roombacurious
Established Member
I was wondering, is there anyone from Camvac watching this forum? It's just that I was browsing their web site today and I found some of their claims so hard to swallow I'd love to have a chat with them (yes, I know, I can always call them :roll: )
In particular:
1) Filtration: They claim their filters are good down to 0.5 microns. They may well be, no dispute there. However their best triple motor 3300w unit according to their specs has a flow of about 330cfm - 220 for the double motor and 110 for the single. This is hardly enough for chip extraction (see Bill Pentz's site) which requires about 350cfm. Camvacs don't seem to suck enough air ever for descent chip extraction, let alone fine dust! For fine dust you need about 1000cfm... So, the filters may be great but their potential is wasted as these vacuums can't move enough air to catch the fine dust these filters are supposed to deal with. From an air quality point of view it would probably have been the same even if the filters were 5 micron rated instead of 0.5.
2) NVT design: That's utter nonsense. The neutral vane design applies to cyclones and Camvacs are not cyclones.
Basic theory: A cyclone works by separating particles in an air vortex. At the bottom of the vortex (where air flow is reversed) gravity draws particles into the trash can. The reason properly designed cyclones are so tall is that they need to have enough height to accommodate the whole vortex. If this is not the case then the bottom of the vortex is in the trash can lifting all the rubbish up and through the impeller. This defeats the purpose of having a cyclone in the first place.
To come back to neutral vanes, the idea is that you adjust the air inlet length and position so that you avoid turbulence in the cyclone. This makes sense only if you have a properly designed cyclone and want to further improve separation by reducing turbulence. Camvacs, a) are not cyclones, b) their cans are so short it's impossible for anything to settle at the bottom with the motor on.
Practical example: I've been experimenting with a garden vac and a trash can, very roughly imitating Camvac's design (garden vac on top of the lid sucking air through a hole in the lid, inlet on the side). My garden vac has an 1800w motor and moves 350cfm according to specs. I've used no filters to avoid reducing the air flow and was venting outside. Well, with a 100mm inlet the full size 80lt trash can was constantly being scoured clean, all the dust getting sucked up and sprayed outside. What does this mean? Just that if you want 350cfm at high pressures (just as Camvac does) you need something bigger than a trash can if you want anything to settle at the bottom.
Camvac have a good reputation for reliability and this cannot be denied. But I feel their advertising and presentation of their products is very misleading. What they really are is plain vacuum cleaners with good filters, no more, no less. They don't seem to have enough air flow even for chip collection let alone taking advantage of the 0.5 micron filtration. The so-called NVT design makes no sense and seems just a marketing trick.
As some of you already know I don't work for any competitors or have a grudge against Camvac. In fact competitive machines such as Axminster's WV series are of similar design and what I've mentioned applies to them too. I'm sure Camvacs are well made machines that last for years. However the manufacturer should be honest about what they sell and woodworkers should know what they're really buying.
I'm no engineer, I'm just a doctor who's done a bit of research and experimentation. So Camvac, if you're reading, please get one of your engineers to help me out here: where am I wrong and most importantly, why should I pay £400 for one of your vacs? :?:
In particular:
1) Filtration: They claim their filters are good down to 0.5 microns. They may well be, no dispute there. However their best triple motor 3300w unit according to their specs has a flow of about 330cfm - 220 for the double motor and 110 for the single. This is hardly enough for chip extraction (see Bill Pentz's site) which requires about 350cfm. Camvacs don't seem to suck enough air ever for descent chip extraction, let alone fine dust! For fine dust you need about 1000cfm... So, the filters may be great but their potential is wasted as these vacuums can't move enough air to catch the fine dust these filters are supposed to deal with. From an air quality point of view it would probably have been the same even if the filters were 5 micron rated instead of 0.5.
2) NVT design: That's utter nonsense. The neutral vane design applies to cyclones and Camvacs are not cyclones.
Basic theory: A cyclone works by separating particles in an air vortex. At the bottom of the vortex (where air flow is reversed) gravity draws particles into the trash can. The reason properly designed cyclones are so tall is that they need to have enough height to accommodate the whole vortex. If this is not the case then the bottom of the vortex is in the trash can lifting all the rubbish up and through the impeller. This defeats the purpose of having a cyclone in the first place.
To come back to neutral vanes, the idea is that you adjust the air inlet length and position so that you avoid turbulence in the cyclone. This makes sense only if you have a properly designed cyclone and want to further improve separation by reducing turbulence. Camvacs, a) are not cyclones, b) their cans are so short it's impossible for anything to settle at the bottom with the motor on.
Practical example: I've been experimenting with a garden vac and a trash can, very roughly imitating Camvac's design (garden vac on top of the lid sucking air through a hole in the lid, inlet on the side). My garden vac has an 1800w motor and moves 350cfm according to specs. I've used no filters to avoid reducing the air flow and was venting outside. Well, with a 100mm inlet the full size 80lt trash can was constantly being scoured clean, all the dust getting sucked up and sprayed outside. What does this mean? Just that if you want 350cfm at high pressures (just as Camvac does) you need something bigger than a trash can if you want anything to settle at the bottom.
Camvac have a good reputation for reliability and this cannot be denied. But I feel their advertising and presentation of their products is very misleading. What they really are is plain vacuum cleaners with good filters, no more, no less. They don't seem to have enough air flow even for chip collection let alone taking advantage of the 0.5 micron filtration. The so-called NVT design makes no sense and seems just a marketing trick.
As some of you already know I don't work for any competitors or have a grudge against Camvac. In fact competitive machines such as Axminster's WV series are of similar design and what I've mentioned applies to them too. I'm sure Camvacs are well made machines that last for years. However the manufacturer should be honest about what they sell and woodworkers should know what they're really buying.
I'm no engineer, I'm just a doctor who's done a bit of research and experimentation. So Camvac, if you're reading, please get one of your engineers to help me out here: where am I wrong and most importantly, why should I pay £400 for one of your vacs? :?:
