Thread: Double Dust Collectors in Parallel

I doubt it.

More info needed.
In stock or modified form?
US or Oz setting (50 or 60Hz)?
With or without filters?

I believe they are Grizzly brand 2 hp at 60 hz


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Don't know whether it's just the photo but those DE's look to be two different sizes and both choked down to a smaller size then the main duct at the inlet. No bags or filters so his claim of 1800 cfm is pretty meaningless anyway, even if it is correct.

second other posters thoughts.

Even if those numbers are legit, the motors won't last very long as they'll be drawing too much power.

Adding back pressure in the form of filter bags will instantly solve the above, but at the same time significantly cut the flow.

This description might help explain pumps in series and parallel.

Pumps in Parallel or Serial
Note there in no increase in static pressure from such as arrangement - just an increase in flow.
BUT
In practice two identical pumps in parallel usually end up pulling about 1.3-1.5x the flow of one pump albeit at a reduced pressure drop

A modified unrestricted 2HP impeller at 50Hz delivers about 1100 CFM.
At 60Hz it should deliver 20% more so 1320 CFM,
2 impellers should thus theoretically deliver 1716 to 1980 CFM
BUT
NB this is an unrestricted flow.

This fabulous unrestricted flow will die very quickly because of the limited pressure curves these small impellers generate.
This is demonstrated by the modified 2HP impeller at 50Hz that delivers 1100 CFM, dropping to 860 CFM with filters.
Any ducting, fittings, choked machines etc drop that even more.

Allowing for the 20% improvement from using 60Hz ,the flow from one modified 2HP DC with filters will then be 1032 CFM.
Because there are two impellers the flow reduction will be slightly less but not that much.
2 such DCs will should in practice deliver somewhere between 1350 - 1550 CFM.

However, at the pressures generated by those impellers, a 6" trunk line will still not carry much more than 1250 CFM
To get the larger flows a larger diameter trunk line will be required.
BUT
Remember (because their limited fan curve) as soon as any ducting, fittings, choked machines etc are added flows will drop.

In the end you simple won't get more than a 4HP machine with say a 15" impeller.
There's no getting around the need for a bigger impeller to keep delivering the flow rates that are required under restrictions.
The bigger impellers are going to have a superior fan curve so will cope better with greater restrictions from ducting, fittings, choked machines etc
This is why adding a cyclone to a small DC results is less flow and less dust collected at sound.