Thread: Am I on the right track?

I feel you are on the right track, asking the right questions.

What is the maximum ampere's that can be drawn from you supply?

Cheers Barry

Originally Posted by JimmyD

I've read a lot about the need for a motor larger than 3HP to turn a big 15" or 16" impeller. Will the performance of the Laguna machine therefore be limited by its 3HP single-phase motor?

I don’t trust motor power ratings - my generic 3HP dust extractor uses half that. I’m using 6” duct with one 90° bend and about 6m of duct, so it should be pretty open and therefore draw near its rated power.

Basically I’d say a Laguna 3HP will be more powerful than a generic 3HP motor with a 12” impeller.

Originally Posted by mannum3

I feel you are on the right track, asking the right questions.

What is the maximum ampere's that can be drawn from you supply?

Cheers Barry

Thanks Barry. First thing I did when I bought the property was ran a fat enough cable (16mm2 I think) to the workshop to make the full single phase supply available. I don’t know exactly what the figure is but I believe it’s somewhere between 60 and 80 amps.

Currently I have the two biggest tools (table saw and thicknesser) on their own separate 20amp circuits. I expect I’d be running another dedicated circuit for the dust extractor.

Originally Posted by Colin62

I don’t trust motor power ratings - my generic 3HP dust extractor uses half that. I’m using 6” duct with one 90° bend and about 6m of duct, so it should be pretty open and therefore draw near its rated power.

Basically I’d say a Laguna 3HP will be more powerful than a generic 3HP motor with a 12” impeller.

Thanks Colin, that’s helpful.

Jimmy you will find that it won't take long before your shop becomes too small so putting the DC outside is a good idea and the noise outside is a bonus.

The Laguna while having a bigger diameter impeller it may also be thinner in order for the motor to spin it. I doubt the motor/impeller is any different than the North American machines to make up for the 50/60 hertz difference so would actually move less air than ours by 20%. Comparing the specs from both countries should tell you if there is a difference and if they adjusted the specifications to reflect. They are a short cone therefore not as efficient at separation as the CV1800/max. Not as big a deal because you are venting outside.

The Clear Vue Cyclones had the same current frequency issues when introduced in Australia and that's why they were fitted with 3 phase motors and the VFDs. It let them be spun to the same speeds as ours gaining back the 20% of airflow. You can even run them at a slightly faster speed for a little more flow. Chris Parks was the Aussie that brought them in and he can tell you more about overclocking them. Going to the CV Max with the 16" impeller would give you even more flow but at the added expense of bigger ducting. I believe you can also order the CV1800 with the bigger impeller as a compromise but don't know how much of an added benefit you would get.

Good on you for researching before diving in.

Pete

The louvred wall exhaust fan you link to claims 800 L/s which works out to about 1600 CFM but I seriously doubt it can do that especially with louvres in front of it. It might do half that. I reckon you would need to get at least two of these for your size shed, and remove the louvres.

Location of wall fans on the wall opposite the major shed openings is indeed the way to go.

One reason why the laguna can safely use a 3HP motor is that the "older design" means it is quite restrictive to flow which self limits the motor current.
Interesting to see the specs say the following

Airflow Realistic	2209 m3/hr (1299 cfm)
Airflow Standard Measure	3831 m3/hour (2253 cfm)

1250 CFM is about what my 3HP DC with 13" impeller can pull through an open 6" duct at about 8.5"WC.
A conventional cyclones will lose about 4.5" of WC so that means the Cflux (13.5") impeller has to be generating ~13" of WC. Somehow I doubt it can do this at 50Hz.

The other thing that confuses me is the sawdust collector drum claims to be 200L but it looks much smaller than that to me.
The flat collection bag spec is 38 x 38" when flat which converts into a bag volume of 79L?
If so, that is pretty small and would be most annoying give the drum should be emptied when ~2/3s full.

If you get one and vent it outside I would remove the filter as all that does is restrict the flow - BUT make sure you measure the motor current to see that it is not too high or long term you will damage the motor

Originally Posted by QC Inspector

Jimmy you will find that it won't take long before your shop becomes too small so putting the DC outside is a good idea and the noise outside is a bonus.

Thanks for the info Pete! I’ve long since run up against my space limitations, the current layout was only made workable after I made the decision to get rid of absolutely anything not critical for daily production. Now I’ve got JUST enough room to drag a little 2HP dusty from machine to machine. Have to open the roller doors put anything longer than 1200mm though the thicknesser.

It’ll definitely be a win to get the DC out of the shed, along with the jumble of flex pipe cluttering up off the floor.

Originally Posted by QC Inspector

The Laguna while having a bigger diameter impeller it may also be thinner in order for the motor to spin it. I doubt the motor/impeller is any different than the North American machines to make up for the 50/60 hertz difference so would actually move less air than ours by 20%. Comparing the specs from both countries should tell you if there is a difference and if they adjusted the specifications to reflect. They are a short cone therefore not as efficient at separation as the CV1800/max. Not as big a deal because you are venting outside.

The Clear Vue Cyclones had the same current frequency issues when introduced in Australia and that's why they were fitted with 3 phase motors and the VFDs. It let them be spun to the same speeds as ours gaining back the 20% of airflow. You can even run them at a slightly faster speed for a little more flow. Chris Parks was the Aussie that brought them in and he can tell you more about overclocking them. Going to the CV Max with the 16" impeller would give you even more flow but at the added expense of bigger ducting. I believe you can also order the CV1800 with the bigger impeller as a compromise but don't know how much of an added benefit you would get.

