Heating and water supply pipes often make strange sounds, but they are not always paid attention to. Clicks, knocks, squelching - all these are signs of water hammer. And what is water hammer in a water supply system, the causes and consequences of the phenomenon - it’s worth talking about this in more detail. And also learn how to prevent trouble.
Water hammer is a short-term powerful increase in the pressure of the liquid that circulates in the pipes. The pressure increases due to changes in flow speed.
The sign of the pressure change affects the type of water hammer:
- positive - in which the pressure increases due to the sudden closure of the valve or the activation of the pumping unit;
- negative - in which the pressure increases due to the pump stopping.
According to the laws of physics, even when the tap is suddenly closed, the water continues to move. Only the flow closest to the valve stops; the remaining layers continue to flow. The collision of the stopped and moving layers causes an increase in pressure. If you imagine that the entrance to a moving crowd has been abruptly closed, then the first rows have already stopped - the next ones bump into them, continuing to walk, the result is a crush. Water also acts, causing water hammer.
The pressure increases instantly, the level increases by several tens of atmospheres. The consequences cannot be avoided.
Water hammer theory
The occurrence of the phenomenon is possible only due to the lack of compensation for pressure drops. A surge in one place causes a force to spread throughout the entire length of the pipeline. If there is a weak point in the system, the material may become deformed or fail completely, creating a hole in the system.
The effect was first discovered at the end of the 19th century by Russian scientist N.E. Zhukovsky. He also derived a formula by which to calculate the period of time required to close the tap in order to avoid unpleasant consequences. The formula looks like this: Dp = p(u0-u1), where:
- Dp – pressure increase in N/m2;
- p – liquid density in kg/m3;
- u0, u1 are the average water speed in the pipeline before and after closing the taps.
To know how to prove water hammer in a water supply system, you need to know the diameter and material of the pipe, as well as the degree of compressibility of water. All calculations are carried out after establishing the water density parameter. It differs in the amount of dissolved salts. The speed of propagation of water hammer is determined using the formula c = 2L/T, where:
- c – designation of shock wave speed;
- L – pipeline length;
- T – time.
The simplicity of the formula allows you to quickly determine the speed of propagation of the impact, which, in essence, is a wave with oscillations of a given frequency. Now let’s talk about how to find out fluctuations per unit of time.
For this, the formula M = 2L/a is useful, where:
- M – duration of the oscillation cycle;
- L – pipeline length;
- a – wave speed in m/s.
To simplify all calculations, knowledge of the shock wave velocity upon impact for pipes made of the most popular materials will allow:
- steel = 900-1300 m/s;
- cast iron = 1000-1200 m/s;
- plastic = 300-500 m/s.
Now you need to substitute the values into the formula and calculate the vibration frequency of the water hammer on a section of a water pipeline of a given length. The theory of water hammer will help to quickly prove the occurrence of the phenomenon and prevent possible risks when planning the construction of a house or the replacement of a plumbing or heating system.
Causes of water hammer
The most important reason is the sudden closure of the shut-off valves. If the water flows in a thin stream, the risk is minimal, but when the tap is opened/closed abruptly, the danger increases to the maximum.
Why else does water hammer occur in the water supply system:
- When powerful pumps are turned on abruptly. Occurs when the power supply to facilities equipped with powerful pumping stations is unstable.
- If there are air pockets in the water supply or heating system. Therefore, before putting closed systems with a liquid carrier into operation, the air must first be removed.
Today, water hammer is considered the most common factor in the failure of water supply systems. This is due to the advent of new shut-off valves that do not require long turns of the valve (taucet) to open/close water.
Worth knowing! It is especially dangerous to shut off powerful jets of water - even with a working water supply system, this will sooner or later lead to water hammer.
Possible consequences of water hammer and its dangers
You can recognize the signs of the phenomenon by extraneous sounds in the system: clicks, knocks, collapses. Visual signs will also help: leaking taps, mixers, crimp fittings with rubber gaskets.
