Thread: What speed are you running your CV1800 at: 50Hz, 60Hz or 70Hz?

Neil,

I am running my 1800 at 60 Hz to get the additional air flow. If I ran it at 50 Hz I wouldn't get the great dust extraction I am getting at 60 Hz.

If I had my time again I'd buy a CV MAX and run it at 50 Hz ... lots of air flow and less noise.

Ronboult brought his instruments to my shed and got the following figures at 60 Hz (figures integrated to allow for losses in the 12-15 mm beside the duct walls):
Drop Saw ........4,850 FPM and 906 CFM
Drill Press ....... 5,200 FPM and 971 CFM
Drum Sander ... 4,550 FPM and 850 CFM
Band Saw ....... 4,300 FPM and 803 CFM
Table Saw ...... 5,100 FPM and 952 CFM
Linisher .......... 4,650 FPM and 868 CFM

Bill Pentz says we need about 800 CFM to meet OHS standards.

My figures demonstrate that BobL was right. Most of the losses are at the machines themselves, especially ports and hoods. It really pays to open out all ports to 150 mm and to ensure clean air flow into and through machines.

Further details here ... Making 150mm DC ports for workshop machines

Hi Neil,

Mannum Men's shed 50 Hertz 72db @ 2M

An interesting question which Neil and I have discussed off forum and some background to Bill Pentz's and Clearvue's thinking which I have laid out before in this forum but just in case some might have missed it I will do it again with a bit more added. There was discussion on this forum about importing CV's some years before it happened and the VFD's we know today were not the consumer items they are now so any country outside the US that wanted to import a CV was going to have to run the motor slower due to 50hz in most countries. The Max was developed to flow at 50hz what the 1800 did at 60hz and if the question was raised today the Max might not have been made. Now it would be a question of 3 phase and wind up the speed on the VFD. I will confess now that this option never occurred to me when I was selling them because I did not fully understand the versatility the VFD gave us. Running an 1800 at under 60hz does not give optimum fine dust capture according to Bill Pentz.

In answer to Neil's question I ran noise tests just now with some surprising findings. The tests were done with one 150mm BG open as would be the case in most operations.

Internal Measurements:

70hz - 69db
60hz - 66db
50hz - 69db!
40hz - 57db

External Measurements:

70hz - 75db
60hz - 63db
50hz - 63db
40hz - 60db

The anomaly between 50 & 60 internal I can't explain and I did repeat it and got the same answer. The noise appears by the ear method to drop but the meter says otherwise and measuring noise is about the same as chasing cats.

I don't really understand the problem with the extra noise from a higher speed because if the cyclone is running then a noisier machine is running and I can't hear the cyclone above that machine except if it was a drill press and I am wearing ear defenders anyway. As long as the exhaust does not impact any neighbours etc then let it rip. One drawback I have found is the collection drum, I use a 205L plastic drum and until I would the speed up I had no issues but no it has started to collapse which is a bit of a pain in the neck.

I don't have a ClearVue but I do have a 4HP 3P on a VFD extractor and run it at different speeds depending on what I'm doing. Mind you I have a dust/particle counter running constantly so I can monitor what is going on.

The reason for variable speeds is I hate the excessive noise at higher speeds. The noise is good in one way in that it tells me there's a lot of air going through the system when I really need it.

As well as speed potentiometer (can set any speed below 65Hz) I have a 3 position switch for 40, 50 and 60Hz so I can quickly switch between speeds.

40Hz operations are very quiet so I use this for general ventilation, the drill press, and things like multiple small bandsaw cuts, I also use this when cooling down hot PVC pieces when making Bell mouth hoods on the WW lathe.

50Hz is for small cuts on the TS, standard lathe work and small stuff on the belt sanders.

60Hz (have to wear ear muffs for this) is for big pieces on most machinery.

I don't let mine run at 70Hz as the motor reaches the current limit programmed by me on the VFD at about 67Hz. Anyway the air rush noise at 65Hz is dreadful which is why I rarely used that speed.

Can we confine this to just the 1800 please. Running the Max at 70hz simply doesn't work in my experience using the standard VFD and when I tried it the VFD spat the dummy after a short period.

Originally Posted by mannum3

Hi Neil,

Mannum Men's shed 50 Hertz 72db @ 2M

Why so low?

Originally Posted by John Samuel

Neil,

I am running my 1800 at 60 Hz to get the additional air flow. If I ran it at 50 Hz I wouldn't get the great dust extraction I am getting at 60 Hz.

