Foam generator: principle of operation and design, production of various types on your own

The use of foam is among such human conjectures as the use of tools, the mastery of fire, the invention of the lever, wedge and wheel. Suffice it to remember that the bread we eat is frozen foam. In modern life, foaming is widely used, as are foam generators - devices for producing it in large quantities. In this article we will look at how to make a foam generator with your own hands for a fairly narrow but relevant area of ​​application - contactless car washing and other household purposes. And in this by no means wide segment, as we will see, various designs with their own characteristics are used.

General information

Rydvan “armored cars”, painted on the ground in several layers, went to the same place where gasoline cost 7 kopecks. or 10 cents per liter and its consumption by passenger cars (!) is 30-50 liters per 100 km on the highway. Nowadays cars are painted with one very thin layer directly onto the metal. Modern paints are very durable, but rubbing the car with a brush or sponge is still not recommended. Nowadays, cars are washed first. in a contactless way. Let us remind you, just in case: apply the car shampoo solution to the contaminated surface, wait a while until the surfactant eats away the dirt, and rinse it off with water. The car wash community is split into two irreconcilable (just kidding) camps: one, the surfactant must be applied in the form of an emulsion without foaming; others believe that only active foam cleans well. Both give valid arguments in their favor, but since you are reading this text, then you are most likely a supporter of foam washing.

The “Penomoi” (another joke), in turn, are divided into two sects (and this is also a joke): “low-crats” and “high-crats”. Washing with low expansion foam (on the left in the figure below) requires a short wait time before rinsing (usually up to 5 minutes). Liquid flowing foam penetrates well into hard-to-reach places, but due to runoff, a lot of it is lost, and along with it, expensive car shampoo. Washing also requires a lot of water, and there may still be streaks that need to be wiped off with a soft sponge. To obtain high-expansion foam, and again water to wash it off, you need 1.5-3 or more times less water, the dense sticky “coat” (on the right) almost does not drain, but you have to wait up to half an hour for its full effect, and Dirt may remain in narrow crevices.

Car washing with low and high expansion foam

The question is also about price

Purchase a foam nozzle for the washing gun, like the one on the left in the same figure. above, no problem: they are inexpensive, and are often included with the pistol kit. But the nozzle only produces low-expansion foam. The prices for high-expansion foam generators are of a different order, plus you need a fairly efficient air compressor. Therefore, we will next consider how to make a foam generator for car washing, which allows you to obtain foam of various expansion rates with a conventional compressor for inflating tires or a homemade one. The price of simplification is reduced productivity and resp. lengthening the washing cycle. But for periodic washing of your car or for an on-call personal washer, this is not a problem.

Industrial foam generators: purpose, principle of operation

As already mentioned, foam generators are very popular products. They are used in service stations (car washes), fire fighting, pharmaceutical and food industries.

The active composition of the foam promotes high-quality cleaning:

• production equipment;
• road transport (from the inside or outside);
• industrial premises (floors, walls, etc.);
• sidewalk paths and swimming pools.

The action of the foam is aimed at cleaning the surface, removing dirt and dust, disinfecting, and so on.

It is thanks to the complexity of action that foam generators have become so popular.

Structurally, the device consists of three elements:

• a cylinder containing compressed air;
• release gun, which provides convenient foam supply;
• mixer elements.

One of the main parameters affecting the functionality of the device is the capacity of the cylinder, which can be from 25 to 100 liters. There are some models that hold 24 liters.

The material used for manufacturing is stainless steel or ordinary steel.

The principle of foam formation occurs in two stages:

• a foam composition is formed, which has a low expansion rate and is not yet suitable for use;
• the mixture is supplied to a special “tablet”, which forms the required composition with the required density.