When the water supply system is subjected to frequent water hammer, even of weak force, gaskets and seals are squeezed out first. Violation of the tightness of the system can lead to the appearance of areas of deformation and rupture of pipes.
As a result of increased pressure, the water supply is disrupted. But this is not the only trouble. If a water hammer leads to a complete rupture of a pipe, for example, in an apartment building, the entire building is left without water. The flow of liquid spoils the property of the apartment owners, and the neighbors on the lower floors are flooded. As a result, work on the repair and restoration of several residential properties took place.
Water hammer in a hot water supply system threatens, in addition to permanent damage to property, burns. Danger occurs when the heating system depressurizes, where the medium maintains a temperature of +70C and is constantly under pressure. A rupture of a battery or pipeline during the winter heating season will damage the system. Frosts will complete the destructive work - the pipeline will have to be replaced.
Methods to combat and prevent water hammer in the system
Pressure surges in systems cause up to 60% of all pipeline accidents. Old and long pipelines are particularly at risk. Worn out systems have many weak points where a minimal surge in water pressure will cause a rupture. And one more fact - the longer and straighter the pipe, the stronger the water hammer will be. This is due to the fact that more water is placed in long pipes, which means that the mass of the carrier is large and can cause a strong pressure drop.
Advice! If a private house is equipped with ball valves, the temptation to quickly turn it on and off is great. One turn and the tap is closed. This is strictly forbidden. The result of a sudden stop of the fluid will soon manifest itself in the squeezing out of the rubber seals, and then in the rupture of the system.
Is there protection against water hammer in the water supply system of an apartment or private building? Yes. The first and most important thing is not to test the system’s strength with sudden pressure switches. Let's look at a few more options on how to avoid water hammer in the water supply system.
Smooth closing of the tap
The easiest way to prevent trouble. The valve must be closed smoothly, without jerking. If the shut-off valve is tight, it is permissible to move the handle with small jerks. Action applies to both household and industrial taps.
There will still be a water hammer when closing, but one powerful one is broken into several low-power ones. The energy impact on the pipeline during a single sudden movement is divided into several small ones, while pressure drops have time to be compensated, thereby reducing the risk of system failure.
Shock absorbing devices
Shock absorbers are used to protect pipelines with thermostats. These are flexible parts of the pipe that replace the rigid part before the thermostat valve mounting point. Material for the shock-absorbing device: rubber with high heat resistance properties or reinforced plastic. The ability to stretch and absorb the force of increased pressure helps to avoid water hammer.
The principle is simple: as pressure increases, the soft part of the pipe expands in diameter, acting as a damper, thus reducing the pressure in front of the closed valve. To prevent water hammer, a pipe section of 20-30 cm is enough; if the system is very long, the elastic shock-absorbing element can be increased to 40 cm.
Bypass surgery
Manual modification of the thermal valves will be required. Knowledge of design features will be useful, otherwise the element can be damaged. The shunt is a thin tube with a diameter of 0.2-0.4 mm, which is inserted into the valve in the direction of fluid movement. The shunt does not affect the functionality of the system during operation, but during pressure surges it releases it into the pipeline behind the valve.
Advice! Shunting will help if the problem is how to eliminate water hammer in the water supply system of new pipelines. Dilapidated pipes with corrosion are not shunted; rust quickly clogs the hole. In this case, instead of installing a tube, a drilled hole of the required diameter is enough.
Safety thermostats
These are special devices that are additionally equipped with protection against water hammer. The protection looks like a spring mounted at the connection point between the valve and the thermal head. The protection property is described in the technical documentation.
The principle of operation is simple - when pressure surges, the spring stretches, which prevents the valve from closing tightly. Excess pressure is also released into the pipe section behind the valve. When the pressure normalizes, the valve closes.
Advice! Installation of thermostats that are protected against water hammer must be carried out in the direction indicated by the arrow on the housing.
Safety valves
A simple water hammer safety valve operates as a pressure relief system. A safety valve is installed in areas most susceptible to water hammer. The devices can operate independently or receive controller commands.
