Equipment pad/foundation question? 1

[gte447f]

I am checking the concrete pad design for a piece of equipment (i.e. small commercial chiller w/ 70 ton cooling capacity). The chiller is 8'x8'x8' and weighs 5,000 lbs. Are there any special concerns, since this is a piece of "equipment"? For example, vibrations, impact loads on the pad, heavy maintenance loads on the pad, etc. If not, shouldn't a standard 5 or 6 inch slab on grade be sufficient, since it isn't much heavier than an SUV on a driveway?

 

[DWHA]

Ask the manufacturer for info on viberation, impact, maintenance, etc.

Other than frost heave (location dependent) I do not see much of an issue.

 

[Ron]

Assuming that frost heave is not an issue, then drainage is the next issue. Make sure your slab is on a well compacted, but free draining subgrade. Your slab thickness estimates are fine. You might want to use a thickened edge slab for confinement and to reduce the potential for erosion.

 

[delagina]

some equipments specially vibrating requires a minimum of 5x or 3x weight of equipment for the the foundation.

 

[Lutfi]

I design equipment pads like this all the time for our MEP’s in our office. Vibrations should not be a problem these days. Almost all chillers start softly and most are controlled by Variable frequency Drives (VFD). We have developed two pad options that we leave let the contractor to choose from. One is an isolated pad that will have joints all around the chiller plant slab. The second is a pad that can be added on top of the slab after it is placed. Here are some pointers to keep in mind:

1. Coordinate the chiller foot print with MEs. They often change their minds and selections.
2. Provide a pad that is a minimum of 6” all around the chiller.
3. I like to have the pad at least 6 inches above finish floor. Water can be present in chiller plans and that will prevent the water from reaching the “feet” of the chiller.
4. Coordinate the location of the pad/chiller in relation to other chillers. NEC requires certain clearance in front of electric and control panels.
5. Chamfer the perimeter of the equipment pad.
6. If you want to use the pad on top of newly placed slab or an existing slab, require the surface of the slab be roughened and use bonding agent.
7. I suggest the use of 4000 psi concrete.
8. Show the neoprene type pads that the chiller manufactures requires under the “feet” of the chiller.
9. Size reinforcement as required by design.

I hope this helps.


Regards,
Lutfi