If I had my time again I'd buy a CV MAX and run it at 50 Hz ... lots of air flow and less noise.

Ronboult brought his instruments to my shed and got the following figures at 60 Hz (figures integrated to allow for losses in the 12-15 mm beside the duct walls):
Drop Saw ........4,850 FPM and 906 CFM
Drill Press ....... 5,200 FPM and 971 CFM
Drum Sander ... 4,550 FPM and 850 CFM
Band Saw ....... 4,300 FPM and 803 CFM
Table Saw ...... 5,100 FPM and 952 CFM
Linisher .......... 4,650 FPM and 868 CFM

Bill Pentz says we need about 800 CFM to meet OHS standards.

My figures demonstrate that BobL was right. Most of the losses are at the machines themselves, especially ports and hoods. It really pays to open out all ports to 150 mm and to ensure clean air flow into and through machines.

Further details here ... Making 150mm DC ports for workshop machines

Many thanks, John.

Very useful to have that FPM & CFM data for those machines with 60Hz.

I looked at the CV-Max for the Men's Shed, but the issue there is that we have 6" ducting and the Max needs a 7" or 8" main duct to provide any additional benefit other than being quieter at 50Hz.

I did a back of the envelope costing of upgrading the main duct and fittings to 8" (225mm) and that was going to cost over $2k for our system, so decided to stay with the existing 6" ducting and consider running two separate DEs on 6" ducting.... no decision there yet.

Originally Posted by mannum3

Hi Neil,

Mannum Men's shed 50 Hertz 72db @ 2M

Thanks for that M3. That sure is quiet!

What acoustic dampening have you done to get that? Apologies if you have already posted on that already somewhere, if so, a reference to that would be appreciated.

Have you had any issues from your membership with noise level if you have tried running it at 60Hz?

I've taken some dB readings of the noise levels from some of our working machines, like the following. As Chris P points out, most of our machines will be louder than what I expect from the CV1800 at 60Hz.

Nose reading location/conditions	dB (A)
Radial arm ,saw - at 1m - while cutting	118.9
Radial arm saw - at 2m - while cutting	107.6
Radial arm saw - at 3m - while cutting	103.5
Radial arm saw - at 5m in next W/S while cutting	98.2
Radial arm saw - at 1m - running/not cutting	83.3

Originally Posted by BobL

I don't have a ClearVue but I do have a 4HP 3P on a VFD extractor and run it at different speeds depending on what I'm doing. Mind you I have a dust/particle counter running constantly so I can monitor what is going on.

The reason for variable speeds is I hate the excessive noise at higher speeds. The noise is good in one way in that it tells me there's a lot of air going through the system when I really need it.

As well as speed potentiometer (can set any speed below 65Hz) I have a 3 position switch for 40, 50 and 60Hz so I can quickly switch between speeds.

40Hz operations are very quiet so I use this for general ventilation, the drill press, and things like multiple small bandsaw cuts, I also use this when cooling down hot PVC pieces when making Bell mouth hoods on the WW lathe.

50Hz is for small cuts on the TS, standard lathe work and small stuff on the belt sanders.

60Hz (have to wear ear muffs for this) is for big pieces on most machinery.

I don't let mine run at 70Hz as the motor reaches the current limit programmed by me on the VFD at about 67Hz. Anyway the air rush noise at 65Hz is dreadful which is why I rarely used that speed.

Many thanks for those details Bob.

I'm not sure if I can get the Men at the Shed to tweak the VFD up and down to that extent. It has been hard enough to get them all to open and close blast gates. Maybe two speeds... slow (50Hz) and fast (60Hz) with a machine chart next to the VFD. Will definitely have to set an upper limit for the fumble fingered!

Originally Posted by Chris Parks

An interesting question which Neil and I have discussed off forum and some background to Bill Pentz's and Clearvue's thinking which I have laid out before in this forum but just in case some might have missed it I will do it again with a bit more added. There was discussion on this forum about importing CV's some years before it happened and the VFD's we know today were not the consumer items they are now so any country outside the US that wanted to import a CV was going to have to run the motor slower due to 50hz in most countries. The Max was developed to flow at 50hz what the 1800 did at 60hz and if the question was raised today the Max might not have been made. Now it would be a question of 3 phase and wind up the speed on the VFD. I will confess now that this option never occurred to me when I was selling them because I did not fully understand the versatility the VFD gave us. Running an 1800 at under 60hz does not give optimum fine dust capture according to Bill Pentz.

