CV1800 with Australian Spec 4HP Motor - 15 or 16" impeller?

D

DomAUS

New member
Hello,

I am about to order a Clearvue CV1800. I am in Australia and the units here (both CV1800 and CVMax) are spec'd with 4 hp motors. The CV1800 is standard with a 15" impeller and the CVMax with a 16". Both units are supplied with a VFD to convert to 60Hz 3 phase supply to the motor.

I will be running 6" ducting throughout and will be venting outside. I estimate my static pressure will be about 10-12" at the farthest point and a minimum of about 8".

I was going to order my CV1800 with the 16" impeller based on positive reports from the US claiming increased CFM. I also figured that if the CVMax was supplied with the 16" impeller and 4hp motor and given it's larger ducting and therefore higher CFM, the motor should not be overloaded on 6" ducting (and therefore lower CFM) with the CV1800.

Should I stick with the 15" impeller? I'm worried about overloading the 4 hp motor if I draw enough CFM to make the 16" impeller effective. Is the 15" impeller actually going to perform better on my setup given the 4hp motor limit (vs the US 5 hp motor).

It's hard to figure out without a fan-power curve.

Any help would be appreciated. I'm about to put in an order. 15" or 16" ???

Cheers,
Dom
 
Dom,
My sense is that this needs to be answered by Clearvue. My CV1800 runs about 3.5 HP maximum with the 15" impeller and if I use the fan laws that say power increases as the cube of fan diameter I come up with about 4.25 HP. That is, 3.5 times (16/15)^3. One thing you can check is to see if the inverter frequency is variable. You may be able to slow the fan slightly to keep the power where it should be.
bababrown
 
Thanks mate. If you are correct, then at that condition (any idea what SP / CFM that power is at?) I would only need to reduce the frequency to 59 Hz to bring the power to 4HP or 58 Hz to reduce power to about 3.75HP. I'm fairly sure the VFD allows me to change the frequency.

I'm leaning towards the 16" but am worried that depending on the Fan Curve I may actually get higher CFM at 4HP using the 15" fan, particularly if my static pressure is on the lower side (I will be venting outside).
 
Perhaps the best solution is to purchase a 4kw (5.33hp) motor available with the same flange mount dimensions? Then I have no chance of motor overload and provided I don't draw more than about 20 amps from my 240v circuit that will be fine as well. Is this the best solution?
 
DomAUS,

I cannot answer your questions, but I can point you to Clearvue Fans curves. A member “wavery” posted it as a .pdf attachment to a reply in a thread that discusses the availability of fan curves. There is also some discussion from 2013 about motor and impeller sizes, though I am not sure how much help it will be.

I recommend contacting Clearvue. On the main web page is a contact link where you can send an email, thereby avoiding international calling charges.

The Fan Curve thread is at:

Clear Vue Cyclone Forums > Clearvue Cyclones > Product Questions -->Thread = “CV1800 fan curve”

http://www.clearvuecyclones.com/Bullentin/showthread.php?t=1481&highlight=curve
 
Thanks jsbrow,

I've seen those curves but what I need is the fan performance curves that show hp against cfm for a given static pressure so I can determine if there is any chance of overloading a 4hp motor at my range of static pressures and using a 16" fan or if I would get better performance due to operating at a sweeter point in the curve using a 15" impeller.

Thanks for the advise re contacting clearvue. I'll give that a shot. At this stage I'm leaning towards getting a 4kw motor (nearly the same price and should bolt straight on) to avoid any possible issues. Unless someone has better advice.
 
DomAUS,

While I am not sure this provides the information you need, this link includes a “Blower Fan Table”. The web page purports to show data along the lines you seek.

During my cursory look at the web page, I did not see from where these data came nor did I see where Bill Pentz discusses his methodology. The “Blower Fan Table” is entitled “Hobbyist Fan Table for Shop with Ducting, Cyclone, and Cartridge Filters” and is found about 2/3rds the way down the page at

http://billpentz.com/woodworking/cyclone/dc_basics.cfm#blower_fan_table


The “Blower Fan Table” shows CFM & BHP for various Duct Size, Static Pressure, Impeller Size, and Required Motor HP. I do not know what “BHP” is and I assume “BC Wheel” means impeller size.

By the way, CV sold me the CV-1800 with a 16” impeller and a 6” cyclone inlet and a 5hp (3.7KW) motor (if I did the power conversion correctly). I have not had it nearly long enough to know whether the motor is correctly sized, but that is their U.S. package.
 
Thanks again. I know that clearvue offer the 16" impeller on the cv1800 in the US and this is why I started considering this "upgrade" . But our motor is 3kw not 3.75kw so I'm not sure if our motor will handle the airflow volume possible with the larger impeller (assuming pressure loss is low) without burning out the motor.

The table Bill Pentz provides in your link is based on data from Cincinnati fans (bc is backwards curved and is the type of impeller used in most extractors). Their fans are 15.5 and 16.5" and also have taller blades and a higher blade count I believe so I'm not sure if Bill adjusted the hp numbers to reflect the smaller impellers in the clearvue.

I think that given we offer the cvmax system with a 3kw motor in australia and given that this system will flow more air the cv1800 couldn't be overloading the motor if the cvmax doesn't. However in order to be safe not sorry I'm leaning towards getting a 4kw motor with my system as I don't see a downside to this.
 
Ok. I found a downside to the 4kw motor. It is only available standard in 415v 3ph and the VFD supplied with the clearvue in australia will only work with 240v 3ph motors. The 4kw can be rewired to delta 240v configuration but that would make the motor nearly 3 times more expensive so not worth it for a "just in case ".
 
Ordered the Cv1800 with 16" impeller and 3kw motor today. Will update how it goes once I've received it and have it up and running. The 3kw motor is rated for 5.75Amps per phase so given it's 86 % efficiency that's still about 3500w or 4.75hp. Should be fine
 
Just to update. I installed the cv1800 with 16" impeller. Without inlet ducting connected yet the VFD only reads about 10.5amps at 240v so it's not going to tax the 3kw motor at all.
 
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