Ridgid Shop Vac Static Pressure #'s

[Randy Klein]

Just FYI:

In previous threads about shop vacs comparing Ridgid w/SNR vacs to Fein and Festool, the static pressure #'s for Ridgid were not listed on the website. I checked this morning and they are now listed:

WD1850
- Static Pressure : 53 In.
- Cubic Feet Per Minute (CFM) : 203 CFM

The pressure is significantly less than, but CFM more than, the Fein and Festool. Although I forget what that actually implies, I wanted to provide the update...

[Mike Marcade]

The higher static pressure can pull things through a smaller port opening (like a sander or a router). There is an inverse relationship between CFM and static pressure.

Therefore the Ridgid is probably not as good at dust collection through a small port opening as the Fein and Festool are, but better through a larger opening (like for general shop vac use)

[Phil Thien]

The higher static pressure can pull things through a smaller port opening (like a sander or a router). There is an inverse relationship between CFM and static pressure.

Therefore the Ridgid is probably not as good at dust collection through a small port opening as the Fein and Festool are, but better through a larger opening (like for general shop vac use)

While that is true, both vacs have enough static lift to handle our uses (1" hose on my PC sander, for example). But the higher CFM is nice for those of us trying to use the vac with portable tables saws and other tools that generate decent amounts of dust.

HOWEVER, that higher CFM comes at a price. The Ridgid, while certainly much quieter than previous vacs, is noiser than the Fein models.

[Randy Klein]

Is Static Pressure an inverse function of hose diameter? Could Ridgid's lower pressure be due to it having a wider hose than Festool/Fein?

[Mike Marcade]

Is Static Pressure an inverse function of hose diameter? Could Ridgid's lower pressure be due to it having a wider hose than Festool/Fein?

Aren't they both 2-1/4"?

[Randy Klein]

Aren't they both 2-1/4"?

Not sure, in my head, the Ridgid hose seems wider to me. Maybe I should actually go look it up...

[Brian Kerley]

Yes, that can be a part of it. With smaller diameters, your pressure goes up, but your flow rate goes down. But, there are ways around that by changing the motor, etc. (to tell you specifics I would have to bust out my fluid engineering/turbomachinery books, it's been a few years)

[Randy Klein]

Maybe I should actually go look it up...

Festool is 27mm so ~1-1/8
Fein is 2-1/4
Ridgid is 2-1/2 (but I think they list outside diameter) so probably more like 2-1/4.

[Mike Marcade]

Festool is 27mm so ~1-1/8
Fein is 2-1/4
Ridgid is 2-1/2 (but I think they list outside diameter) so probably more like 2-1/4.

From these dimensions and if they use a comparable length hose and if the manufacturer's advertised static pressure and cfm numbers were actually obtained with the hoses shipped with the product, then you can compare the Ridgid and Fein models as apples to apples. If you put a comparable hose on the Festool, I would guess it would perform pretty close to the Ridgid model, it all depends on the systems performance curve.