hey guys an engineer would love some help to get an explanation, Thank you.

[mahony]

Problem:

Drilling in London and high pressure Nitrogen gas pockets are hit killing two workers due to lack of ventilation.

 

 

 

Background and proposed theory:

• Underneath London in the 1940s the water table was lowered underneath an impermeable layer of clay.
• This created a vacuum in certain areas
• Due to the vacuum the water cavitated
• Air came out of the water and formed above the water and below the clay.
• Iron present in the clay oxidised causing the removal of Oxygen in this air and resulted in Nitrogen rich air
• Water table increased (due to less demand officially) and resulted in the Nitrogen under high pressure.

Question:

Does this theory make sense to scientists?

 

Thanks for your help regardless I really appreciate it

 

Mahony

[doG]

Question:

Does this theory make sense to scientists?

Sure. Iron does the same thing in double hulled ships. The space between the hulls gets depleted of oxygen as the surface of the steel turns to iron oxide. Entering that space for maintenance without ventilating it first will suffocate you.

[mahony]

Sure. Iron does the same thing in double hulled ships. The space between the hulls gets depleted of oxygen as the surface of the steel turns to iron oxide. Entering that space for maintenance without ventilating it first will suffocate you.

 

Really interesting reply thank you

[J.C.MacSwell]

Sure. Iron does the same thing in double hulled ships. The space between the hulls gets depleted of oxygen as the surface of the steel turns to iron oxide. Entering that space for maintenance without ventilating it first will suffocate you.

 

Sadly, it is not uncommon. You have to check the air (as well as have other safety procedures in place) before any tank or confined space and rusting certain depletes the oxygen.

Edited July 22, 2011 by J.C.MacSwell

[mahony]

Cheers I am going to try and read up with regards it occurring in those situations, I'm afraid I was unaware of them so thank you very much.

 

Currently I have set up an experiment and I have lowered the pressure in a soil profile completely saturated with water. The soil profile is resting on a mesh. Below the sample is a reservoir of water and above there is a reservoir of water. I have gone to -80kPa. I lowered the pressure by pumping water out of the sample reservoir below. Cavitation is occurring and there appears to be an air pocket forming on the top. I was wondering though what would you expect to happen to the pressure as cavitation occurs. In two tests I ran so far I have got conflicting responses. In the first the pressure lowered and in the second it stayed the same. When air comes out of the water and fills the vacuum what will happen the overall pressure?