vibration structure support fan

[shinobi9]

Good morning.
I work on designing hvac plants but in this case I need a hand on a side theme or I have to design a small support structure for a fan exchanger of 6000 mc/h. this structure stands on 4 legs of support and is stuck to the wall in a frontal point as you see in the figure. the goal is to isolate the vibrations to the maximum. .now I don't have fan rotation data (I imagine that the problem is the multiple frequencies of the fan rotation frequency)..but reasoning in general what do you recommend me to do? I thought I could isolate the legs with antivibrating feet and in some way isolate the wall. Thank you.

 

[MassiVonWeizen]

the antivibrating feet and a possible system of compensation between structure and wall limits the noise of vibrations, but not the stress at the expense of the structure; therefore better to insert antivibrants between fan and structure so that they partially absorb stresses.
However I would start by improving the structure that looks very slim.
because vibrations will be mostly lateral, due to rotation, add reinforcements in that direction.
add a fastening up to the wall vertically

 

[Onda]

it is advisable to make the structure as rigid as possible and support the ground, without insulation and then mount over the heat exchanger on insulation. because if you put the insulators on the 4 legs and on the wall fixings you risk not getting them to work well. instead you make your structure rigid and then put elastic feet for your mass located above.
then you have to check that the pins are suitable for cutting the frequency of the fan.
Remember to put, if possible, an elastic element on the pipes. otherwise vibrations and loads pass through these.

 

[meccanicamg]

the fan turning eccentric, due to the disposition of the center of rotation not exactly on the center of rotation will graft a vibration and therefore a stress especially on the ground.
then the fan, in all its directions must be shocked. the surrounding metal structure must be rigid and should not undergo vibration.
you can contact the company ace and with them determine the correct antivibrants/smorzatori appropriate for your application.

 

[ian3d]

to be more effective and work better in stiffening the structure, the tirants, which rightly are expected, should get to the ground

 

[shinobi9]

thank you all for the answers! Consider that it is a heat exchanger with internal fan and the total weight is about 100 kg.
I had already evaluated to make the thickest structure (I wanted to use tubular steel 8x8 cm) and in addition to the countervents of the reinforced beams on both directions. planned also to isolate the channels by inserting a section of channel with flexible joint.
the thing I thought (not visible to drawing) is to isolate in practice at these points:
-Antivibrant feet on the legs (with the same ones resting on an antivibrating carpet, to be evaluated. . )
- antivibrating between structure and machine
- antivibrants between wall and structure
as the fundamental vibration frequency will be given by the unbalance of the fans (they are 2) and acts in all directions I wanted to make so that the antivibrants between wall and structure acted in a sense (both in the sheet for example) and those on the legs in the perpendicular sense.
I don't understand if you're basically telling me that it's only enough to isolate between fan and structure and then the rest all stiff!? .. if isolo between fan and structure that between structure and wall/solar is not better?

 

[MassiVonWeizen]

I don't understand if you're basically telling me that it's only enough to isolate between fan and structure and then the rest all stiff!? .. if isolo between fan and structure that between structure and wall/solar is not better?

We're all telling you that the structure must be rigid.

it is better to make the structure as rigid as possible

the surrounding metal structure must be rigid and should not undergo vibration.

to be more effective and work better in stiffening the structure,

the antivibrating feet and a possible system of compensation between structure and wall limits the noise of vibrations, but not the stresses to load of the structure;

if between structure and wall you put an object that is not rigid, insulating or shock absorber that is, how do you maintain rigidity?
the shocker under the fan you have to put them because you can't prevent it from vibrating. by removing them part of the vibrations to the structure that will be minor as best is the shock absorber.
If you put shock absorbers between the structure and part of the vibrations received by the fan may be partially damped, but do not remove and risk that you go to resonance (on this point I ask the most experts to correct me possibly).

 

[shinobi9]

ok so I have to isolate only between fan and structure and make the rigid structure. But I still don't understand the physical reason why if he isolo in both points is worse. the repost "pass the vibrations" ok... but it doesn't tell me anything I would like to understand the question from analytical point of view.

 

[Cadinpiedi]

ok so I have to isolate only between fan and structure and make the rigid structure. But I still don't understand the physical reason why if he isolo in both points is worse. the repost "pass the vibrations" ok... but it doesn't tell me anything I would like to understand the question from analytical point of view.

Excuse me if I interfere,
it would be worse because the fan would also drag the structure into vibration.
to understand imagine that the antivibrants you would like to put under the fan and under the structure are made of jelly, they would sussulte both the fan and the structure, and the sine wave of oscillation of the two masses would overlap with unpredictable results, while instead if the structure is well planted on the ground you will have to calibrate only the antivibrants under the fan, obviously with the advice of an expert on the subject.

 

[shinobi9]

All right, thank you. !