Thread: Shop Vac hose diameter - does it matter?

Absolutely

I would suggest that, if the inlet into the vacuum chamber is still 1-1/4 inch, the line will only provide 1-1/4 inch performance.
If you put a device like a Dust Deputy or ClearVue Mini in front of your shop vac, then you will be pulling mainly clean air into the vacuum. Unless you overfill the cyclone, both the vacuum and cyclone will always operate at a high level of efficiency.
Or, just get a 2 or 2 1/2 inch shop vac.

Don

Although they both perform their basic functions by moving air, dustys and vacuums are hard to compare with each other, particularly if you try to apply the rules applicable to one to the other.

With a dusty,the aim is to move high volumes of air and keep it moving at a fast enough rate to entrain the dust. Too thin a duct and the volume of air drops too low to be effective. Too wide a duct and the speed drops to the point that the dust is no longer entrained.

Vacuums move much lower volumes of air and as I understand it they rely more on pressure than volume. I agree with Don Burch that there is little point in putting on a bigger hose than the smallest choke point. Vacs are less susceptible to loss of efficiency over long runs of ducting/hose, which is good news for your maximum 3 metres of hose. You could even consider making that run longer and placing the vacuum outside the shed as they asre often dirty things that put more fine dust into the air than they take out. Cyclones and other separators also work well on vacuums.

Don and Doug, the inlet port into the vacuum is about 2" to 2-1/2", I haven't measured it, but the hose Ryobi provides narrows to 1-1/4". I also use one of those Chinese dust deputy clones and it works brilliantly, its ports are also over 2". So given what you've said I should go for the biggest hose that matches the inlet port on my shop vac?

Originally Posted by barri

I also use one of those Chinese dust deputy clones and it works brilliantly, its ports are also over 2". So given what you've said I should go for the biggest hose that matches the inlet port on my shop vac?

If it is pulling sufficient air through the 2" ports on the cyclone using the thinner hose, worst case scenario is that it will do as well with the wider hose. Best case scenario is much better performance.

I understand dusty's better than I understand vacs but you have nothing to lose and everything to gain by trying. Either way consider what I said about getting the vacuum outside the shed.

I'll try the bigger hoses and report back and unless I can build a sound proof enclosure for the shop vac to keep it outside, which makes sense, my neighbors might ring the police. The vac is loud.

Shop vacs are designed with fans/impellers that are almost @ full flow with their standard hose attached.
If that is a 28 mm hose then using a 50 mm hose of the same length or shorter won't make much difference as the impeller will not spin much faster

Where it will make a difference is when using longer than a standard hoses or ducting.
Using a longer 28 mm hose will reduce the flow signficantly whereas the 50mm hose will reduce it much less.

If you can hear a significant change in the motor pitch when you swap hoses this indicates the hose is having an effect on flow.

Remember you have to compare the change in motor pitch of the 28 mm hose with the 50 mm hose. Both hoses will change the sound pitch - it's the difference between the sound pitches made by the two hoses that matters.

If you have a manometer you can measure this effect more accurately. Remember Shop vacs generate around 30" of Water Column vacuum so you will need a manometer that is a least a metre tall or the vac will suck the manometer fluid into the vac!

My shop vac takes a 50mm hose on the inlet and outlet. If you look at the standard hose (38mm) the fitting to the machine is actually a reducer. I used a plumbing fitting for my 50mm hose.

Originally Posted by barri

I'll try the bigger hoses and report back .

The outlet on my shop vac is 2-1/2" (63mm) so I replaced all hoses with that size and there is a definite improvement. So the whole exercise was worthwhile. I bought some of these https://www.timbecon.com.au/extracti...63mm-connector and they are not only easy to thread onto the hoses but provide a great friction fit on some of my tools eg the fence on my router table and the outlet on my disc/belt sander. A few adapters for my other tools and I now have a good setup, however when using one of those adapters which reduces the 2-1/2" hose to 1-1/4", the hoses drastically shrink under the vacuum from the cyclone and bucket. Its as if I'm completely covering the hose.