Terminology

There are hundreds of types of artificial foam, and many dozens of types of foam generators (without taking into account design features). Therefore, in order to avoid confusion in what follows, let’s define the terms:

• Foam is a finely dispersed system in a dispersion medium. Simply - a liquid, elastic, elastic or solid bubbly substance in which the total volume of the cavities of the bubbles is at least several times greater than the total volume of the partitions between the bubbles.
• Foaming is the transformation of the initial dispersible medium into foam.
• A foaming agent is an initial dispersible medium, a substance or a mixture of substances that foams under certain conditions.
• Filler is a gas that fills foam bubbles. There is a vacuum in the bubbles of unfilled foam.
• A foam generator or foam generator is a technical device, the inputs of which are supplied with a foaming agent and filler, and foam comes out of the output. An unfilled foam generator is a vacuum chamber with continuous pumping into which active filler is supplied.
• Bubbler (foaming agent) is the part of the foam generator in which foaming occurs.
• An active bubbler arouses the foam in one way or another, acting mechanically, pneumatically (bubble bubbler), or through electrical, chemical or electrochemical processes.
• A passive bubbler is a solid, chemically resistant dispersed system through which the foaming agent sol in the filler is forcibly pumped. Foaming occurs due to microturbulence in the pores of a passive bubbler.
• Active foaming agent - does not require the supply of filler, because It foams itself under certain conditions (heating, pressure relief, adding a foaming reagent, etc.).
• Foam expansion ratio is the ratio, per unit volume, of the total volume of the filler to that of the foaming agent. For example, if it took 1 ml of foaming agent to create 1 liter of air foam, then its multiplicity is 999.

Note: modern special-purpose foam generators can produce foam with an expansion ratio higher than 1000. For contactless car washing, foam with an expansion ratio from 15-20 to 50-70 is used.

Why do you need a foam generator?

Unlike conventional low pressure sprayers, foam generators produce more uniform, consistent and finer foam. This property is used:

• for contactless car washing;
• extinguishing fires (a fire extinguisher is essentially a powerful foaming agent);
• as a decoration at “foam parties”.

Household foam generators are used for washing cars, wheels and, less commonly, for cleaning surfaces (in the garage, workshop, on sites). In rural areas, this device will be appropriate not only in personal plots, but also in bus depots, public utilities, and service stations. A mobile foam generator is convenient to store in the garage or even in the trunk; you can take it with you so that you can wash your car when entering the city, without spending money on a commercial car wash or using it only to wash off the foam, which will significantly reduce the cost of the procedure. It's no secret that at self-service car washes, most of the cost comes from foam treatment. Having a mobile generator in the trunk, you can safely skip this step.

Foam generators are actively used when washing cars

Operating principle

So, we will design an air-liquid foam generator with a passive bubbler. This type of this class of devices is technically simple and accessible for self-production, and its performance and foam expansion indicators are sufficient for an individual car wash. Air-liquid means that the foaming agent is liquid (a solution of car shampoo in water), and the foam filler is atmospheric air.

The principle of operation of a foam generator of this type is illustrated in the figure:

Operating principle of a foam generator for car washing

Depending on the method of supplying the foaming agent and filler, this device can be structurally designed:

• Injection (supercharged) - the foaming agent and filler are supplied forcibly under pressure. The possibilities for adjusting the expansion rate and foam consumption are the widest. “Range” (see below) is the greatest. Air compressor – low or medium performance for a pressure of 4-5 ati (4-5 bar (approx.) or 55-70 psi). Shampoo consumption for washing a passenger car is 30-50 ml; water for foaming agent – ​​5-6 liters.
• Direct ejection (supercharged) - air is also supplied forcibly and sucks the foaming agent from a supply container with atmospheric drainage, as in a cologne atomizer with a pear. Structurally simpler than before. type (no need for a pressure vessel), but the ability to set foam parameters is somewhat narrower. Compressor for pressure from 2-2.5 ati (bar, or 29-36 psi); water and shampoo consumption approx. 1.5-2 times more than before. case. With a low-performance compressor (for inflating tires), it is possible to obtain only low-expansion foam. Most foam nozzles for washing guns are built according to this scheme.
• Reverse ejection - a jet of foam concentrate from the nozzle draws in atmospheric air. Its flow rate is determined by the pressure drop at the nozzle exit, which cannot be more than 1 atm (0.987 bar or 14.5 psi), so it is impossible to obtain high-expansion foam. The additional parameters relevant for a car wash (see below) are unsatisfactory, but using a model of such a device using a washing gun with a mud cutter and cutting a plastic bottle with a “waist” (below in the figure), you can clearly understand the principle of operation and learn how to adjust the foam.

Extra options

The performance of a foam car wash is significantly influenced by additional parameters of the foam generator:

1. range of foam jet ejection (range) - the greater the distance you can “shoot” a given area, the less time it takes to wash and the better its quality will be, because the foam sprayed at the beginning has less risk of “overstaying”;
2. homogeneity of the jet - washes the car preeminently. foam from the dense core of the jet, and the flakes that form the halo flow down more uselessly;
3. transverse compression of the jet - washing foam with a compressed “shovel” results in much less loss of surfactants than with a “broom” that is round in cross section.

Injection generators “shoot” the farthest, 3 m and further. The uniformity and compression of the jet is largely determined by the spray nozzle, see below.

Another generator

Some foam nozzles for washing guns are produced with double bubbling, active pneumatic and passive. Air is pumped into the supply tank through a sprayer in the form of a stream of bubbles through a foaming agent, above the surface of which a cap of low-expansion foam is formed. When you press the shutter, part of it enters a chamber with a passive bubbler, which increases the foam expansion rate. Due to this, the range of jet emission sharply decreases, but a household pump sprayer can be very easily adapted to a generator of this type for washing small surfaces (see below), and the possibility of using it for its intended purpose is not lost.

Option No. 3 – foam generator from a plastic canister

Not every car enthusiast has the metal containers necessary to implement the first version of the foam generator. As an inexpensive alternative, you can use a regular plastic canister. To assemble the device you will need an angle grinder, wrenches, a nozzle, a compressor, pipes, pipe fittings and a gun. The work is carried out according to the following scheme:

• First you need to cut a 50-centimeter piece of an inch pipe using a grinder. Inside it you need to stuff a sufficient amount of ordinary fishing line with any cross-section. This material will serve as a foaming agent (similar to the polyethylene sponge that was used in option No. 1).
• Plumbing plugs should be tightly secured at both ends of the pipe. It is important that these fittings are threaded. A T-shaped adapter is attached to one plug, and a fitting is attached to the other.
• Flexible hoses with taps are attached to the T-adapter.
• One terminal of the foam generator will be connected to a container with detergent, and a tube coming from the compressor will be connected to the second.

This method can be implemented in different variations. Below are possible options, among which you can choose a suitable modification at your discretion.

Which one should I do?

Types of homemade foam generators

The choice of the type of foam generator for self-construction is made based on the existing production and economic needs, the container for consumables and the allowable costs of creating the installation (see also Fig.):

1. from a household pump sprayer - only a mini-generator with double bubbling. But with its help you can wash the most dirty places of the car: wheels, wheel arches and body sills (see figure below), motorcycle (sorry - bike), scooter/moped, bicycle, rubber boots after going out into nature or working in the garden;

   
   Washing car wheels and wheel rims with foam

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2. from a pump portable garden sprayer - the same foam generator without a compressor, but suitable for washing a compact city car. With a compressor - any of the types described above. The best base unit is the Russian “Beetle”, its tank can hold 6 bar without any problems;
3. from a car fire extinguisher - a supercharged foam generator for washing a personal car or minibus/van of the Gazelle type. "Ford Transit", "Mercedes Transporter", etc. A compressor for inflating tires or from a refrigeration unit will do;
4. from a stationary fire extinguisher - a foam generator for professional washing, incl. heavy vehicles. Compressor - with a capacity of 120-150 l/min (for example, based on an onboard ZIL-130);
5. from a canister, bucket with a lid, etc. – ejection with supercharging. The generator parameters are determined by the type of compressor available.

What containers are best to use in homemade foam generators?

When assembling this device, you can use almost any tanks that are available on your farm and are capable of operating at a pressure of 3-5 atmospheres. The choice of a specific option depends on what is your priority: the cheapness of a homemade device or its reliability.