In the latter case, the controller must control the entire operation of the system and have data on pressure along the entire length of the pipeline. When the pressure level in the valve installation area increases, the device opens and discharges excess water to the outside. As soon as the pressure decreases, the valve closes and returns to its original position.
Compensators
A water hammer compensator is used in internal water supply and heating systems. The device looks like a reservoir divided into two parts by a rubber membrane. The lower part is connected to the water supply, so there is always water there. At the top there is air under pressure. If the compensator is an element of the heating system, it is installed in areas with a high risk of water hammer.
Operating principle: as pressure increases, the liquid carrier presses on the battery membrane, the air is compressed, and the membrane moves. Increasing the volume of the reservoir helps compensate for excess pressure. As soon as the shock is eliminated, the membrane returns to its original position.
Automatic control devices
The units are used in systems equipped with pumps. The more powerful the pump, the stronger the water hammer will be. The level of pressure increase is determined by the speed of the motor; when voltage is applied, the electric drive starts instantly. The only way to avoid water hammer is to make the increase in speed smooth. The use of automatic control devices makes it possible to influence frequency converters and soft start devices.
Changing the frequency, as well as gradually starting the engine into operation, minimizes the risk of water hammer. Frequency converters also regulate pump performance while maintaining optimal equipment operation.
Knowing what water hammer is, the consequences of the phenomenon, and how to eliminate the problem, it would be useful to modernize the pipeline or at least avoid abruptly closing valves and taps. The devices are inexpensive, last a long time and will extend the life of the entire plumbing and heating system.
According to statistics, about 60% of all destructions (breaks) of pipelines occur due to water hammer, which is a short-term, sharp and significant surge in pressure in a pipe resulting from a sudden change in the speed of fluid flow. The usual signs that accompany this serious trouble are clicks, knocking and other noise that occurs in communications that supply us with water and heat. Many people don’t even pay attention to them, but water hammer in the water supply system leads to equipment damage, cracks, and split pipes. Strict adherence to the rules for operating pipelines and modernization of utility networks will help prevent an emergency.
Nature of water hammer, possible causes
Owners of private houses with poorly arranged engineering communications often hear a characteristic clicking and knocking sound, which indicate that a short-term sharp increase in pressure has occurred in a closed system as a result of a sudden cessation of fluid movement along the circuit or a sudden resumption of its circulation.
When a fluid flow moving at a certain speed collides with an obstacle (air or shut-off valves), its speed does not change immediately, but the volume quickly increases, the pressure increases and sometimes reaches 10 atmospheres or more. If the “surplus” has nowhere to go, then there is a risk of pipe rupture.
Possible causes of water hammer:
- starting, stopping and breakdown of the pump or its emergency shutdown;
- air in the system;
- a sudden stop in the flow of liquid in the circuit, caused by the rapid opening and closing of shut-off valves: taps, valves, etc.
The last reason is the most typical since valve taps, with their smooth running, were replaced by more modern and “sharp” ball counterparts.
If air is not removed from the system, then when the ball valve is opened, a collision of the air mass and a practically incompressible liquid occurs, as a result the pressure value can increase to several tens of atmospheres. Such a regular “strength test” has a very negative impact on the condition of the system as a whole and the pipes in particular; the outcome is not difficult to predict.
Heating system congestion is a common problem. You will learn how to bleed air from batteries in our article:.
Unpleasant consequences and methods of protection against water hammer
A barrier that suddenly appears in the path of liquid flow creates pressure, which, theoretically, can grow indefinitely. In this case, the rigid elements of the system experience severe loads and gradually or abruptly collapse.
The consequences of water hammer can be disastrous, especially for old pipelines
Accidents caused by water hammer in the heating system are accompanied by a number of characteristic troubles:
- destruction of pipelines and equipment of heating networks;
- rupture of heating devices;
- burn injuries;
- long-term interruption of heat and water supply;
- flooding of the home and damage to property.
Long pipelines, for example, heated floors, are most vulnerable to water hammer. To protect the “underground” system, it is equipped with a thermostatic valve, the installation of which must be entrusted to good specialists, otherwise another risk factor will appear in the system.
Proper protection of heating or water supply systems from water hammer is aimed at reducing their intensity and neutralizing the effects of excess pressure.
No sudden movements
The easiest way to protect yourself from water hammer is to smoothly turn on and off the shut-off valves. This nuance is clearly stated in the standards for the operation of centralized water supply facilities and heating networks. The rule can be extended to autonomous networks without any reservations.
The bottom line is that smooth switching on and off extends the process of increasing pressure over time. The energy of the water hammer does not act with all its force at once, but is distributed over several time periods. At the same time, although the total impact force remains the same, the power decreases.
Option using automation
The smooth start and stop of the engineering system can be completely entrusted to automation. Pumps with automatic speed control of the electric motor smoothly increase the pressure in the pipes after starting, and also systematically operate in the reverse order. The software equipment not only monitors pressure changes, but also automatically adjusts the pressure.
The best effect comes from a comprehensive modernization of the system, which will help prevent water hammer in the pipes. It includes a number of different activities.
Water hammer compensators, dampers, hydraulic accumulators
An important element in heating and water supply systems is a water hammer compensator (aka damper, aka) - a device that performs three important tasks at once: accumulates (accumulates) liquid; accepts excess fluid from the system, thereby helping to reduce pressure in it; Accordingly, it helps to dampen water hammer if it occurs.
The water hammer compensator (damper) is installed in the most “dangerous” places
The compensator is a sealed steel tank with an elastic membrane and a built-in air valve. The volume can be either completely insignificant or quite large.
Interesting! In Europe, if a hydraulic compensator is not installed in the network, a warranty for household appliances, for example, a washing machine, boiler or dishwasher, is not issued.
To protect the pumping station in the event of a sudden stop of the pump, for example, a special diaphragm-type water hammer protection valve with a rigid seal is used. It is operated by fluid pressure and has a very useful quick pressure release feature. Install it after the check valve, at the outlet from the pipeline, next to the pump.
The valve is a reliable safety device in systems under pressure.
Installation of a shock-absorbing device
Installing a shock-absorbing device (plastic or heat-resistant rubber pipe) in the direction of fluid circulation, in front of the thermostat, is an effective method of protection. The elastic material spontaneously absorbs the energy of water hammer. A sufficient length is 20-30 cm; for a very long pipeline, the shock absorber can be increased by 10 cm.
Bypass surgery at home
Anyone who is familiar with thermostat design can install a shunt with a clearance of 0.4 mm in the thermostatic valve or simply make a hole of the same diameter. Under normal operating conditions, such an innovation will not affect the system in any way, but during overloads it will smoothly reduce the pressure.
Important! Shunting as a method of protection against water hammer is applicable only to autonomous networks with new pipes. Sludge and rust from the central lines make it completely ineffective.
Thermostat with super protection
Sometimes a thermostat with special protection against water hammer is used. Such devices have a spring mechanism installed between the valve and the thermal head. If there is excess pressure, the spring is triggered and does not allow the valve to close completely; as soon as the power of the water hammer decreases, the valve closes smoothly. Install such a thermostat strictly in the direction of the arrow on the body.
Water hammer in water and heat supply systems is a fairly common and dangerous phenomenon, but there are many ways in which you can neutralize the unpleasant consequences of this phenomenon and extend the life of household appliances and pipes.
The cause of water hammer in the water supply system is the property of water – its incompressibility. The water flow from the kitchen tap can be turned off with a quick turn of the handle. Resisting against an obstacle, the water creates an elastic reverse force. In this case, the water has nowhere to go, since the pipe is sealed. Its energy collides with the inertial flow of water. In such a collision, water hammer in a water supply system is determined by the fact that the energy of the water flow cannot be absorbed by its compression. In small pipelines such processes are insignificant.
