Water expansion & pressures

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r2d2hp
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Water expansion & pressures

Post by r2d2hp »

Hi All

Anyone any experience with water expansion rates and pressures. Am trying to workout if the expansion tank is large enough following the fitting of a much larger radiator

If the fluid in the cooling system rose from zero degrees to 90 degrees (cooling system full to brim of fluid) how much fluid would it push into the expansion tank. System holds 7.5 litres of fluid and rad cap is 1,3 bar

Have been doing some experiments today where I pumped cooling system up to 19psi at about minus 3 degrees this morning and over the day it rose to 21 psi but ambient temp only made it to about 4 degrees.

So in simple terms if a can could hold 7.5 litres of fluid. and was heated from zero to 90 degrees what would the pressure be inside the can?

regards Reg



scudderfish
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Re: Water expansion & pressures

Post by scudderfish »

According to https://www.engineeringtoolbox.com/volu ... d_315.html, 7.5L would become appox 7.9L. To not blow a 1.3bar cap, you'd need an expansion bottle of 1.2L or bigger (I think)

stevieturbo
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Re: Water expansion & pressures

Post by stevieturbo »

If you feel the bottle is not large enough....just run less water in the system. It doesnt have to have a larger bottle.
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r2d2hp
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Re: Water expansion & pressures

Post by r2d2hp »

The system looks like this,

https://www.google.co.uk/search?q=s2000 ... 9601186842

The rad cap is a two way affair where it passed fluid to the tank when above 1.3 bar and draw it back as the system cools down.

I was wondering at what increase in temp does it start to pass fluid to the expansion tank. Would assume at 90 degrees the 400 ml expansion would have far passed 1.3 bar if the system was fully sealed.

The system has over flowed the expansion tank a couple of times so was wondering do we need a larger expansion tank or do we have another problem

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