If savings are more important, you can use iron and plastic cans, garden sprayers and similar containers. But it should be borne in mind that when working with such containers, you need to monitor the pressure in the foam generator. Exceeding this value slightly could cause the tank to explode, damaging your vehicle, or causing injury to you.

From a safety point of view, metal propane cylinders are the best option. Such structures are designed for dozens of atmospheres, so it is quite difficult to destroy them with conventional compressors used at home. Obviously, a foam generator with such a cylinder will be more expensive to produce, but this is fully compensated by its durability, safety and resistance to increased internal pressure.

The device of "real"

For high-quality car washing, you still need an injection or “direct” ejection foam generator. Structurally, they are largely similar, so let’s look at both at once.

The structure of a supercharged washing foam generator is shown in the figure:

The device of a foam generator with pressurized supply tank

Foaming begins already in the supply pipe, since due to the so-called. throttling effect, the pressure behind the mesh filter drops and air microbubbles are released from the mixture. This is not foam yet, but there are many embryos of it. Amateur designers usually do not install a foam concentrate nozzle, passing the mixture ready to foam directly through the bubbler. But in vain: a sharp drop in pressure behind the jet does not produce an aerosol, but a “foam sol” of tiny droplets of high-expansion foam. In the bubbler they “swell” with air, almost without losing their multiplicity, and thick, sticky, almost non-draining “Nivea for cars” goes into the hose.

Setting up a supercharged foam generator does not require qualifications:

• the compressor gearbox is set to a pressure from 4 bar (min.) to 6 bar (max.) depending on the required foam flow;
• the boost and adjustment valves are fully open;
• turn on the air supply and set the foam ratio using the valve settings (visually, based on its density and fluidity);
• the boost valve sets the foam flow rate;
• If necessary (rarely), I adjust the quality of the foam using the adjustment valve.

An ejection-type foam generator (in the next figure) is also connected to the compressor through a pressure reducer; A check valve in this installation is not necessary; the standard one in the compressor will suffice. The design of an ejection foam generator is similar to an injection one, only the nozzle is moved to a different location.

The device of a foam generator without pressurization of the supply tank

But setting it up is more complicated:

• shut-off valves are closed;
• The air control valve is opened approx. half;
• the foam concentrate control valve is closed;
• turn on the air, open the shut-off valves;
• by smoothly opening the foam concentrate control valve, achieve the appearance of foam from the nozzle nozzle (see below);
• Operating the control valves alternately or simultaneously to achieve the desired consistency and foam consumption. The adjustments are interdependent!

Note : if you need to wash the same car, operated under the same conditions, with the same shampoo, then after adjusting the foam, it is better to carefully remove the handles of the control valves so as not to disturb the adjustment.

Design Features

The supply tank of the injection foam generator must withstand a pressure of at least 8-9 bar. The purpose of the check valve is rather technological: when the foaming agent has been used up for approx. by 2/3, the compressor can be turned off, and the rest of the mixture will be produced under residual pressure, because its fluctuations within 30-35% do not significantly affect the foam parameters. The diameter of the hole in the jet washer is 1-3 mm and is selected for a specific shampoo; You can get a set of washers with holes of different diameters. Length L of the mixing chamber of the injection generator is 120-180 mm; ejection 220-350 mm. Channel diameter resp. 8-20 and 9-12 mm.

Device Upgrade

Refinement includes improving the functioning of the nozzle. The disadvantage of standard nozzles is that the water is supplied under low pressure, so proper mixing is not observed. Let's look at two ways to modify factory foam generators.

Replacing the nozzle

To upgrade, you will need to use a screw nut. You can find it in the computer system unit. This is the product that secures the motherboard. The advantage of a screw nut is that it is made of soft materials, so it will not be difficult to drill a hole in it. To do this you need to take a drill with a diameter of 1 mm. A hole is made in the middle of the nut. A cut is made at the end part so that it can be screwed in with a screwdriver. The resulting device should be screwed inside the nozzle.

