What is the first fan law?

Author: Prof. Angel Kshlerin  |  Last update: Wednesday, August 13, 2025

These three Fan Laws demonstrate how changes in speed will impact airflow (Fan Law #1), static pressure (Fan Law #2), and power requirements (Fan Law #3). This is the most straightforward of the Fan Laws. It states that the volume of air moved by a fan is directly proportional to the speed of a fan.

What are the three fan laws?

To summarize these 3 fan laws, flow changes proportionately to speed. Static pressure changes as a function of the change in speed squared. And brake horsepower changes as a function of the change in speed cubed.

What is the first affinity law?

First Affinity Law: speed and flow rate

The first law states that if you alter the speed of a fan or pump, the flow rate of air or water changes proportionally. Simply put, double the speed, and you double the flow.

What is the power law of a fan?

The third fan law relates the total or static air power (and the impeller power), to the fan rotational speed: Power, is proportional to the cube of the fan rotational speed. -Since velocity in a duct is seldom uniform across any section, a traverse is usually made to determine average velocity.

What is the cube law of a fan?

Cube Law Explained

The relationship between the speed and power of a fan or a pump is called the Cube Law and can be built up step by step. The flow is proportional to the speed: 10% slower = 90% flow. The power is proportional to the speed cubed.

Three Key Fan Laws Explained: Airflow vs. Static Pressure vs. Horsepower

What is the fan law for horsepower?

Fan law # 3 tells us that horsepower will increase by the CUBE of the cfm ratio. So you would need to change from a 20 HP motor to a 50 HP motor! What would the static of the system be now? Fan law #2 tells us that the static pressure will increase by the SQUARE ratio of the cfm.

Is The Square Cube Law Real?

The square–cube law was first mentioned in Two New Sciences (1638). This principle states that, as a shape grows in size, its volume grows faster than its surface area. When applied to the real world, this principle has many implications which are important in fields ranging from mechanical engineering to biomechanics.

What is the fans first law?

In late 2023, Senator John Cornyn introduced the Fans First Act (the “Act') which aims to increase ticket sale transparency, protect American consumers, and stop bad actors. [1] The reaction to the bill, which has been referred to the committee on Commerce, Science, and Transportation, has been mixed.

What is the affinity law?

The affinity laws express the mathematical relationships between the several variables involved in pump performance. They are used to predict what effect speed or impeller diameter changes have on centrifugal pump performance. One can trim an existing impeller and the affinity laws will apply to the new conditions.

How to convert RPM to CFM?

If we want to calculate the CFM (Cubic Feet per Minute) for a 4 cycle motor we can multiply the cubic inch displacement of the engine by the maximum rpm (Revolutions Per Minute) and divide the result by 3456. Then we multiply the results by the volumetric efficiency of the motor.

What is the first ever law?

The Code of Ur-Nammu is the oldest known surviving law code. It is from Mesopotamia and is written on tablets, in the Sumerian language c. 2100–2050 BCE. It contains strong statements of royal power like "I eliminated enmity, violence, and cries for justice."

What are the affinity laws for fans?

The affinity laws (also known as the "Fan Laws" or "Pump Laws") for pumps/fans are used in hydraulics, hydronics and/or HVAC to express the relationship between variables involved in pump or fan performance (such as head, volumetric flow rate, shaft speed) and power. They apply to pumps, fans, and hydraulic turbines.

What is the rule of first law?

Newton's first law: An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force. Note the repeated use of the verb remains.

What is fan rule?

In summary, fan laws are essentially about impellers and what happens to their characteristics when they undergo changes in rotational speed, air density, or are scaled in size. They also help with the understanding of ventilation systems and the relationship between volume air flow rate and system total pressure.

What is the difference between RPM and CFM?

Fans cool by moving air, which is measured in Cubic Feet per Minute (CFM). The is the only metric of its effectiveness. RPM is how fast the fan spins to make those CFMs. Lower RPM usually means quieter, but blade design and the enclosure have more to do with it.

What are the laws of 3?

The Law of Three is a law of creation. Creation of the human life. The law states that for anything to be created or an event to materialize three forces must be present. An active force (father), a passive force (son), and then a neutral force (holy-spirit).

What is the Catholic canon law of affinity?

In Catholic canon law, affinity is an impediment to marriage of a couple due to the relationship which either party has as a result of a kinship relationship created by another marriage or as a result of extramarital intercourse. The relationships that give rise to the impediment have varied over time.

What is the pump act?

​The PUMP for Nursing Mothers Act (“PUMP Act”) is a new law that makes several important changes to the Break Time for Nursing Mothers law, which has required since 2010 that employers nationwide provide reasonable break time and a private, non-bathroom space for lactating employees to pump milk during the workday.

What is the Charles law state?

Charles's law, a statement that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature, if the pressure remains constant.

What is the legal age for OnlyFans?

Because OnlyFans is only for people over the age of 18, there are no parental controls. OnlyFans is not responsible for reporting content that violates their terms of service; instead it falls to individual users. You can either restrict or block an account.

What is the first fan act?

The Fans First Act aims to address flaws in the current live event ticketing system by increasing transparency in ticket sales, protecting consumers from fake or dramatically overpriced tickets, and holding those who engage in illegal ticket sale practices accountable.

What is the 11th law?

Eleventh Amendment Suits Against States

The Judicial power of the United States shall not be construed to extend to any suit in law or equity, commenced or prosecuted against one of the United States by Citizens of another State, or by Citizens or Subjects of any Foreign State.

What is Power of 4 called?

Fourth powers are also formed by multiplying a number by its cube. Furthermore, they are squares of squares. Some people refer to n4 as n tesseracted, hypercubed, zenzizenzic, biquadrate or supercubed instead of “to the power of 4”.

What is the universe square law?

The inverse-square law states that the intensity (I) of a quantity, such as light, is inversely proportional to the square of the distance (d) from its source. Mathematically, it can be expressed as: I ∝ 1/d^2.

Do dinosaurs violate the square-cube law?

Many dinosaurs weighed a lot less than you would expect, given their size. Tldr: Square-cube law would only be violated by scaling-up an existing animal, not by an animal gradually evolving large-size adaptations.

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