In this article, we will learn all about water hammer arrestors along with construction, working, installation, etc., to have the basic concept.
Let’s explore!
What are Water Hammer Arrestors?
Water Hammer Arrestors Basics
Water hammer arrestors are also called hydro-pneumatic devices. They function as shock absorbers and reduce the effects of water hammers to a greater extent. Water produces momentum when it flows fast through pipes.
- Sometimes the valve closes quickly and prevents the water from flowing. As a consequence of this, the momentum strikes the pipe heavily.
- The arrestors prevent this condition by providing a cushion of air that absorbs the momentum.
- They need to be installed in areas where faucets and valves are creating noise.
- The installation usually requires cutting pipes, inserting tees, and then installing water hammer arrestors.
In the past, water hammer arrestors were based on air chambers (pipes with capped pieces) filled with air and vertically mounted. Air is soluble in water.
- With increasing time, the air would get absorbed into the water, causing flooding inside the air chambers.
- Once flooded, they weren’t capable of absorbing pressure waves.
- These older designs based on air chambers need maintenance to drain the water and restore the actual function.
- This maintenance is very expensive if performed more frequently.
Moreover, the air chambers were also of random lengths. They were short in length (most probably up to 18 inches). It is also difficult to perform in areas where the water supply cannot be kept closed for longer and more often.
Later on, in the 1970s, they were replaced by maintenance-free arrestors. They worked based on the expansion and contraction of bellows to absorb the shocks. It prevented air and water interference.
These designs, after some years, were replaced by water hammer arrestors based on a copper pipe chamber. This pipe has a piston inside. It moves up and down in response to pressure changes. Just like the bellows, they are also maintenance-free.
Normally, it’s thought that water hammers cause loud sounds. They may not be causing any rattling sounds in some cases, but the water supply lines are still damaged.
What is a Water Hammer Arrestor? Definition
Water hammer arrestors are defined as gadgets that help absorb the shocks when the flow of water in the piping system is suddenly disrupted due to the swift closing of shutoff valves.
- Water hammers create loud and banging sounds that indicate damage to pipe walls, flow meters, or pressure sensors.
- As the name indicates, water hammer arrestors are devices designed especially by plumbing and drainage industries to eliminate water hammers.
Construction of Water Hammer Arrestors
The construction of modern water hammer arrestors is more like the ones with air chambers. However, there are slight differences.
- The construction is such that it contains a waterproof air bladder and a spring.
- Besides, the structure constitutes a gas or air-filled chamber sealed by a diaphragm or piston.
- The diaphragm or piston moves up and down to absorb the shocks produced due to water’s momentum.
- The air and water are completely separate.
So, there is no need for maintenance to drain out water, as needed in the old models. A cylinder is present with the piston fitted inside; the piston moves due to the compression of air inside the cylinder due to the rise and fall in pressure.
As a consequence of this, kinetic energy release. It makes the pipes shake and rattle. For absorption of such shocks and to prevent deterioration of pipelines, water hammer arrestors are installed.
How Does Water Hammer Arrestor Work?
Now let’s get into “how a water hammer arrestor works.” Their work comprises the following steps.
- A water hammer arrestor diminishes the effects of water hammer in the plumbing system.
- After their installation, when the pressure increases, the pistons function by moving up and down.
- The pressure and counter pressure of air and water are responsible for this movement.
- In this manner, due to those contrary forces, the water hammer vanishes without causing any serious damage. The contrary forces act upon each other and neutralize the effect.
Water Hammer Arrestor Installation
You may wonder, how to install a water hammer arrestor and where should water hammer arrestors be installed? We will discuss the basic guides for the installation of a water hammer arrestor in brief.
For preventing clanking of pipes, water hammer arrestor installation is quite significant. Water hammer occurs when water suddenly stops or changes the direction of its flow, such as in washing machines or when the toilet stops filling. Water hammer arrestor installation comprises a few steps for successful insertion and functioning.
Moreover, while choosing a water hammer arrestor, certain factors must be considered:
- material,
- connection size,
- working pressure,
- durability,
- design,
- model, etc.
Items you’ll need
The materials you need for installation include:
- Pliers
- Water hammer arrestor
- Adjustable wrench
- Pipe wrench
- Towels or paper towels
Sometimes you may need:
- Expansion tools
- Soldering tools
- Tubing cutter
- T-fittings
Step 1: Check the water pressure
Check out the water pressure in the pipelines that are creating noises. If the pressure is above 75 psi, it means you need a water pressure regulator. If you already have a regulator installed, it means it is not working now. It needs to be fixed or replaced.
