# Determine equivalent vacuum for water depth

• Jerry Prothro
In summary, the conversation is about determining the maximum water depth that a motor can operate without water ingress. The plan is to use a vacuum pump to create differential pressure and correlate it to water depth. The issue is finding a formula for determining the equivalent water pressure based on the vacuum that can be held. It is mentioned that the maximum vacuum of the pump is 25 inches of Hg and the density of mercury is 13.5 times that of water.
Jerry Prothro
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

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.

## 1. What is the "equivalent vacuum" for water depth?

The equivalent vacuum for water depth is the amount of pressure that would need to be applied to a column of water to achieve the same depth as the water itself. It is often measured in units of length, such as meters or feet.

## 2. How is the equivalent vacuum for water depth calculated?

The equivalent vacuum for water depth is calculated using the formula: pressure = density of water x gravitational constant x height of water column. This takes into account the weight of the water and the force of gravity acting on it.

## 3. Why is it important to determine the equivalent vacuum for water depth?

Determining the equivalent vacuum for water depth is important for various scientific and engineering applications. It can be used to measure the pressure at different depths in bodies of water, to calculate the buoyancy of objects, and to design and test equipment for underwater environments.

## 4. How does the equivalent vacuum for water depth change with depth?

The equivalent vacuum for water depth increases as the depth of the water increases. This is because the weight of the water above exerts more pressure on the water below, resulting in a greater equivalent vacuum.

## 5. Are there other factors that can affect the equivalent vacuum for water depth?

Yes, the temperature and salinity of the water can also affect the equivalent vacuum for water depth. Warmer water is less dense and therefore requires less pressure to achieve the same depth, while saltwater is denser than freshwater and would require more pressure.

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