Radbox (slow but sure)

jlrii · 01-02-2005, 12:04 PM

Finally got my blower for a new radbox (was backordered for 2-3 months) It will be mounted centrally in the case drawing from the top with the rads on either side, with acoustic baffles between the blower and rads to reduce noise.

The case is a Chenbro 4u deep Rackmount, still deciding on the pump(s), I have a few in hand. The box is meant to serve 3 or 4 computers so I am need to go heavy on the rads. Most likely 2 120.3s. I am looking for suggestions on them. Air resistance is not much of an issue as the blower should be easily push over 11 M³/ min at a reduced speed through a single thermochill type core, more through 2 of them. I have about 21 x 6.5" (53 x 16.5cm) clear space on either side of the case. So mostly looking for the most fin area and thickness "should" not be an issue. It would be nice if manufactures provided info on fin spacing and actual depth....googled for a while found nothing...

Also wondering about the jet size on G4's I want to include an inline filter and I need to specify the screen size but would rather not drain my existing rig to measure them.

Thanks for any advice,
JR

bigben2k · 01-02-2005, 01:24 PM

That's a big one (8 1/4"?!?). How much did it run you?

jlrii · 01-02-2005, 02:24 PM

From all that I've read using a large blower at reduced speed is the way to go for reduced noise. From BillA's review it looks like moving 4.3 lpm of air across a single 120.3 produces about 62.3 pa, so two of them should be about half that or about 31 pa. At that pressure it should be able to move just about 480 cfm CFM, way more than needed. So I hope to run @ 42% speed and get 200 cfm out of it as CFM1/CFM2 = RPM1/RPM2. (tho it will be fun to crank it up and watch the papers fly). It cost 63.58USD From here. I havn't run it yet to see how loud it is, the box will include a 115v speed control to tone it down. I am hoping with its sheer size I can run it pretty slow and hopefully quietly for everyday use. It has a PSC motor so it should not heat up to badly or stall at lower speeds.

jlrii · 01-02-2005, 03:05 PM

I havnt done the math yet to see how loud it may be...I will have to physically measure rpm to do that as it is not shown on the fan....may be 2550 rpm it saya 2550min-1 ???? EBM's german site seems to list fan speeds like that from what I can tell.

3. Acoustic Noise
Cooling electronic systems by air is a common practice throughout the industry. In cases where the system is cooled by forced convection, a blower or a fan is used as the air mover. The size of the air mover is a function of the cooling requirements for the system and the individual components. Associated with the air movers is the acoustic noise that is generated as the result of the air moving within the system. If we look at the sound power level (Lw) for a blower, we can see the role air velocity plays in the noise generated by a blower, (reference 3)

Lw=logh(G / D3N)+2logP+logG+12 (8)

Likewise, LW for the small axial-flow fans is given by the following equation:

Lw=3.71logVt+0.96logG-10.8 (9)

where,

G = the volumetric flowrate
N = the impeller speed in rpm
D = the impeller diameter
P = static pressure drop
Vt = the tip speed of the impeller

MaxxxRacer · 01-02-2005, 05:00 PM

now that my friends is a fan....

wonder what the nosie levels on that sucker are..

Kobuchi · 01-03-2005, 12:17 AM

That, is not a blower.

Nice and compact. Wow it looks cool. And low noise without any housing.

jlrii · 01-03-2005, 05:21 AM

Well yeah, actually a motorized impeller. Not exactly quiet at full speed....500CFM=70dba. hopefully a lot quieter than that when slowed down 200CFM=?DBA.

Ls7corvete · 01-03-2005, 10:06 AM

Join the club my friend. These motorized impellors are the way to go. I get such a nice range on mine, silent to insanly powerful and loud. Mine is small enough to go in the case though

I bet more people will be trying this soon.