This phenomenon is noticeably manifested at significant water velocities in pipes, a strong pipeline of large diameter and a sudden closure of the passage in a certain section of the pipe. Water hammer in systems can be reduced by using elastic materials for pipes or by installing special compensators. Such impacts can smooth out air pockets trapped in the system. But in any case, the force of the push will remain unchanged, except that its effect will decrease.
This is sufficient to prevent damage to the piping system. Only the principle of smoothing out a strong impact of water is the basis of many protective structures and equipment.
The main way to prevent water hammer is to reduce the closing speed of the water flow, as well as ways to reduce the pressure in the water supply system. For such purposes, valves with an extended stem are used. This allows you to slow down the process of shutting off the water pressure. But similar equipment requires an increase in the bore diameter of the pipe system.
Water hammer can be prevented by upgrading the pressure circuit and altering it. One of the solution methods was to connect an element made of an elastic material - metal-plastic or plastic - to a rigid pipe system. To create the required result, about 400 mm of this material is needed. Also, a special “U”-shaped compensator is installed on a straight section of the pipe, which also reduces the high-speed flow of water. In a hot water system, a heated towel rail can play a similar role.
The most progressive method of protection is a check valve in the water supply system, which allows a certain volume of water to pass through during a strong and sudden increase in pressure. Due to this, the load on the equipment and material of the pipeline system is reduced. The important factor is to adjust the function of this valve when it begins to function. With a very large opening characteristic, water hammer is very difficult to prevent.
Features of protective devices
In local modern water supply systems for country houses, protection against water hammer is applied to hydraulic accumulators of various types and devices. Typically, such containers are already included in the pump station kit. The hydraulic accumulator itself is most often made in the form of a tank with a volume of more than 30 liters. Inside, it is divided by a durable rubber membrane into two parts - water and air.
Water is periodically pumped into the first half under high pressure. Air is pumped into the other half at a given pressure. In this case, hydraulic shocks in the water supply system are also discharged into this tank. After the water pressure returns to normal, the elastic partition squeezes the water that deforms it back into the pipelines.
In practice, it becomes clear that the use of only a hydraulic accumulator is quite effective protection against water hammer in a pressure water supply system.
Video: Example of water hammer occurrence
If you often hear clicks and knocks in your water pipes, this is most likely caused by water hammer in the water supply system when you close the taps. The phenomenon is very common, and often leads to partial or complete failure of the system.
Being left without water for some time is not the biggest problem. It’s worse if a breakthrough happens in the absence of the owners, causing a flood in yours and the apartments below. Therefore, every homeowner should know why water hammer occurs, what it is and how to prevent it.
The nature of water hammer
First, let's figure out what water hammer is. It's simple: this is a sharp jump in water pressure in the pipes in one direction or another.
- When the pressure rises sharply when the pump is turned on or the tap is turned off, a positive hydraulic shock first occurs, since the water, by inertia, continues to flow at the same speed, but encounters a sudden obstacle in its path. In this case, in the area directly near the obstacle (for example, shut-off valves (see)), excess pressure is formed on the pipe walls. The water has nowhere to go; it compresses poorly, so the walls of the pipe stretch.
- When faced with an obstacle, the water stream is thrown back and collides with a wave that is still flowing towards. Again, this puts pressure on the walls of the sealed pipeline.
- With a sharp outflow of water mass from the obstacle, an area of low pressure is formed next to it, in which the walls of the pipe are now compressed. This is negative water hammer.
The shock wave does not subside immediately; it rolls in and retreats several times with decreasing strength and amplitude. All this happens in a fraction of a second, during which the pipes alternately experience positive and negative loads.
There are other reasons that cause water hammer. These are air pockets in the pipeline, sharp turns or connections of pipes of different diameters, sudden pump starts. Any obstacle to the high-speed flow of liquid changes its volume and, as a result, pressure.
Consequences and ways to prevent water hammer
Now let's look at what frequent water hammer can cause in a home plumbing system, how to determine what it is, and how to eliminate it.
What can a sharp increase in pressure in pipes lead to?