Step 2: Diagnosis of the problem
Diagnose the issue carefully. Check out the appliance or fixture which is causing the noise in your pipelines. The most common appliances contributing to such issues are washing machines, water dispensers, dishwashers, toilets, etc.
All of these appliances have solenoid valves. These valves are controlled electrically, unlike faucets, which reduce water flow when shut off completely.
Step 3: Action plan
After diagnosing the issue and locating the defective area, install water hammer arrestors in the pipes. For example, the installment of arrestors in washing machines occurs at both hot and cold-water supply lines.
There are simple screw-on devices that fit on faucet spigots where washing machine hoses are connected. Similarly, there are other devices available for different types of appliances and water supply lines.
Step 4: Turn the water off and disconnect the hoses
Shut off the valves tightly. They are present on the hoses of the appliance. Now, disconnect the hoses from valves.
Step 5: Insert water hammer arresters.
Thread water hammer arrestor on the valve of water supply. Tighten it with your hand. Now, use a tongue-and-groove plier. Be careful not to tighten it too much.
Step 6: Connect hoses.
Connect the hoses of the appliance to the water hammer arrestor. In the case of both hot and cold-water supplies, safety measures must be taken.
Connect the hot water hose to the hot water supply and the cold-water hose to the cold-water supply. Use a plier to tighten up the connections.
Step 7: Turn on the water.
Turn on the water. Check if there are any leaks. If you see any joints that are leaking, tighten them with pliers. The water hammer arrestors can work at any position, so install them the way you think they would work perfectly.
Types of Water Hammer Arrestors
Given below are Types of water hammer arrestors. There are two main types of arrestors; one fitted with pistons and another that lacks a piston. Those which consist of the piston are more effective.
There are different types based on the water hammer arrestor usage. Three commonly used types in residential water pipes include single-chambered, mini end stop style, and hose bib-style water hammer arrestors.
Piston-type water hammer arrestors and hydrotrols are commercially used and are also discussed below.
Single-chambered Water Hammer Arrestors
They are used commonly in ½ inch pipe systems, but they are also available for ¾ inch and 1-inch water pipes. Their installation is on any section of the water pipe at any angle.
- They consist of a sealed air chamber that absorbs energy from pressure fluctuation.
- They remain dry and moisture-free.
- They withstand water temperature up to 180 °F.
- If a threaded joint is not available, we can use a T-joint for its installation.
- They cost about $12-$15
Mini-end stops Water Hammer Arrestors
It comes with a threaded end. It fits only at a 90-degree angle. Their structure is such that it attaches directly to the hose of washing machines, dishwashers, etc. they require minimal space behind any interior wall.
- They are available for ½ inch, ¾ inch, 3/8-inch, 5/8 inch, and 1-inch diameter water pipes.
- The prices of these arrestors vary depending upon the diameter of the water pipes.
- They range between $30 and $40.
Hose-bib style Water Hammer Arrestors
They have a 6-inch wide PVC. As compared to the other two types, they can withstand greater pressure and high volumes of water.
- That is why they attach directly to the water intake area of washing machines etc., due to their larger diameter; they are not suitable to fit inside a wall.
- They are expensive.
- They can cost you up to $125, excluding installation fees.
All of the types mentioned above have unique features. They differ from each other in terms of requirement, replacement, durability, and maintenance.
Piston type Water Hammer Arrestors
They are available in a variety of series that are slightly different from each other.
They are compact. They allow installation in 2’’ into 4’’ wall space—they efficiently function whether inserted upright or horizontally at any angle.
- They operate at both domestic and commercial water systems.
- Copper is used in the casing.
- They withstand temperatures ranging between 33 °F and 250 °F.
- They have a sweat unit with an appropriate heat sink length.
- It avoids damage to the piston unit.
- They safeguard both the piping system and expensive equipment in line from adverse effects of hydrostatic shocks.
Hydrotrols/ Engineered water hammer arrestors
They are electrical, fast closing, pneumatic, spring-based devices. They provide a permanently sealed air or gas cushion and reduce pressure rise to a safe level in piping systems.
- They have a variety of models available.
- One of them is a HY-duty hydrotrol with a pressure gauge and valve charging vehicle.
- They are globally used on a commercial level.
Stainless steel bellows-type Water Hammer Arrestors
It is made of 304 stainless steel to prevent corrosion and result in a long life. All the joints are welded through the gas-tungsten arc welding technique.
- It results in burst pressure greater than 2000 psi.
- For durability and permanency, the welding of the fill point is closer to stainless steel.
- Like the older arresters, they don’t use mineral oil in their work.
