how to determine pulley size for electric motor fan flow rate calculation

Fan & motor CALCULATIONS, Pulley size, RPM, air flow cfm hvac rtu

           Hi,friends today we are discuss about how to determine pulley size for electric motor fan flow rate calculation. so ,please read full article for more knowledge.

     

        During this Article we're performing some fan calculations and we're see the way to calculate the fan pulley diameter, the motor pulley diameter, the fan revolutions per minute, the motor revolutions per minute and also what the adjusted air flow would be ,if we were to vary these.

             Now, with the fan, if it's already installed, then you'll should get a sheet , which tells you this is often just the planning data. So everything you would like to understand about the fan. we will look today the way to calculate these and fill the blanks in and if you are a designing the ventilation , then we're check out the calculations for a way to truly calculate and enter these values.

             Now, we're be employing a few technical terms today's like fan, motor,pulleys, RPM, etc. so just to bring it up to hurry thereupon Exhaust the fan. we have got the motor, Then we have got the fan. Now these two which are connecting. we have got the belt pulley . So this is often the pulley wheel And another pulley wheel. So one is that the fan pulley wheel and another is that the motor pulley wheel. When the motor spins,obviously that's transfer that rotation over through the belt and into the pulley of the fan. which can rotate that and as that fan begins to spin.

           

pulley rpm formula

       That is what provides and pushes the air off into the building. therefore the rate that the motor spins is understood because the RPM, the revolutions per minute And also the speed that pulley spins is understood because the RPM,revolutions per minute. So we'll have a glance at what size they have to be and the way fast they have to spin so as to realize the proper flow , if you were to vary them, what the air flow change would be the adjusted value .

           Therefore the first one we're getting to calculating the fan pulley diameter. we've the metric and imperial calculations on here And we have got a formula over here . I find it just makes it tons easier to follow the numbers but the formula we'd like for this , 

           The fan pulley diameter is adequate to the motor pulley diameter multiplied by the division of the motor RPM divided by the fan RPM and that we got some data within the calculations . So we will get these figures from the manufacturer if you haven't already purchased the equipment then you'll look it up online and you'll see what the RPM is be for these fans and motors.

         
pulley size vs rpm calculator

         For the fan, that's be the RPM you would like to supply x amount of ventilation or air flow and therefore the motive the RPM that it's rotate at. So for the primary one, we have got a 95 mm diameter pulley on the motor pulley diameter. So, there's 95 mm across or 3.74 inches and that we know that the motor is rotating at 2861 RPM. Same for the Imperial then the fan so as to realize the air flow that we'd like , it's gonna be rotating at 3020 RPM. Same for the imperial.

          So if we do the division first then you will see , we get but one where it's 0.94735% and it is a percent because ,we're doing a division of an equivalent units, so, it becomes a ratio so it is a percent. Then we have got 95 mm multiplied by that percent equals 90 mm or 3.54 inches ,so the fan pulley diameter, that must be having a diameter of 90 mm so as to realize a design that we'd like . 

          Now differently to calculate this, if we were to possess slowed the motor down. We've changed the flow that we'd like servicing the ground . half the ground is cleared out and that we make some energy savings or change the planning data, then we will use this formula here. 

      

cfm calculation formula

         Therefore the new fan pulley diameter is adequate to the old fan pulley diameter, multiplied by the old air flow , divided by the new air flow . So for this though, just put during a 10% reduction from the first from the planning data. And if we punch those numbers in, then we will use that for the imperial side also . Doing the division,obviously cancels that out and makes that that a percentage for a ratio. So it's 1.11%. Multiply that by the first fan pulley diameter which lets us know that the new diameter must be 100 mm or 3.93 inches.

       Therefore the next thing we will calculate is that the motor pulley diameter. Now there might be various reasons why this has changed. there is a new motor being replaced, a replacement fan has are available so you would like to understand what diameter that pulley must be to realize that correct air flow . 

fan flow rate calculation

         For that we'll use this formula here. therefore the motor pulley diameter is adequate to the fan pulley diameter, multiplied by the fan revolutions per minute, divided by the motor revolutions per minute. Again, you'll get this information from the manufacturer or from the designer, if it's already installed. So if we just drop the numbers in. So on the fan, we've a 90 mm diameter pulley or 3.54 inches and we'll do the division between the 2 RPM's, canceling out the RPM's 

 leaving us with 1.056%. Multiply that by the fan pulley diameter which gives us what the motor pulley diameter must be which is 95 mm or 3.74 inches. 

         Differently to try to to this, if we all know there has been a change within the flow and that we got to know what the change in diameter for the pulley are going to be on the motor, then we will use this formula here, which is that the new pulley diameter is adequate to the old motor pulley diameter, multiplied by the new air flow divided by the old air flow . 

        Now we all know what the old air flow is and therefore the diameter of the pulley. this could be the new air flow and you'll calculate otherwise you can take it from the new manufacturer , But if we drop these numbers in then obviously these will wipe out on each side . in order that will give us a percent again and that we can see that the first pulley diameter multiplied by that percent is equal now to 85 mm or 3.73 inches. that is the new motor pulley diameter. 

       So then we will check out what the fan RPM must be so as to realize our criterion . for that we'll use this formula here which is that the fan RPM is adequate to the motor RPM, multiplied and that we already know these figures. We should've calculated them or taken them from the manufacturer of any new equipment or from the planning data. So if we drop the numbers in, then obviously we'll get right down to a ratio again if we do a division of the pulley diameters then we will multiply these together which will bring us to 3020 RPM on both metric and imperial because is that the "> it is the same units there which is the speed that the fan needs rotate at to realize the planning in flow .

       Now we will also calculate the motor RPM and that we do this using that formula here. therefore the motor revolutions per minute, equals the fan pulley diameter multiplied by the fan revolutions per minute, divided by motor pulley diameter. so, we will drop those numbers there in and this may then begin at 2861 RPM on each side , Imperial and metric.

      Again you'll just calculate these or look them up from the manufacturers. Now if you've got made any changes to the fans and therefore the motors, then we would like to understand what the adjusted air flow are going to be and can it satisfy the planning criteria or are we making the reduction so as to scale back the air flow to form some energy savings? And if that is the case then we will use this formula here therefore the new air flow is adequate to the old air flow multiplied by the division of the fan RPM. The new divided by the fan RPM of the old.

       So we will then stick these figures here in. So we all know what the old flow was and what they adjusted RPM goes to be and therefore the original RPM's so we'll stick these beat , this may bring us down .so obviously another ratio and that we can multiply that out and that'll bring us to 1.638 meter's cubed per second. There should be a cube Or 3470 cubic feet per minute.

       Okay that's it for this text . many thanks considerably . I hope you've enjoyed and it's helped you. If you've got any questions, please leave them within the comments section below. do not forget to love , subscribe and share and also check on our website https://automationwale.blogspot.com once more , many thanks considerably friends.