Let's start with the fact that the first sign of water hammer is noise in the system: knocking, clicking, dull blows. They can also be identified by visual signs. These are, first of all, flowing taps and mixers, as well as crimp fittings and connectors with rubber gaskets.
When water hammer impacts the water supply of a home with sufficient force, these gaskets and seals are the first to be squeezed out. The tightness of the system is broken.
For reference. Pressure surges can also damage water meters, pressure gauges and other control and measuring instruments.
But the most unpleasant thing is a pipeline rupture. It is not afraid of weak shocks, but regular exposure to powerful shocks can lead to depressurization of even a new water supply system.
Pipe rupture due to water hammer
In a word, such phenomena seriously affect the integrity of pipelines and their trouble-free service life. Sometimes we create problems for ourselves with our own hands, entrusting the installation of water supply to unqualified specialists, or doing it ourselves without knowledge and experience.
Pay attention! The result may be flooding of the apartment, damage to furniture and household appliances, and serious costs for restoring the water supply system. And sometimes serious injuries and burns occur if a heating pipe or hot water supply breaks.
What to do to eliminate water hammer and its consequences
Protection against water hammer in an apartment's water supply system can be done in different ways. But the first thing that needs to be done is to conduct an audit of the entire system to detect leaks, weak points and, in general, the age and suitability of the pipeline for operation.
It is better to completely replace old pipes with new plastic ones with welded joints. This is the most reliable and durable option.
Advice. If you install a system of pipes with a larger diameter than before, this will significantly reduce the force of water hammer by reducing the flow rate.
Now we suggest exploring several ways to eliminate this phenomenon or reduce its impact on your plumbing system. Some of them are useful in apartments, others in country houses with autonomous supply. But most are universal.
Let's start with them:
- Replacing taps. Most faucets in our homes have a ball design, which allows you to turn off the water in one motion. This is very convenient for the consumer, but not very good for the system, because it is the sudden appearance of an obstacle in the flow path that leads to a pressure surge. If you replace ball valves with valve ones, the pressure in the pipeline when they are closed will change gradually, and over a longer period of time.
- Installation of shock absorbers. This can be a special rubber vibration insert, or an elastic hose made of plastic or rubber, embedded in the pipeline in one of the sections. When a shock wave occurs, the shock absorbers stretch or compress depending on whether the pressure in the system has increased or decreased, and instantly dampen it. Their elastic walls do not deform, unlike the rigid walls of pipes.
- Installation of expansion joints. These are spring parts screwed into the pipeline that absorb excess pressure and reduce vibration and noise. A steel spring located inside the air chamber is connected to a plastic disk. When the pressure in the pipe increases, the disk puts pressure on the spring, causing it to compress and make room to absorb the shock wave.
It is worth dwelling in more detail on the design of such compensators and the rules for their installation.
In the following picture you can see the structure of the part in section, where:
- 1 – housing cover;
- 2 – spring;
- 3 – sealing ring;
- 4 – plastic disk;
- 5 – lower part of the body;
- 6 – clamping ring;
- 7 – seal.
Water hammer compensator in internal water supply systems FAR HP 1/2″
The diagrams above show examples of correct installation of expansion joints. They can be mounted horizontally or vertically, on cold and hot water collectors, or on any section of the pipeline leading to the end point of water consumption.
The main thing is not to allow water to stagnate at the entrance to the compensator, otherwise bacteria may begin to multiply in the system. For this reason, the instructions do not allow its installation at the top of the riser.
As for the technical characteristics, for this particular device they are as follows:
These are the parameters by which the device is selected. They may vary.
If your home is supplied with water from an autonomous source using pumping equipment, the following methods can be used to prevent water hammer:
- Installing a hydraulic accumulator(cm. ). It is part of pumping stations and is a tank with a rubber membrane dividing it into two chambers - air and water. During a water hammer, excess water will be discharged into this tank until the pressure in the system normalizes.
- Usage, automatically regulating its operation and ensuring smooth start and stop. In this case, a sharp increase in pressure, which leads to water hammer, is excluded.
