Start Searching the Answers
The Internet has many places to ask questions about anything imaginable and find past answers on almost everything.
A A A is the cross sectional area of a section of the pipe, and v is the speed of the fluid in that section. So, we get a new formula for the volume flow rate Q = A v Q=Av Q=AvQ, equals, A, v that is often more useful than the original definition of volume flow rate because the area A is easy to determine.
Q=Vt Q = V t , where V is the volume and t is the elapsed time. The SI unit for flow rate is m3/s, but a number of other units for Q are in common use. For example, the heart of a resting adult pumps blood at a rate of 5.00 liters per minute (L/min).
The flow rate of a fluid is the volume of fluid which passes through a surface in a given unit of time. It is usually represented by the symbol Q.
By multiplying air velocity by the cross section area of a duct, you can determine the air volume flowing past a point in the duct per unit of time. Volume flow is usually measured in Cubic Feet per Minute (CFM). Concept of Air Velocity can be used in air conditioning, heating and ventilating work.
CFM = (fpm * area), where fpm is the feet per minute. To find the cubic feet per minute, substitute the FPM value with the area after the area is squared.
To calculate the drops per minute, the drop factor is needed. The formula for calculating the IV flow rate (drip rate) is total volume (in mL) divided by time (in min), multiplied by the drop factor (in gtts/mL), which equals the IV flow rate in gtts/min.
The rule of thumb is that you need at least 1 CFM per square foot of room area. To determine the square footage of your bathroom, multiply the length times the width.
Step 1: Calculate Bathroom Size: 20′ x 10′ Bathroom = 200 square feet. Result: You will need a 150 CFM fan for this bathroom.
“The conditioned air quantity for air conditioning should be about 400 CFM per ton of cooling capacity.” The difference is the amount of heat which the air has either added to or removed from the space. By careful measurement it has been found that it takes 0.24 Btu to raise one pound of air one degree Fahrenheit.
400 to 600 CFM = 6” to 8” duct. 700 to 900 CFM = 7” to 10” duct. 900 to 1200 CFM = 8” to 12” duct. 1200 and higher CFM = 10” and up duct.
1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on.
One cfm is needed per square foot (1 cfm/sq ft) of floor area. This is the average air quantity required for a room or an entire building. This number is based upon an averaged heat load calculation for comfort cooling.
Flex duct moves less air than hard pipe, if you look at 7″ hard pipe on the duct Calculator you will see that at 900 FPM and . 05 static you will see it moving around 125 to 130 CFM.
Reviewing the chart, a 4” pipe will convey 395 CFM at 4500 FPM.
Equivalent diameter for rectangular and circular ducts – air flows between 100 – 50000 cfm
|Air flow – q – (Cubic Feet per Minute, cfm) (m3/s)||Rectangular Duct Sizes (inches) (mm) x (mm)|
|800 (0.36)||8 x 15 10 x 12|
|1000 (0.45)||10 x 14 12 x 12|
|1300 (0.59)||12 x 14|
|1400 (0.63)||12 x 15|
To calculate CFM, you need to know the size of your heating or cooling unit in tons. Multiply this number by 400, which is the average output of an HVAC unit. Then divide by the total square footage of your home. This will give you the multiplier for all your rooms’ CFM.
350 to 400 CFM per ton of cooling is required for proper air conditioning system operation. For example, if you are checking a 3 ton system, the airflow required is between 1050 and 1200 CFM.
They found most small shop stationary tools need about 1000 cubic feet per minute (CFM) of airflow to have good fine dust collection and only need about 350 CFM for good “chip collection”.
Brushless motors also generate more performance in terms of cfm and suction pressure. Shop Vac points out that its 2½-hp., two-stage vacuum operating with a conventional motor can generate 90 inches of suction and 100 cfm. This compares with 125 inches of suction and 110 cfm for its 2½-hp.
around 125 CFM
To calculate loading, take the dust being sent into the collector (lb/hr) and multiply it by 7000 grains/lb. You then calculate the total system air volume per hour. Finally, divide the grains per hour by the total airflow in an hour to get grains/cu ft.
Designed to handle high-volume dust loads, a dust collector system consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system. It is distinguished from air purifiers, which use disposable filters to remove dust.
For a rectangle, multiply the length by width, then multiply that number by 28 to find the flow of CFM at 4,000 feet per minute (fpm) airflow. Find the largest CFM number out of all your tools, and that’s what you’ll go on for the required rating for your dust collector.