Tapered Hose on Miele Blizzard Bagless Canister Vac

[eurekaprince]

Our friend Ibaisaic Sensotronic in the UK has posted a new video demonstrating the Miele Blizzard canister vac. One strange thing with this vac is that the tapered hose needs to be installed with the wider end near the handle, rather than on the canister end.

Why would Miele do this? It’s seems to go against the idea that the airflow will speed up at the hose end, like a crevice tool, or a cyclone. The way the Blizzard hose is installed, it would seem prone to clogging as the hose could accomodate a large piece of debris at the handle end but get stuck in the narrower part of the hose closer to the canister.

Why would this design work better than those hoses that widen closer to the canister? Am I missing something here?

 

[blackheart]

Why?!

That's just dumb. It'd be less flexible around the handle end I would say it'd make it more prone to clogging but the debris needs to pass through it's typical 35mm inlets anways though I could see longer objects having more room to turn within the wider section though which could lead to clogging.

 

[luxflairguy]

No, that's NOT dumb!
Electrolux did this for years so that a clog near the handle end will go through the hose as it is larger at the machine end. Here is Lux's excact words "...Note that the hose is tapered, smaller at the handle end, larger at the end that goes into the cleaner. That is to prevent clogging." Lux's words.
Both of my Numatic machines: a Henry and a James have tapered hoses going the same direction from smaller at the handle and end larger at the machine end and I can assure you that is works! A small of say toilet paper or kleenex at the hose end clears instantly as the hose gets larger init's length. It makes total practical sense. If if fits in through the hose handle, it's guaranteed to get into the canister! Greg

 

[eurekaprince]

Hi Greg,

Thanks for your post. This Miele Blizzard has the opposite design: the wider end of the hose is at the handle, and the narrower end of the hose connects to the canister. I am wondering why this would work better than the other way around.

 

[blackheart]

Greg

You should have watched ibaisaic's video. I've owned 4 machines with tapered hoses. The miele's taper is reversed, narrower at the machine.

 

[luxflairguy]

Total ignorance..! G

 

[luxflairguy]

My opeing line came off the fingers wrong! It should have "That's just DUMB! Oppps! Old man here!

 

[blackheart]

Thinking

After giving it some thought the only reason I can only see one reason for the reversed taper.
Using the same body. If it were wider at the machine end the inlet and the piping leading to the bin would have to be as wide if not wider than the hose.

It's been my experience that tapered hoses offer performance advantages over uniform diameter ones at least if the uniform is equal to the narrowest diameter on the taper. I saw that on my lindhaus Aria, it originally had a tapered hose which allowed it to read 7.5 on the baird meter but a replacement non tapered 1.25" hose brought the meter down to 5.5. which is about a 12 CFM difference.

I'm quite curious if the reverse taper effects a machine's airflow as much as the standard. To test this i'll remove the cuffs from my Numatic Henry and and then use both the standard and 1.25" machine ends which will allow me to flip the taper. It'll be interesting but I have a feeling the standard taper will work better due to the greater resistance being encountered later than sooner.

 

[blackheart]

Findings!

Here's what I did, I removed the tool end cuff from the hose and measured the airflow in it's normal configuration I got 4252 FPM or 110.97 CFM I normally get about 108 with the cuff attached.

Then I got out my 1.25 machine end and attached the hose backwards to the machine like the Miele Design and I got 3937 FPM or 102.75 CFM

Now here's where things got interesting. I took a crushproof extension hose that I have around and cut it to about the same length as the OEM hose this hose is a consistent diameter all the way through. It actually got a higher CFM than the inversed taper measuring in at 3994 I did even see it jump to 4000 once or twice I'm rathered confused by this you'd think the inverted taper having a larger area where in theory there should be less resistance to flow would have the advantage.
I guess with it being a different make the materials or even the design of it may be smoother flowing than the OEM hose.

TLR The standard taper works better than an inverted one.
Taper: 110.97 CFM
Inverted Taper: 102.75
Standard hose: 104.24

 

[eurekaprince]

Thanks for this Blackheart. But I am not sure the test results are clear to me. Do they indeed prove that narrowing the hose diameter towards the canister improves air flow and pick-up? Or does the reverse - like a Henry hose - do better?

 

[vacuumdevil]

So nobody's familiar with the concept of velocity stacks?
Here's a link to the concept.



https://en.m.wikipedia.org/wiki/Velocity_stack

 

[blackheart]

Brian

Yes, the normal taper (wider towards the machine) worked better than the inverted taper(narrower towards the machine)

 

[eurekaprince]

Thanks for that clarification...makes sense to me. Though I studied physics in college and high school, I can’t remember all the details about centrifugal forces, etc. All I know is that when I attach a crevice tool to any vacuum hose, the sucking power increases at the tip of the attachment, even though the motor power has not been increased.

So it still mystifies me as to why Miele would design a “reverse tapered” hose for the Blizzard. I’ll have to watch the above video to see if it’s explained there...