espresso coffee maker, is also available in Russian online stores. But that’s not all. It can also work with coffee pods, as well as with coffee in capsules (Bialetti brands). It has the possibility of making cappuccino (manual operation). The ultimate all-in-one coffee maker for all occasions.
Automatic Coffee Machines
An automatic coffee machine is a sophisticated household appliance that allows the user to make coffee at the touch of a button. And it can be ristretto, espresso, lungo, cappuccino, coffee latte, even hot chocolate. There are almost a dozen kinds of coffee and other drinks available in modern coffee machines. Modern coffee machines are complete coffee cycle appliances. The user pours the coffee beans into the appropriate compartment and ends up with a finished drink. But it’s also possible to use pre-ground coffee on request.
Coffee machines are a separate class of devices. When buying them you need to take into account a lot of different points. KEDEM. RU will prepare a special material on this topic in 2013. Here we inform that the main brands: Krups, Philips-Saeco, DeLonghi, Jura, Melitta, Bosch.
. All in this article are given by results of monitoring of Russian internet-shops. As of April 2013. Depending on the region, the cost of equipment may vary.
To start with my formula: the taste of coffee made with equipment of one class (in this case I am talking about automatic coffee machines) depends on 80% of beans used, 10% on the particular model of coffee machine with which you brew it, and 10% on the right settings that suit the beans and your tastes.
For questions on choosing coffee for your coffee machine, read my profile. If you are asking the questions in the title, I assume that you have already purchased a coffee machine, and its replacement is also not the subject of this article. Here, however, let’s break down how you can affect the remaining 10% of the flavor in your cup. But in any case, it’s important to know that the settings below cannot radically change the taste stored in the beans. No matter what you do, you can’t get rid of the acidity completely if there is a lot of it in the original beans, and vice versa, you can’t get rid of the bitterness completely if the beans are roasted properly.
For whom are carob coffee machines good?
Before describing it in more detail, I’ll start with the main idea, which the reader needs to understand:
A normal carob coffee maker narrowly specializes in espresso and espresso-based drinks. That’s why they are also called espresso machines
So if you are fully aware that you prefer Turkish coffee (from a turkey or electric turkey), geyser coffee or, for example, filtered coffee (as an alternative brew), you basically do not need a coffee carob. Trying to turn a carob into something close to this is a lot like using a nose for dental hygiene.
On the other hand, for espresso and espresso-based drinks, a carob is a necessary and sufficient piece of equipment. Here I’m leaving out the brackets of coffee machines, because the grain machines and competent capsule machines are actually trying to bring the process closer to brewing in a classic cone.
What is a coffee machine?
A coffee machine is an electrical appliance for the automatic preparation of coffee and coffee-based drinks at home. Unlike conventional coffee machines, it grinds natural coffee beans, controls boiling water, whips up or heats milk, and performs self-cleaning to remove limescale and dirt.
Important! It is multifunctional and is suitable for people who like to experiment and try new drinks. Not only espresso, but also latte, cappuccino with creamy foam, macchiato or lungo are easy to brew with a coffee machine.
Professional Coffee Machine Diagram
This article will be useful for everyone who works with professional coffee machines. Before you start working you should understand what is what and study the process of coffee making in coffee machines. First, let’s study the coffee machine from the outside:
- Spill button. button to start/stop espresso spilling through the group. In semi-automatic models you turn the button on and off manually, in automatic models the extraction will end by itself (according to programming). The automatic model has five buttons per group: to program different drinks. espresso, double coffee, ristretto, etc.д.
- Cup warmer. passive/active.
- Pressure gauge of the pump informs about the coffee machine failure (if the pressure is not at 9 atm).
- Pressure sensor in the boiler. signals the coffee machine is heating up and ready for operation. In working mode, the steam pressure in the boiler is at 1, 1. 1, 5 atm (depending on the model). When using a large volume of boiling water from the boiler the pressure may drop. In this case, it is necessary to wait a few minutes until the coffee machine returns to normal operation.
- Steam tap. supplies steam from the boiler for foaming milk.
- Holder. is the cone in which you put the pre-ground coffee to brew the beverage. Is inserted into the group.
- Boiling tap. provides boiling water for tea.
- The group. the system for making coffee.
- LCD display. allows you to program individual modules of the coffee machine, to account for and control some processes.
- Automatic cappuccinator. allows you to whip milk for cappuccino in automatic mode.
Let’s move on to the part concealed by panels. This diagram shows the most popular coffee machine model with a single boiler. Coffee machines with two boilers are found in such manufacturers as Brasilia and Dalla Corte. Separate so called independent boilers allow to program the temperature of water in each group separately for preparation of different coffee blends (for example, 100% Arabica blonde roasted at 94 degrees and 80/20 French blend which can be prepared at 92 degrees). One boiler is used for dispensing boiling water for tea, and another for heating cups for espresso.
- Copper or steel tank; filled with 70% water that is heated to 115-120 degrees. The main task of the boiler, as a coolant, warms the water flowing in the heat exchanger cup to make coffee. This water is also used for tea.
- Heats the water in the boiler.
- Hollow tubes placed in the boiler, into which fresh water is pumped, heated from the boiler and fed to the group. Thanks to this system, every coffee is brewed with fresh water.
- Performs two functions: water supply to the group and to the boiler. The pump can be connected to the water system or to a bottle.
- Keeps the water level in the boiler.
- Prevents the boiler from exploding by depressurizing it.
- Removes residual water from the group, at the end of espresso extraction.
- Pump pressure sensor.
- Valve that supplies water to the group.
- Dispensing group.
- Gives out steam.
- Boiling water will come out.
- Indicates that the coffee maker is in operating mode.
- According to the programmed volume, turns off the water flow from the group. (Only in automatic coffee makers with portion-by-volume programming).
Special mechanisms measure the required volume of powder and water, warm the cups before pouring, like in coffee machines. Pods and the drip brewing method already make it possible to experiment with water pressure. In pressurized coffee makers, boiling water passes through a layer of ground coffee with a pressing force.
Pressure largely determines the taste of the coffee, its richness and brewing speed Here, brewing is fast, and due to the high pressure, the coffee maker makes high quality coffee. often than not, the higher the pressure in the coffee maker, the better the coffee is, although this is not always a fair statement.