Determine equivalent vacuum for water depth

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To determine the maximum water depth a motor can operate without water ingress, the relationship between vacuum pressure and water depth must be established. The maximum vacuum of 25 inches of Hg translates to an equivalent water pressure of 28 feet of water, considering mercury's density. The formula rho g h, where rho represents the fluid density, g is gravitational acceleration, and h is the height of the fluid column, is essential for this calculation. Understanding this correlation will help in assessing the motor's operational limits under varying water depths. Accurate calculations are crucial for ensuring the motor's reliability in submerged conditions.
Jerry Prothro
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Hello, I need to figure out the max water depth a motor will operate without water ingress. The plan is to use a vacuum pump to create differential pressure and correlate that to water depth. My issue is the correlation between the vacuum and pressure. Can someone please provide a formula for determining the equivalent water pressure which the motor can withstand based on the vacuum I can hold? The Max. Vacuum, of the pump is 25 Inches of Hg.

Thanks
 
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I'm pretty sure rho g h will be in there somewhere.
 
Mercury is 13.5 times denser than water , so 25 inHG = 337.7 inH2O = 28 ft of water.
 

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