01-02-2005, 12:04 PM	#1
jlrii Cooling Savant Join Date: Feb 2004 Location: Massachusetts, USA Posts: 158	Radbox (slow but sure) Finally got my blower for a new radbox (was backordered for 2-3 months) It will be mounted centrally in the case drawing from the top with the rads on either side, with acoustic baffles between the blower and rads to reduce noise. The case is a Chenbro 4u deep Rackmount, still deciding on the pump(s), I have a few in hand. The box is meant to serve 3 or 4 computers so I am need to go heavy on the rads. Most likely 2 120.3s. I am looking for suggestions on them. Air resistance is not much of an issue as the blower should be easily push over 11 M³/ min at a reduced speed through a single thermochill type core, more through 2 of them. I have about 21 x 6.5" (53 x 16.5cm) clear space on either side of the case. So mostly looking for the most fin area and thickness "should" not be an issue. It would be nice if manufactures provided info on fin spacing and actual depth....googled for a while found nothing... Also wondering about the jet size on G4's I want to include an inline filter and I need to specify the screen size but would rather not drain my existing rig to measure them. Thanks for any advice, JR Last edited by jlrii; 01-02-2005 at 12:36 PM. Reason: resize image

01-02-2005, 01:24 PM	#2
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	That's a big one (8 1/4"?!?). How much did it run you? __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

01-02-2005, 02:24 PM	#3
jlrii Cooling Savant Join Date: Feb 2004 Location: Massachusetts, USA Posts: 158	From all that I've read using a large blower at reduced speed is the way to go for reduced noise. From BillA's review it looks like moving 4.3 lpm of air across a single 120.3 produces about 62.3 pa, so two of them should be about half that or about 31 pa. At that pressure it should be able to move just about 480 cfm CFM, way more than needed. So I hope to run @ 42% speed and get 200 cfm out of it as CFM1/CFM2 = RPM1/RPM2. (tho it will be fun to crank it up and watch the papers fly). It cost 63.58USD From here. I havn't run it yet to see how loud it is, the box will include a 115v speed control to tone it down. I am hoping with its sheer size I can run it pretty slow and hopefully quietly for everyday use. It has a PSC motor so it should not heat up to badly or stall at lower speeds. Last edited by jlrii; 01-02-2005 at 02:38 PM. Reason: content

01-02-2005, 03:05 PM	#4
jlrii Cooling Savant Join Date: Feb 2004 Location: Massachusetts, USA Posts: 158	I havnt done the math yet to see how loud it may be...I will have to physically measure rpm to do that as it is not shown on the fan....may be 2550 rpm it saya 2550min-1 ???? EBM's german site seems to list fan speeds like that from what I can tell. 3. Acoustic Noise Cooling electronic systems by air is a common practice throughout the industry. In cases where the system is cooled by forced convection, a blower or a fan is used as the air mover. The size of the air mover is a function of the cooling requirements for the system and the individual components. Associated with the air movers is the acoustic noise that is generated as the result of the air moving within the system. If we look at the sound power level (Lw) for a blower, we can see the role air velocity plays in the noise generated by a blower, (reference 3) Lw=logh(G / D3N)+2logP+logG+12 (8) Likewise, LW for the small axial-flow fans is given by the following equation: Lw=3.71logVt+0.96logG-10.8 (9) where, G = the volumetric flowrate N = the impeller speed in rpm D = the impeller diameter P = static pressure drop Vt = the tip speed of the impeller Last edited by jlrii; 01-02-2005 at 04:24 PM.

01-02-2005, 05:00 PM	#5
MaxxxRacer Cooling Savant Join Date: Sep 2004 Location: Los Angeles, Ca Posts: 310	now that my friends is a fan.... wonder what the nosie levels on that sucker are.. __________________ Excuse me, I believe you have my stapler.

01-03-2005, 12:17 AM	#6
Kobuchi Cooling Savant Join Date: Jan 2003 Location: BC, Canada Posts: 313	That, is not a blower. Nice and compact. Wow it looks cool. And low noise without any housing.

01-03-2005, 05:21 AM	#7
jlrii Cooling Savant Join Date: Feb 2004 Location: Massachusetts, USA Posts: 158	Well yeah, actually a motorized impeller. Not exactly quiet at full speed....500CFM=70dba. hopefully a lot quieter than that when slowed down 200CFM=?DBA.

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