Good on you for researching before diving in.

Pete

This is great info, thanks. It’s sounding more like a clearvue is the option with fewest compromises at that price bracket.


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Originally Posted by BobL

The louvred wall exhaust fan you link to claims 800 L/s which works out to about 1600 CFM but I seriously doubt it can do that especially with louvres in front of it. It might do half that. I reckon you would need to get at least two of these for your size shed, and remove the louvres.

Thanks for this Bob. You say performance might be expected to be half of the manufacturers claim - would you hazard a guess as to how much of this drop caused by to the louvres themselves vs the over-optimistic claimed specs? If I remove them I’ll have to find some alternative way to stop vermin entering. If it’s just a matter of adding a third fan to make up the difference it might end up cheaper in the long run in time saved.

Originally Posted by BobL

1250 CFM is about what my 3HP DC with 13" impeller can pull through an open 6" duct at about 8.5"WC.
A conventional cyclones will lose about 4.5" of WC so that means the Cflux (13.5") impeller has to be generating ~13" of WC. Somehow I doubt it can do this at 50Hz.

That’s very helpful. It seems like the extra 20%-30% cost for the CV is well worth it if there’s 20% performance gain.

Originally Posted by JimmyD

Thanks for this Bob. You say performance might be expected to be half of the manufacturers claim - would you hazard a guess as to how much of this drop caused by to the louvres themselves vs the over-optimistic claimed specs? If I remove them I’ll have to find some alternative way to stop vermin entering. If it’s just a matter of adding a third fan to make up the difference it might end up cheaper in the long run in time saved.

Hard to tell but louvre losses could be up to 20%.

I know its a bit of a PITA but something like a simple hopper door/opening might be a way to prevent the vermin getting in.
The door/opening can be located on the inlet side.

A third fan is indeed an option but bear in mind that @ 67dB , the noise on those fans will add up compared to the Hydroponic type fans (12" 55db) which are very quiet.
2 of the 67 dB fans adds up to 70db, 3 fans is 72 dB
2 of the 55 dB fans = 58dB
Doesn't sound like much but over time that is a big difference and becomes very irritating.

Removing the louvres will make them quieter.

FWIW I have two Ventilation fans one (1200 CFM) is above my WW bench and the other (1600CFM) vents my Welding/spray booth and both act as general shed ventilators. The smaller fan is a 3P fan on a cheap VFD so I can overclock it a bit up to about 1400 CFM.
At full speed the smaller one is 62dB (at 1m from fan) and the bigger one is 72 DB but I usually only run at full speed when certain machinery is running. For general ventilation typically they run at 2/3rd speed which keeps the noise down.

Just as bad as the fan noise is the air rush noise from the extraction system - that's one way you know its really working. That's a major benefit of using a 3P motor and a VFD on the DC. I often run mine at 40Hz so's I don't have to put up with the noise.

That’s very helpful. It seems like the extra 20%-30% cost for the CV is well worth it if there’s 20% performance gain.

The CV will be more work to install but I can't fault its performance.

Thanks Bob. I’ll keep your point about the sound level in mind. I can see some quieter options are available but of course at a higher price!

I just want to thank everyone for their help so far. The process of building the outdoor enclosure, acquiring/installing a cyclone and running the duct will be somewhat lengthy. In the meantime I'm still in the workshop most days - so I'm going to focus on getting some forced ventilation in ASAP to give some quick improvement in air quality while I work to get the DC happening.

I'll take Bob's advice RE using quieter centrifugal hydroponic fans. If I was aiming for 20 air changes per hour, I believe I need a bit around 3000m3/h fan capacity.

Looking at the offerings from the Ebay seller mentioned in earlier threads, I can see that 3 x 10" fans would equate 2900m3/h... would love to get away with only installing two fans, but 2 x 12" only gives 2400m3/h, which is around 15 or 16 changes per hour.

Screen Shot 2021-03-30 at 1.12.41 pm.png

Of course, that's assuming their air flow figures can be trusted... perhaps it's better to go 3x10" (or 3x12") to be on the safe side.

Next is working out how to weatherproof the outside of the duct without resorting to louvers. Would a hood of the following design work without being too restrictive of airflow? I'd leave out the mesh screen from the opening of the duct; I'm just trying to stop the (sometimes-near-horizontal) subtropical rains.

Screen Shot 2021-03-30 at 2.00.27 pm.jpg

I have seen lots of commercial chicken barns with discharge hoods similar to this. You can knock one up using quarter rounds of plywood for the sides and sheet metal (roof flashing) nailed on for the rounded over part.

Exhaust Fan Weather Hood

Pete

Originally Posted by QC Inspector

I have seen lots of commercial chicken barns with discharge hoods similar to this. You can knock one up using quarter rounds of plywood for the sides and sheet metal (roof flashing) nailed on for the rounded over part.

Exhaust Fan Weather Hood

Pete

Thanks Pete, sounds like a good, simple way to do it.

You're welcome. Forgot to mention the obvious. You can cover the bottom with hardware cloth (1cm x 1cm wire mesh) or chicken wire to keep the wildlife out.

Pete