In answer to Neil's question I ran noise tests just now with some surprising findings. The tests were done with one 150mm BG open as would be the case in most operations.

Internal Measurements:

70hz - 69db
60hz - 66db
50hz - 69db!
40hz - 57db

External Measurements:

70hz - 75db
60hz - 63db
50hz - 63db
40hz - 60db

The anomaly between 50 & 60 internal I can't explain and I did repeat it and got the same answer. The noise appears by the ear method to drop but the meter says otherwise and measuring noise is about the same as chasing cats.

I don't really understand the problem with the extra noise from a higher speed because if the cyclone is running then a noisier machine is running and I can't hear the cyclone above that machine except if it was a drill press and I am wearing ear defenders anyway. As long as the exhaust does not impact any neighbours etc then let it rip. One drawback I have found is the collection drum, I use a 205L plastic drum and until I would the speed up I had no issues but no it has started to collapse which is a bit of a pain in the neck.

Many thanks Chris for those detailed readings and for your help off forum.

I know that you have done a lot of work on your acoustic control for both inside and outside your workshop. Those numbers for 60Hz give me confidence that with adequate acoustic dampening the noise levels won't be an issue.

From your data there appears to be no benefit from a noise perspective from dropping back to 50Hz, other than perhaps saving a few kWhrs.

Anyway, some PM2.5 μm/m³ reading will confirm the level of dust control at both 50 and 60Hz after implementation.

Originally Posted by NeilS

Many thanks for those details Bob.

I'm not sure if I can get the Men at the Shed to tweak the VFD up and down to that extent. It has been hard enough to get them all to open and close blast gates. Maybe two speeds... slow (50Hz) and fast (60Hz) with a machine chart next to the VFD. Will definitely have to set an upper limit for the fumble fingered!

Yep I agree. I couldn't get many of our blokes to even turn the DC on let lone change a speed.
At the mens shed I was a member of, only the supervisor could change the speed and he typically left it on 60Hz.
I would do the same because members would simply forget to switch it back up to where it was needed and that would let fine dust fill teh shed.


I realize this is not what your initial post was targeting but I add it for completeness
A lathe is an example of a machine that is much quieter than any high speed dust extraction noise.
My lathe with nothing on board runs at about 55db, and while sanding and light turning its 60-65dB,
The noise from the BMH is 72 db @ 40Hz, 78 dB at 59Hz and 85 dB at 60Hz and on top of that the air rush/whistling noise at 60Hz is highly irritating so I find I have to wear muffs if I want to turn at 60Hz. If all I'm doing is some light sanding the the air flow @ 40Hz is usually enough for short spindle work. If its a large object then I have to grin and wear them.

For my big sander and BS its not quite as clear cut but if I'm just sanding/sawing something small then 50Hz is plenty.

The simple answer in a Men's Shed which does work is to switch it on when the place is opened in the morning and switch it off at break time and end of day. If using our blast gate system the cyclone can be idled at a lower set speed or allowed to turn of and the next machine started will fire it back up.

Originally Posted by BobL

A lathe is an example of a machine that is much quieter than any high speed dust extraction noise. My lathe with nothing on board runs at about 55db, and while sanding and light turning its 60-65dB. The noise from the BMH is 72 db @ 40Hz, 78 dB at 59Hz and 85 dB at 60Hz and on top of that the air rush/whistling noise at 60Hz is highly irritating so I find I have to wear muffs if I want to turn at 60Hz. If all I'm doing is some light sanding the the air flow @ 40Hz is usually enough for short spindle work. If its a large object then I have to grin and wear them.

Useful info, thanks, Bob.

In my own workshop, where I'm mostly turning medium to large bowls and platters, the main culprit is sanding, which flings fine dust big time and would completely load up the air in the workshop if it weren't for the cyclone running and the bell mouth in close proximity to the piece.

If I remember correctly, I get closer to 90dB right at the bell mouth, so have always worn hearing protection myself. I have enough industrial deafness already without adding to it.

However, getting everyone at the Shed to wear hearing protection is another matter.

Originally Posted by NeilS

However, getting everyone at the Shed to wear hearing protection is another matter.

Reminds me of the member using a router I waved the SPL meter showing over 90dB in front of, and he said "S'ok I've taken my hearing aids out"