Now you need to take a similar type of nut of a slightly larger size. A hole with a diameter of 2 mm is drilled in it. The nozzle is installed on the side that will be turned towards the nozzle. To do this, take a core from a gel pen, from which a part of at least 30 mm in length is cut off. A hole with a diameter of 4.6 mm is made on the nozzle in the upper part. Everything is connected with sealant. Test work can begin.

Parts and components

The critical components of the foam generators described here and below are:

1. passive bubbler;
2. mesh filter;
3. check valve;
4. spray nozzle.

Bubbler

Passive bubblers for washing foam generators are sold under the name foam tablets. Hobbyists, as a rule, make foam tablets themselves from a steel kitchen sponge (scraper, “brush”). But - no need.

A high-quality branded foam tablet is a putanka (emphasis on the first syllable) made of round stainless wire, see figure:

Foam tablet for foam generator

Firstly, steel sponge is not designed for long-term work under pressure in an active environment. Secondly, it (the steel sponge) has a lot of thin sharp edges. Active foam “pinches off” microparticles of solid metal from them. Not a bad abrasive, right? And - on sparkling paint. The car begins to lose its appearance after 3-10 washes, depending on the quality of its painting.

Net

Strainer:

1. begins foaming in the supercharged injection generator;
2. serves as an active bubbler in a double bubbling foam generator (see below);
3. can become the basis of a very good homemade passive bubbler, in no way inferior to the best branded one.

For the latter case, you will have to buy something, but quite inexpensively, in some hardware store ("Everything for the home", plumbing, etc.). There, however, they do not always know what it is. Often it’s just They put a price tag without the name of the product. So let’s take a closer look.

Unscrew the cap from the faucet spout of the kitchen sink or washbasin (arrow on item 1 in the figure below). This is done simply with your hand, if you hold the “gander” with the other. Examine what is unscrewed. Do you see the mesh (item 2)? Push it with your finger and the mesh filter will come out. Its lid can be removed if you pry it off with a toothpick, etc. in any of the side holes, arrow on pos. 3. The meshes are squeezed out with your finger in the same way (pos. 4).

Household tap strainer

Note : you might be surprised how much dirt there is! In such a case, the nets are cleaned with an old toothbrush under a weak stream of water. Signs of clogging - the stream from the tap jerks, breaks into drops early, and splashes.

Now let’s remember what to look for, or take it with us as a sample - to show it to a young, tolerant, politically correct, confident saleswoman. At home, we disassemble the “new, good” filter and cut off the stop from the cover (arrow on item 4). For what? 3-4 meshes are not enough for a foam generator. The missing ones can, firstly, be cut out from an old strainer from a Chinese teapot; stuff them as much as will fit. This thing is suitable for a filter, and instead of a foam tablet (installation diameters 20/18 mm) for a productive foam generator. The foam is a sight to behold - high-quality, thick, you could make snowballs out of it.

Secondly, you can supplement the filter with synthetic felt cut from a soft kitchen sponge (see figure). It is necessary to cut with a lack of thickness so as not to catch the adhesive layer. A filter with this addition is suitable for an active pneumatic bubbler and a passive one in a manual foam generator.

Valve and nozzle

Do-it-yourselfers install purchased reed valves in their foam generators or make them themselves “in the image and likeness” of standard ones. Which requires turned parts and some plumbing experience. And we will make a ball valve at home “on the knee”, that is, on the work table. Its throughput is lower, and its response delay is greater than that of a leaf valve, but we don’t need to turn a turbo drill, and the ball valve is very durable and reliable.

You will have to buy a bronze water tee for 1/4″ - 3/4″ (crosspiece, if the generator has a pressure gauge) with an external thread (type NNN), select a ball from a bearing of a suitable diameter and a piece of tube for it; drawings and proportions of a check valve for a homemade foam generator are given in the figure:

Ball valve drawing for foam generator

The assembly is done as follows:

1. in the tee/crosspiece, holes for stops are drilled in one pass;
2. one of the ends of the piece of tube for the valve seat is countersunk with a conventional twist drill;
3. the saddle is placed in the tee/crosspiece and placed on the table with the saddle down;
4. insert the ball and, with light blows of a hammer, drive it to the saddle through a hard wooden stick;
5. the seat is secured from the outside to prevent it from falling out with silicone glue; the connecting fitting will not allow it to be squeezed out under pressure;
6. place a stop, fix it with silicone or caulk it.

