Model Lungs

I am trying to sort my model lungs in a bell jar out.
The original 'lungs' had popped and made a sticky gooey mess all over the inside of the bell jar and on the diaphragm.
I've managed to clean them all up and have replaced the lungs with bog standard party balloons, but can only get 1 of them to inflate!!
I have tried changing one then both of the balloons, made sure the pipes are not blocked but it makes no difference.

Any help would be really appreciated.
Thanks
 
I am trying to sort my model lungs in a bell jar out.
The original 'lungs' had popped and made a sticky gooey mess all over the inside of the bell jar and on the diaphragm.
I've managed to clean them all up and have replaced the lungs with bog standard party balloons, but can only get 1 of them to inflate!!
I have tried changing one then both of the balloons, made sure the pipes are not blocked but it makes no difference.

Any help would be really appreciated.
Thanks
Try inflating the balloons before you attach them, this should sort it out
 

Peter Sigsworth

COMMITTEE
Try inflating the balloons before you attach them, this should sort it out
I agree with this - if one has a unstretched skin and the other an old stretched one then the stretched one will inflate and the other not. So blow them both up fully to stretch the rubber equally and let them down before you attach them to the tubes.
 
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Hairline cracks in the pipe / pinprick hole in the balloon?
The balloon is fine, I've used so many, so it must be the pipe but I can't see anything.
I've given up now... it works enough to get the point across.
It's just that only 1 balloon fully inflates, the other inflates to the minimum point before it stretches.
The balloons have all been pre-blown!
I am officially stumped.

Thank you all for your suggestions :)
 
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