The Air Tank Impact Wrench: Power And Precision

Air impact wrenches are a common tool in the automotive industry, used for tasks such as removing or fitting lug nuts on cars. They are also known as impact guns or rattle guns. While there are electric impact wrenches available, air impact wrenches are often preferred in workshops due to their lightweight and powerful nature. They are also safer than electric alternatives as they do not produce sparks and are not a shock hazard. The torque of an air impact wrench depends on the tool itself and the pressure of the air fed by the air compressor. When choosing an air tank for an impact wrench, it is important to consider the drive size of the wrench, the airflow of the compressor, and the size of the tank.

Air tank size and impact wrench use case

Air impact wrenches are a common tool in the automotive industry, used to fit or remove lug nuts on cars. They are available in four common drive sizes: 3/8", 1/2", 3/4" and 1". The size of the drive impacts the airflow requirements of the wrench, which is measured in CFM (cubic feet per minute).

The size of the air tank determines how long the impact wrench can be used continuously without switching on the motor. A larger tank will allow for longer continuous use. As a rule of thumb, the airflow from the air tank should be at least 3/2 times the minimum requirement of the impact wrench. For example, a 1/2" drive impact wrench with a requirement of 5 CFM airflow at 90 psi would need an air tank with an airflow rating of 7.5 CFM at 90 psi.

Air tanks can range in size from small (2 gallons) to medium (6-16 gallons) to large (30+ gallons). If you intend to use the impact wrench for a long duration, a larger tank is recommended. Additionally, if you plan to use multiple tools at the same time, a larger tank will be necessary to provide enough airflow.

It is also important to consider the physical size of the air tank in relation to the space available in your garage or workshop. Air compressors and air tools can be loud, so it is recommended to place the compressor away from the main work area to minimise noise.

A 10-lb Power Tank can be a good option for a portable, powerful air system. It can easily be unmounted and carried, and provides enough pressure and flow rate to power most tools.

Airflow from the air compressor

The airflow from the air compressor is an important consideration when choosing a suitable air compressor for an impact wrench. The airflow is measured in CFM (cubic feet per minute) and it is important to check the minimum CFM ratings recommended by the impact wrench manufacturer.

The airflow from the air compressor should be at least 3/2 times the minimum requirement of the impact wrench. For example, a 1/2" impact wrench typically requires around 4-5 CFM of airflow at 90 psi. Therefore, the airflow rating of the air compressor should be 3/2 x 5 = 7.5 CFM.

A larger air compressor with a higher airflow rating will allow for a longer continuous use of the impact wrench without needing to switch on the motor. As a rule of thumb, the air compressor tank size should be at least 5 to 6 times the airflow requirement of the tool. For instance, if the impact wrench requires 5 CFM, then the compressor tank size should be at least 25 to 30 litres (6-8 gallons).

It is worth noting that these are just recommendations. If you plan to use multiple tools or have a large garage or workshop, investing in a larger air compressor with a higher airflow capacity and a bigger tank size may be more beneficial.

Additionally, the drive size of the impact wrench also plays a role in determining the required airflow. Impact wrenches with smaller drive sizes, such as 3/8" or 1/2", require less airflow compared to those with larger drive sizes, such as 3/4" or 1".

When choosing an air compressor, it is important to consider the size of the air tool, how long you intend to use it continuously, the number of tools used simultaneously, and the size of your garage or workshop area.

Impact wrench drive size

The size of an impact wrench is the distance between the flat edges of the driving anvil, and this dimension will determine what jobs the wrench is able to tackle. The most common sizes are 1/4-inch, 3/8-inch, 1/2-inch, 3/4-inch, and 1-inch.

The smallest impact wrenches, 1/4-inch and 3/8-inch, are generally compact and easy to use in tight spaces. They are perfect for bolts that are 10mm in diameter or below, and for situations where accuracy and precision are more important than power.

The most common size is the 1/2-inch impact wrench, as it offers the best balance between precision and power. This size has enough power to do a wide variety of jobs while remaining safe for smaller tasks.

The two largest sizes, 3/4-inch and 1-inch, are less common as they are often too powerful for home projects. However, they are frequently used in professional settings, such as construction sites, where their power is more useful.

When choosing an impact wrench size, consider the type of job you will be doing. For example, 1/2-inch is the best size for changing car tires, while 1/4-inch or 3/8-inch is recommended for changing lawn mower blades, as precision is more important than power for this task.

Air compressor placement in a garage or workshop

When setting up an air compressor in a garage or workshop, there are several factors to consider for optimal placement. Firstly, it is important to choose a suitable location for the air compressor itself, ensuring proximity to a power supply and easy access for your projects. If you have limited space, consider a portable air compressor that can be disconnected and moved when needed.

For the compressor setup, you can choose between a linear system, with pipes running from the compressor to one or two walls, or a closed-loop system, which is ideal if you plan to use multiple applications simultaneously. When running air compressor lines, it is recommended to use materials such as copper, aluminum, or stainless steel to minimize pressure loss.

Additionally, you should aim to reduce the number of elbows, tees, and connections, as well as slope the horizontal piping slightly downwards to prevent water collection. Include ball valves or shut-off valves at the compressor outlet and each drop to control the airflow and facilitate maintenance.

To optimize your setup, consider soundproofing the compressor by placing it in a well-ventilated wooden box or cupboard to reduce noise. You can also make the compressor more portable by adding wheels or using a hose reel for easier maneuverability.

When it comes to pipe material, smoothbore piping made from copper, aluminum, or stainless steel is recommended to minimize pressure loss over each unit of length. Semi-flexible rubber tubing approved for high-pressure applications is another suitable option.

Remember to plan your layout carefully, considering the number of workstations, plumbing routes, noise levels, drain positions, and future expansion possibilities. By following these guidelines, you can achieve an efficient and effective air compressor setup in your garage or workshop.

Air tank pressure and impact on power

The pressure in a pressure tank does depend on the amount of air. The air in a pressure tank cushions the pressure and ensures smooth operation. However, too much air can cause issues, from inconsistent water pressure to unusual noises and vibrations, and even potential damage to the tank's integrity.

The correct air pressure for a pressure tank, measured with the pump off and the water pressure relieved, is 5% less than the cut-in pressure setting of the pump. This is important because it allows the pressure tank to buffer the pressure and flow of the system when the amount of water being discharged is less than the amount being pumped.

For example, if a pump delivers 50 litres per minute (lpm), but a shower only uses 20lpm, the pump needs to run for only two-fifths of the time. Without a pressure tank, the pump would need to start and stop rapidly to regulate itself to 20lpm. A pressure tank, however, contains air, which is compressible. So, the pressure tank can accept the extra 30lpm, compressing the air until the pressure builds up and the pump switches off. This allows the pump to achieve the required run time without causing rapid pressure fluctuations.

In terms of raw power, a 10-lb Power Tank with a quality impact will outperform any cordless impact wrench. For particularly tough jobs, you can increase the pressure to outperform even large shop compressors.

Therefore, when it comes to air tank pressure and its impact on power, it is clear that maintaining the correct air pressure is crucial for the optimal performance of an impact wrench. Too little or too much air pressure will result in decreased power and efficiency, as well as potential damage to the pump and pressure tank.

Frequently asked questions