Note : a homemade ball valve may leak a little at first, but after 3-4 air starts/misfires, the ball will “beat” its seat until it is completely tight.

Drawings of the spray nozzle for the washing foam generator are given on the following. rice.:

Drawing of a spray nozzle for a foam generator

If the foam is simply supplied through a hose without a gun (which, of course, is inconvenient), instead of a threaded socket, a herringbone fitting is machined for the hose. It is not advisable to reduce the length of the nozzle, because it also serves as a “mint” stabilizer in the foam hose. Making a nozzle is quite complicated:

1. through channel D6 is drilled;
2. the threaded socket is turned out, the workpiece is turned to the shape from the outside;
3. From the right (according to the drawing) end of the workpiece, 2 D6 holes are drilled at an angle, converging in a V-shape at 27 mm from the end. This is a complex and responsible operation;
4. From the left end according to the drawing, channel D9 is drilled to a depth of 270. It is advisable to go through it with a reamer after drilling, because roughness in the channel strongly “hits” the foam expansion rate;
5. Excess material is removed from the right end with a thin narrow cutter. This is the most delicate operation;
6. The fit of the nozzle on the gun is checked and adjusted by grinding the left end, see fig.

Tank options

It is better to make an injection foam generator based on a powder fire extinguisher, and there is a pitfall here - its standard bubbler. The first powder fire extinguishers were plastic containers with a lid filled with self-foaming extinguishing powder when heated. Simple, cheap, but if it got on a hot metal surface, the powder could explode. In general, simple dry powder fire extinguishers have saved many more lives and property than they have caused harm; quite a few of them are still waiting in the wings to this day. But, of course, a possible explosion instead of extinguishing a fire is no good. Therefore, modern powder fire extinguishers (see figure on the right) are filled with microencapsulated fire extinguishing composition and pumped with an inert gas, which squeezes the powder through a steel sponge. The shells of the microgranules in it are destroyed, and the ready-made extinguishing mixture comes out. It’s complicated, a little expensive, the fire extinguisher needs to be checked periodically, like a carbon dioxide one, but an explosion is excluded.

So, the foam tablet enters the internal nest of the microgranules destructor. First, they naturally use a used-up fire extinguisher for the foam generator, and don’t buy the tablet. Why, it seems, if something that looks suitable already exists? But the fire extinguisher destructor is disposable; it will create dust with a steel abrasive even stronger than a kitchen sponge. Secondly, there is no aerosol chamber in front of the bubbler in the fire extinguisher, and without it high-expansion foam will not be produced, this is the first. However, this is “not fatal”; it is possible to modify a foam generator from a fire extinguisher to obtain high-expansion foam, see video:

Video: modifying a foam generator from a fire extinguisher

Note : for another version of a homemade foam generator from a fire extinguisher, see next. video clip:

Video: making a foam generator from a fire extinguisher

Options for the Beetle

A foam generator from a Zhuk type sprayer can be made with supercharging from a built-in pump or compressor. To wash a city car, 3-7 liters of foam concentrate are required. Garden “Beetles” are available in capacities from 5 to 10 liters, above in the figure:

Garden sprayers of the “Beetle” type and a foam generator from such a sprayer

To ensure that the foam “keeps its condition” and does not stagnate while the tank is being pumped up, you need to fill it with foaming agent no more than halfway (preferably 1/3). And in order to wash a large car with a small “Beetle”, you need to install a pipe in its tank to connect the air hose from the compressor (shown by the arrow below in the figure). If the compressor is homemade without a graduated gearbox and pressure gauge, then the pipe is needed with an internal inch thread. A tee with a check valve is screwed into it (see above). A pressure gauge is screwed onto the free arm of the tee; threaded joints are sealed with FUM tape. In order for the sprayer to be used for its intended purpose after modification, you will also need to buy a plug for the shoulder of the tee with a valve.

