Fan Buyer's Guide
Fans spin and cool... simple, right? Actually, electronic components are never that simple. When it comes to purchasing the correct fan, you have to look at all the specifications such as size, speed and control in order to make the right choice for your application.
You should first know the required input type. The most common voltage inputs are 5VDC, 12VDC, 24VDC, 48VDC, and 115-220VAC powered. Be sure your system can provide the required amount of current for the fan to operate to expectations.
The size of the fan is determined by how much space is available. Larger fans do not always provide higher speeds or better cooling, but rather that a larger area will receive cooling. Conventional standards list the sizes in millimeters and the most common are:
• 40 x 40 x 10
• 80 x 80 x 25
• 120 x 120 x 25
Speed and Airflow
The rotational speed of a fan is usually given in revolutions per minute (RPM). Combine the RPM speed with the static pressure of the given environment and you get the airflow of the fan. This is usually given in cubic feet per minute (CFM). This specification will tell you which fans push the most air and provide the best cooling. You will typically see specifications for nominal speed and operating voltage range of the fan. A fan's speed and airflow correspond to the rated voltage. Keep in mind that if the voltage to the fan is decreased from this value, the speed and airflow will also decrease.
Most fans have a 2-lead positive/negative connection, but some may include extra leads for various purposes. A third lead can be used for locked rotor protection (in case something gets caught in the propellers). Some fans also have an energy saving feature that uses a temperature sensor to only allow the fan to start once the device reaches a specific temperature. A tachometer lead may also be available for users that want to know exactly how many RPMs are being provided.
The bearing on a fan tells you how the fan is built and also provide you with an idea of how long it may last. Ball bearing fans are the most common as they are simple and effective. They are more durable at higher temperatures and fairly quiet at high speeds. They have a long lifespan, generally lasting over 60,000 hours.
Sleeve bearing fans are also very common. They use lubricated sleeve surfaces which can be self-lubricating and require little maintenance. Although they are typically less expensive, they are also known to be less reliable long-term and do not perform as well as ball bearing fans in higher temperatures.
Hypro bearings are exclusively from Adda Fans. They are recommended for fans with a minimum thickness of 10mm and for applications under 70°C. Hypro bearings are made of copper ferroalloy which have an above average lifespan and are water-resistant and good for low-noise applications. They also use lubricating oil within the system, which reduces friction but has the potential to cause additional wear once it dried.
Vapo bearings are used exclusively from Sunon Fans. They are designed to eliminate wobbling, so they stay incredibly stable in all applications. They’re also dust-proof which will lead to a longer life expectancy.
AC Tube Axial Fans
AC tube axial fans improved air-flow and lower power consumption over conventional axial AC fans. These fans are highly efficient and are great for moving air containing noxious fumes.
Blower fans provide low noise and high volume for cooling and free ball bearings reduce rotational friction. They have three main components: the fan blades which moves air, a motor with moving parts to spin fan blades and a power supply to provide electrical power. Air is typically blown out of a smaller port than the intake. Airflow is also perpendicular to the intake, possibly even the same direction as the rotation.
Brushless DC Fans
Brushless DC fans do not draw constant currents. They are relatively quiet but depending on the speed and level of balance, there may be some vibration generated. Keep in mind that the label on a brushless DC fan will be given as an average current. The speed and airflow of most DC fans are proportional to the voltage supplied. Brushless DC fans are usually available at three voltages: 5V, 12V, 24V and 48V.
Thermoelectric coolers, also known as TEC or Peltier, create a temperature differential on each side. One side is cool and the other is hot. They lower the temperature of an object below ambient and also stabilize the temperature of objects in varying ambient conditions. This phenomenon can be useful when it is necessary to transfer heat from one medium to another. This effect can also be used to generate electricity. The direction of cooling and heating is determined by the polarity of the applied voltage.
There are more considerations to take note of such as agency approvals and noise levels, but those are fairly straightforward. If your purposes require certain approvals, please make sure they are marked so.
Click here for explanations on Certifications and Approvals.
Fan Guards and other Accessories
DC Brushless Fan
Heatsinks are large, passive components made up of stacks of aluminum fins that allow heat to dissipate efficiently. Fans are attached to each side of the heat sink. They improve the unit’s ventilation, circulating the cool air inside more evenly and expelling heat outside more effectively, or vice versa. In thermoelectric coolers, they can be combined with a heat pump on the cold side to keep the interior cold and on the hot side for the exterior, depending on the application.
Fan Power Cords
Jameco has a selection of fan power cords. They serve as great replacement cords if your existing power cord has been damaged.
Fan Grab Bags
Jameco fan grab bags provide an assortment of AC and DC fans great for many applications.