- It vanishes all the possibilities of water contamination.
- It keeps the water systems potable.
Models of Water Hammer Arrestors
They are available in a variety of different models. Mentioned below are some of the best models.
- SharkBite 22632LF water hammer arrestor, Brass
They need T-fittings. Their installation doesn’t require glue or soldering. They constitute a durable brass construction.
- Sioux chief Mfg HD660-GTR1
It installs quickly and is best for dishwashers. They are best for residential spaces. They are cheaper.
- Supply Giant IBNQ0012 PEX Barb Hammer Arrestor
They sustain water temperature and pressure up to 250 degrees and 300 psi, respectively. They are both vertical and horizontally installed. They are flexible and quite effective.
Applications of Water Hammer Arrestors
Water hammer arrestor usage and applications are numerous.
- They are present in washing machines, dishwashers, refrigerator ice makers, and coffee machines.
- All quick closing valves have water hammer arrestors installed.
- Garden hoses and flush valves also have water hammer arrestors installed.
- A drinking fountain also requires an arrestor.
- The endpoints of piping systems have mostly water hammer arrestors installed.
- They are present in faucets and cisterns.
- Water hammer arrestors function successfully in both cold and hot outlets.
- Series-520-T and series 520-SC of Piston type water hammer arrestor is suitable for plumbing fixtures at offices, schools, public buildings, retails, hospitals, etc.
- 5060 HY-duty hydrotrol is the best choice for commercial laundry machines, bus washing stands, and larger capacity pumping systems.
- 5005-5050 stainless steel below units are compatible with most liquids conveyed in the piping distribution system.
- Bellows and piston-type water hammer resistors are very suitable for potable water systems.
Advantages of Water Hammer Arrestors
Water hammer arrestors have many advantages, and they are listed below:
- They are maintenance-free as compared to the older arrestors based on air chambers.
- There are seven different sizes based on the amount of shock they can control.
- They are a long-term and best solution for eradicating the problem of water hammers.
- They are installed between the water pipe and machine, hence reducing the pressure to safe levels.
- They absorb the shocks and minimize the slam sounds.
- It protects the appliances and water supply lines from damages.
- Piston-fitted water hammer arrestors function very effectively.
- They can eliminate piping vibration caused due to pressure surges.
- It prevents degeneration of plumbing. It also avoids the bursting of pipes or valves.
- Pipelines of electric water heater connections have water hammer arrestors installed.
- Those made of brass are versatile, durable, and used up to four times.
- They will last for a lifetime if installed properly.
- Arrestors used for washing machines have screw-on connections, making them simple to attach like a garden hose.
- They are good options for concealed locations.
- They fit inside the walls without using access panels, especially those with stainless steel. (Old models)
- Water hammer arrestor installation is easy in both new and old plumbing systems.
- It provides a secure and anchored structure of the pipe.
- Their chambers are well secured; therefore, they pretty much install at all angles, both vertically and horizontally.
Disadvantages of Water Hammer Arrestors
- The older models of water hammer arrestors need a lot of maintenance.
- Those not fitted with pistons are not very effective.
- Those models comprising air chambers need the water to be drained out of them since water is soluble in the air, so these chambers get flooded over time.
- The new models are maintenance-free, but some people report that it’s not the case. They also require a little bit of maintenance with time.
- The placement may vary from size to size. To install it correctly, we need to consult the instructions given by manufacturers.
- Hose-bib style water hammer arrestors are more costly than single-chambered and mini-end stop hammer arrestors.
- They are adjustable and easily installed, especially those with screw-on assembly.
- Hose-bib style has large diameters, so they are not suitable for installing inside a wall.
- They cannot solve all water hammer issues such as expansion and contraction issues and poor strapping issues.
- Piston arrestors do require access panels for installation.
- Some models require a water pressure reducer for effective functioning.
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Conclusion
Water hammer arrestors are shock-absorbing devices used in water supply lines. They effectively absorb the shocks produced due to surges in pressure. They are available in seven different sizes. They come in various models. For residential purposes, there are three main types of water hammer arrestors. Water hammers create loud noises, and they can damage the pipes and plumbing system. Water hammer arrestors are needed in such cases to avoid these plumbing issues.
Modern Water hammer arrestors’ construction prevents the combination of water and air. It helps in the proper functioning of the arrestors. Their installation significantly lessens the effects of water hammers. The old-fashioned pipe-capped air chambers are also in use. They have many limitations and are not very effective in controlling water hammers. Due to this reason, they are being replaced by piston-based arrestors. They are much more efficient than the old conventional arrestors.
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