A manometer with an open end filled with mercury, Fig1 shows the system at atmospheric pressure and Fig2 shows the system with a pressurized pipe, what is the maximum pressure that the pipe can have before the liquid spills out?
http://i.imgur.com/cK7cBBO.png

I don't really understand how to solve this problem, the hint is to, "Calculate the difference in height between the mercury levels in the left arm and the right arm of the manometer under pressurized conditions.

Not really sure how to do this, I think I understand the system but I dont know how to get the difference between the arms

Question

A manometer with an open end filled with mercury, Fig1 shows the system at atmospheric pressure and Fig2 shows the system with a pressurized pipe, what is the maximum pressure that the pipe can have before the liquid spills out?
http://i.imgur.com/cK7cBBO.png

I don't really understand how to solve this problem, the hint is to, "Calculate the difference in height between the mercury levels in the left arm and the right arm of the manometer under pressurized conditions.

Not really sure how to do this, I think I understand the system but I dont know how to get the difference between the arms