These are the most common methods that allow you to reliably protect the indoor water supply system from deformation and destruction.
Conclusion
According to statistics, more than half of pipeline accidents are not due to corrosion or fatigue of materials. They are caused by water hammer in the water supply system. But, as you have already seen, they can be completely avoided if you immediately install the system according to all the rules and equip it with special devices that dampen the shock wave.
What can happen if this is not done, watch the video in this article.
The phenomenon of water hammer has long attracted the attention of many scientists and scientists.
The scientist N.E. showed particular interest in this issue at one time. Zhukovsky. His work, which talks about the nature of water hammer, is considered to be a classic. With the beginning of the introduction of electronic computers, there was a clear progress in the methodology for calculating water hammer. The calculation methodology has improved significantly.
Each of us is familiar with the occasional clicks and knocks in the heating system pipes. This may be due to the fact that power outages are becoming more frequent. Therefore, special attention must be paid to the issue of protection against water hammer.
Basically, people do not attach much importance to this and do not see serious threats. However, the consequences of this fact can be disastrous.
Water hammer in a water supply system can lead to damage and excavation of equipment. In addition, cracks may form in the pipeline. To avoid emergency situations, it is enough to follow simple rules for operating and upgrading the utility network.
Main causes
Causes
When a sharp, but powerful and short-lived increase in pressure occurs in the water supply system, then characteristic knocks and clicks occur in the pipes.
This is a consequence of the fact that the liquid circulating along the circuit suddenly stops and it slows down.
There are several reasons that lead to water hammer. Let's look at them in more detail:
- In the event of a breakdown of the pumping unit or its emergency shutdown;
- When no air is removed from the circuit. Before turning on the system and filling it with liquid, the air must be released through special taps;
- When valves blocking the circulating flow suddenly close.
The last reason is considered the most common. This is due to the advent of ball valves. When the fluid in the circuit was turned off or started, the old devices provided smooth flow and shut-off.
This was done by rhythmically unwinding the crane bottles. Screw valves are considered safer, since they do not allow pressure to rise above a critical norm.
Watch a video about the causes of water hammer and all the processes occurring at this time in the pipes:
The same thing happens in the circuit if air is not removed from it before switching on. The ball device opens and, thus, a collision of the launched liquid with the air flow occurs.
In this case, the air can be compared to a pneumatic shock absorber. Therefore, if you hear pops or clicks in your communication system, be sure to pay attention to it.
Otherwise, it may happen that your water supply system simply cannot withstand the pressure, since its level can increase to several tens of atmospheres.
Damper as a method of protection
When a strong stream of water moves at high speed through a communication system, a barrier appears in its path, into which it crashes. Either an air column or a shut-off valve can act as an obstacle.
When it collides with air, the liquid contracts. The pipes, in turn, also stretch a little, which can lead to negative consequences.
When did clicks appear in the pipelines?
If you often hear clicks and knocks in your home, this means that your engineering communications are organized completely illiterately.
This occurs because large pipes are mated to pipes that are much smaller in diameter.
Thus, when a liquid circulates along a circuit at a certain speed, an obstacle appears in its path, against which it rests.
The speed does not change, but the unloading slows down and the volume of liquid increases, as a result of which the pressure increases.
At this point, water should be unloaded according to different registers. If this does not happen, then high pressure can lead to a breakthrough.
What will happen to the system after a water hammer?
Consequences of water hammer - rupture of radiators
As you already understood, a barrier encountered in the path of a moving fluid creates pressure.
In fact, it does not have certain critical values. A few tens of atmospheres can turn into a much larger value.
The inertia of water, constantly affecting the communication system, can lead to the destruction of rigid equipment parts, threaded connections and the pipeline as a whole.
Water hammer causes the most trouble to long pipelines. For example, a “warm floor” has long pipes.
To prevent water hammer from occurring in the system, it is necessary to attach a thermostatic valve to the “underfloor” heating circuit.
