Patient Lift System Load Requirements

[CBSE]

I've designed hoist systems and crane systems in the past, but haven't done anything specifically relating to lifting patients. Are there any special load amplification requirements I should be aware of? Maximum lifting weight of the system is 450 lbs. I'm assuming I just need to design it for 25% impact loading which is typical of a powered monorail crane.

Thanks,

 

[thaidavid40]

Interesting design task! It sounds like you are looking at the ASCE 7 requirements for lifted loads, including impact. I believe you should also probably be looking at the ASME requirements for lifting devices associated with people, and people movers. The requirements there will be significantly different (AND HIGHER) than the ASCE requirements, which are typically meant for building structures.
Good luck - Dave

Thaidavid

 

[jayrod12]

I've done a bunch of these, we design for 900 lbs (load factor of 2). rarely does this cause too many problems, even in existing roofs.

 

[CBSE]

Great! Thanks for the info. I will look into the ASME and the 900 lb requirement. What about deflections? I'm assuming I would want to keep it minimal to prevent any "bouncy" kind of feeling?

 

[jayrod12]

Generally I've only spanned the rails from joist to joist so 6 feet max so deflection never governs.

 

[CBSE]

I have to span about 15ft in my max span. I can keep deflections down around .3 inches with a 4x, it should be minimally noticed, but it's something that could end up being a pain in the neck if it actually feels bounce to the patient or the providers.

 

[XR250]

I think a 450 lb patient will have enough built-in bounce that the beam deflection will get lost in the noise :>

 

[racookpe1978]

Unfortunately, I'd say 450 lbs er patient is a bit low - there are many bodies out there grossing above 600 lbs, and a few at 800+.

Roof loads? So you'd plan on suspending the live medically-armed load (lawsuit!) from the rafters/beams of the ceiling? Seems like that would be the weakest (unknown quality) link.


Could you use a gantry-type rolling crane with rollers on both sides of the bed? Or does it need to be permanently in place above the bed?

 

[jayrod12]

These are extremely common and almost always hung from the roof structure. Some of the ones I've seen in new builds are hung with threaded rod and uni-strut from OWSJ and perform fine.

 

[DamsInc]

I was a summer student for a consultant that designed anchors for these systems. Don't have any details design-wise, however they would always require load testing after installation.

 

[XR250]

I saw a show recently about a man who was in excess of 1000lbs. Might want to design for that load.

 

[CBSE]

There is a drop ceiling about 18" below the bottom of the roof joists. The beams I'm designing would support the rail for the lift. The lift's go from the bed into the bathroom and have a 90deg turn for entry into the bathroom. I don't have any way of supporting them off of the roof so I'm left with wood beams. I don't necessarily see the "lawsuit" factoring in if it is designed and detailed appropriately.

Hadn't contemplated a 1,000 lb person!!! These will be elderly folks. The system actually says it's max working weight is 625lbs for testing purposes. It's "rated" load rate is 450 lb. I'm designing to the 625 lbs with a factor of safety of 2.