How does a foam generator work?

The operating principle of the foam generator is quite simple and is as follows:

1. A cleaning solution of water and an active substance, for example, car shampoo, is poured into the tank (cylinder).
2. A compressor is connected, which pumps air to create high pressure.
3. Under pressure, the solution p is squeezed into the valve of the nozzle (gun).
4. Passing through the nozzle, the product undergoes primary foaming. At this stage, the foam does not have sufficient resistance and is therefore not suitable for washing.
5. Next, the foamed liquid passes through a “foaming tablet” made of a metal hydrophobic mesh with a given mesh size and turns into finely dispersed dense foam, which is released by a gun in a given direction onto the car body.
6. It is possible to adjust the jet emission speed and expand the spray area.

At the exit from the foam concentrate, the stream is usually given a flat shape.
Its length can reach up to six meters. A powerful foam generator with a long hose and a convenient nozzle allows you to apply foam to hard-to-reach surfaces. What is important for the quality performance of a foam concentrate? When choosing equipment, take into account the compact size, weight of the complex, its maneuverability, and sufficient foam formation. The quality of car foam treatment depends not only on the effectiveness of the chosen cleaning agent and the quality of the foam of sufficient density, but also on the ease of use of the device. The durability of the equipment is ensured by high-quality materials. It is better to give preference to a foaming agent whose elements are made of stainless steel. The reliability of the assembly matters.

The foam tablet significantly influences the quality of the foam, since it is it that forms the persistent cleaning mass. This mesh filter wears out, becomes clogged with dirt, and also accumulates detergent chemicals that cement the mesh. If the quality of the foam decreases, the “tablet” is replaced.

If a new foam generator tablet does not change the situation for the better, it is recommended to completely disassemble the nozzle in order to clean the internal jets using the same compressor or strong water pressure.

The resource of the entire complex depends on the intensity and conditions of its operation. If its effectiveness has decreased, then before completely replacing the foam concentrate, preventive replacement of individual components is performed: fittings, gaskets in connections, etc.

Manual mini foam generator from a sprayer

“Beetles” are also produced as hand-held household ones. However, for a non-compressor mini-foam generator with double bubbling, any household sprayer of a similar design is suitable: an excess pressure of 1-2 bar, to which it can be pumped with a standard pump, is sufficient in this case.

To make a portable foam generator from a household sprayer, you first need to remove and disassemble the outlet valve of its air pump, on the left in the figure:

Making a foam generator from a household sprayer

There is almost always enough space in the valve nozzle to place a synthetic felt gasket at the air outlet (see above) and thus obtain a first-stage pneumatic bubbler; You may need to tighten the valve disc return spring a little. The primary bubbler is checked by immersing it in a jar of water: when you press the piston rod, air should come out into the water in a thick stream of small bubbles. You may need to add felt. Next, the standard sprayer is unscrewed, and the body of a medical syringe with a foam tablet (preferably branded wire or homemade mesh, see above) and 3-4 layers of synthetic felt from a kitchen sponge are pulled onto its nozzle. The felt pad is placed first along the foam path, on the right in Fig. That's all, you can refill and wash. Only if the sprayer is used for its intended purpose, the primary pneumatic bubbler will need to be removed before filling with fertilizers or pesticides, otherwise the active ingredients of the drugs may oxidize before they fly out.

Finally, note : for 2 options for turning a sprayer into a washing foam generator, see the video:

Briefly about the device

Before you start making your own foam concentrate, it’s worth thoroughly understanding what this device is! It is impossible to wash a car in a contactless way without a foam generator. The most important functions of this type of device are: the formation of foam of the density you need, and its uniform distribution over the entire surface of the car. This process goes like this: a stream of water passes through a tank containing washing liquid (which is used in foam generators), after which it is mixed with a stream of air that enters through a special hole. As a result of this, foam is formed, but it is still not suitable for use. In order to obtain foam of a certain density, it is fed at a very high speed onto a special foaming tablet, after which the substance of the required density comes out.

