when i did a comparison of the airflow for this shopvac
versus this blower on the back of my router table the shopbox airflow was less than half as much
it's less than i thought it would be and i figured maybe it's the hose
so i've got my shop vac with a standard hose on it to a box with an opening 12
centimeters in diameter and then i can measure the airflow by measuring the air speed into it
so we got 2.2 meters per second and 2.2 meters per second works out to 52 cfm now
with the blue hose that i normally use which is a fair bit longer but also a little bit wider
let's call that 2.9 so even though this hose is longer i get a bit more airflow through it
and that's because this hose is a fair bit thicker it's actually a pool hose let's try this two and a
half inch dust collector hose which unfortunately doesn't quite fit on here but i made an
adapter and that increased the airflow once again
let's try it with no hose 91 cfm so the standard hose nearly cuts the airflow in half
since my two and a half inch hose did so well i've now got all my two and a half inch hoses hooked up
30 feet so as it turns out those three hoses together still have less air resistance than
this one hose here i get 64 cfm versus 52 cfm with a standard hose and i know some people like long
wind-up hoses with a shop vac i don't have one of those but here it is with a central vac hose which
is about the same length a way a bit longer than my two and a half inch hose i just tested with
and with that hose i get the smallest amount of all less than a standard hose
and uh just over half of what i get with the same length of two and a half inch hose
okay now let's test that against a cheap one horsepower dust collector
that's about 320 cfm and with a two and a half inch hose and now with a long central vac hose
and my airflow is so low this thing doesn't even give me a reading so what's interesting is with
a two and a half inch hose i had 81 cfm with the shopvac 91 with a dust collector but as soon as
i went to 20 foot hose i went from 74 here to 57 here so with a longer hose the vacuum cleaner did
better and that's because even though this can do way more cfm it has less pressure on there
so we can see here this dust collector gives us about 18 centimeters worth of suction now
i know the shop vac would just suck all that water straight out so i have to change my arrangement of
it so i hooked up the small hose to the shop vac hose and up and down into this container
and i'm getting about 107 centimeters of suction that's almost six times what this one can do
and that's why shopvac is able to deal with these narrow hoses even long ones but of
course it does benefit from having a bigger hose whereas this can deliver a huge amount of cfm
but not through a small hose and for comparison i just tested it with my homemade dust collector and
it delivers more cfm than the shopvac and more suction pressure than the dust collector but
less cfm to this one and less pressure than this one so it's kind of part way between a shop vac
and a dust collector and what i've got here right now is actually i tried bypassing the cyclone so
i'm just sucking straight into the filter box here no cyclone and bypassing a cyclone
makes about as much difference as taking off one of these 10 foot long two and a half inch hoses so
the cyclone offers considerable air resistance for dust collectors but compared to what a shop vac
deals with it's much less air resistant say than just one of these hoses here so sucking through
a cyclone for a shop vac is a relatively small penalty but for a dust collector like this it
actually cuts the no hose airflow in half because it just has a lot of air resistance and with the
relatively low pressure of this dust collector you really don't want to put a cyclone in line
because that will really cut down on the airflow so i hope you found these experiments useful
i certainly always enjoy them just now i have to put all my dust collection stuff back together you