This part performs the function of a regulating device. However, it will only protect your floor if it is installed correctly. If the installation is carried out incorrectly, the thermostatic valve will only create an extraordinary threat.
The thermostatic valve is installed. When it overlaps, the water continues to move by inertia for a certain time.
After the valve there is a section of the circuit in which a vacuum occurs. However, the pressure difference in it does not go beyond one atmosphere. Changes do not harm the pipeline, because the equipment standards are 4 atmospheres. The flow movement is also blocked by a valve installed at the outlet of the system.
Watch a short video that clearly and schematically, using the example of a rubber tube and a watering can, will show what happens in pipes with air during a water hammer:
When a liquid collides with a barrier, the next portion of water presses on it. Thus, stretching, breaking and collapse of the pipeline walls occurs. The pressure is 10 and sometimes more atmospheres.
In order to protect the pipeline from one-time or periodic water hammer, it is necessary to neutralize their actions or reduce their force.
“Smooth overlap” protection method
According to heating network operating standards, the system must be turned on and off smoothly.
These rules are developed not only for industrial suppliers, but also for individual users. If turning off and on is carried out smoothly, then a delay in the time of the water hammer occurs.
Thus, the effect of water hammer energy in the barrier zone is not short-term.
There is a redistribution of energy over several periods of time. As a result, the impact power is not so strong.
Conclusion: To protect your pipeline from damage and destruction, you need to smoothly increase and decrease the pressure, speed and volume of the coolant.
Protection method "reconstruction"
In order to avoid water hammer, it is necessary to adhere to certain rules for the reconstruction of systems:
- Replace the rigid pipe in front of the thermostat with a piece of pipe made of flexible plastic or reinforced heat-resistant rubber.
These materials tend to stretch, so they will independently reduce the energy of hydraulic shock in the event of high pressure.
For the shock absorber you will need an elastic pipe approximately 20-30 cm long. If the pipeline is very long, then the pipe for the shock absorber must be taken another 10 cm longer.
- Shunt with a clearance of up to 0.4 mm in a thermostatic valve.
A narrow tube with a cross-section from 0.2 mm to 0.4 mm is inserted into the thermostat on the side of liquid movement. You can make a hole of a given diameter yourself. If the system is operating normally, then the shunt does not affect its functioning in any way.
If the pressure rises, it is able to smoothly reduce the volume exceeding the critical norm. Of course, you can only implement this method if you have a good understanding of the thermostat design. Otherwise, it is not recommended to take on this matter.
Remember: The bypass method is used only in autonomous networks where new pipelines made of high-quality materials are installed. Central city communications have a lot of rust and sediment. All this will lead to rapid clogging of the hole.
- Thermostat with special protection.
These devices have special springs that are located between the valve and the thermal head. The spring is triggered the moment the pressure rises. Thus, it prevents the valve from closing completely.
When the force of the water hammer decreases, the valve smoothly closes on its own. To correctly install thermostats with a safety device, you need to pay attention to where the arrow on their body is pointing. The mount must be carried out strictly following the direction of the arrow.
It is worth paying attention to the fact that not all thermostat models have means of protection against water hammer. You can find out whether your device is equipped with this function by reading the technical documentation that came with the product.
Protection method “centrifugal pumps”
Centrifugal pump
In order to smoothly start and stop the engineering system, it is necessary to use centrifugal pumps that have automatic adjustment.
With the help of automation, there is a smooth increase in the speed of the electric motors of the pumping equipment. In addition, the pressure in the pipes also rises systematically after start-up. The same mechanism of action is typical for the reverse order.
The pumps are programmed in such a way that they are able to independently monitor pressure changes occurring in utility networks. Pressure parameters are adjusted automatically.
The nature of the occurrence of water hammer is not so difficult to understand. The action occurs in two cases:
- When the rules for using communications are not followed;
- When networks are poorly designed.
If you do not pay attention to clicks and unpleasant noise, then very unpleasant consequences await household members.
It would be much wiser to understand the causes of noise effects and eliminate them than to subsequently repair a pipeline system that could not withstand powerful pressure.