Manufacturing a functional and safe design

Before manufacturing begins, it is necessary to realize that the main dangerous factor during operation of the device will be high pressure. When assembling a foam generator with your own hands, you should not skimp on installation elements.

Requirements for foam generator capacity

It is more convenient to make a homemade foam generator from a container of 25 liters or more. This will be enough for a one-time wash. The main requirement for the cylinder will be to be made of stainless steel, or ordinary steel can be used provided it is treated with an anti-corrosion compound. Durable plastic is also actively used.

Additional conditions will be:

• pressure resistance up to 6 bar;

the presence of a measuring ruler to control the filling level of the container;

the presence of threaded holes for a sprayer and a pressure gauge.

Sprayer requirements

The design includes a foam sprayer. This element must be different from a similar sprayer type device. Such equipment is designed to produce an emulsion, which is inferior in cleaning efficiency.

A suitable nozzle for a car wash in a steam generator compares favorably with a simpler example:

• has a finer spray;

allows you to adjust the feed rate;

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provides savings in cleaning solution.

High pressure cleaning solution

It is impossible to create a foam generator with your own hands for a car wash without a pressure source. For normal operation of the equipment, the pressure created must be in the range from 4 to 6 atmospheres.

When completing the installation, the compressor will be the most expensive element. If you purchase a used sample, you should discard the sample with signs of wear. In this case, a compact unit for inflating wheels will also not cope with the job.

How to make your device more perfect

The practice of building homemade foam generators allows us to highlight new directions for their modernization. And if the main drawings remain the same, then individual elements can be easily replaced.

For example, a foaming element based on wire or fishing line can be easily replaced with a piece of foam sponge. It is enough to secure it well in the wire tube. Instead of a fire extinguisher, a propane tank is successfully used.

Alternative reservoir

An alternative option for making a manual foam generator would be an ordinary plastic canister. In this case, it is possible to use the neck cover to secure both fittings.

We attach a plastic tube to one fitting from the inside. Inside, due to dense packing with fishing line, we prepare a foaming device. We attach a hose with a sprayer at the end to the outside.

We leave the second fitting free to connect the compressor. This is how you prepare the simplest touchless car wash with your own hands.

Device Features

It doesn’t matter whether you buy an Italian foam generator or order one from China, structurally they all look about the same.

The design includes:

• gun;
• mixer;
• balloon.

A special nozzle, as well as a foam-creating tablet, ensure that this mixture is supplied under high pressure. As a result, the car is quickly coated with a layer that removes dirt.

Such washing cannot be called completely contactless. If you want results, you will also have to work with sponges or brushes.

An important characteristic on which the operation and the best indicator of efficiency depends is the volume of the tank. Usually they are made for 25-100 liters. The compressed air supplied from the cylinder should have a pressure of 5-6 bar. At the outlet, the manual foam generator has a special regulator. It allows you to control the pressure using a built-in pressure gauge.

Sprayer or generator?

This is where a very important point arises. If you need a mini-wash, I advise you to choose a foam generator. Although many sellers offer to buy a sprayer for car washing. Some even pass off an ordinary sprayer as a supposedly highly efficient foam generator.

In some cases, a universal sprayer can perform well. But it is inferior to foam because it is not able to create the same persistent foam. At the exit you get a regular emulsion, the efficiency of which is much lower.

Therefore, I will teach you to distinguish sprayers from generators.

• the sprayer circuit does not provide for the presence of a regulator to control the quality of the mixture;
• The sprayer has a larger nozzle at the outlet than the foam sprayer.

These distinctive characteristics are enough to make the right purchase.

If we talk specifically about manufacturers, then you should pay attention to the following brands:

• Karcher;
• Monsoon;
• Calm (Stihl);
• Huter (Huter);
• Bosch;
• Elitech;
• Procar;
• Idrobase;
• Interskol;
• Champion;
• Patriot.

Go to Aliexpress, read reviews, explore different stores. The Internet works 24 hours a day, so information about a particular model can always be found out.