The boiling point of water is 100c at 1bar which is sea level atmospheric pressure. The higher the altitude the lower the boiling point, did you know you can get water to boil at 27 degrees centigrade if you can get the atmospheric pressure to below 50 millibar. I am being questioned about the truthfulness of my statement about rad boiling over at 115c and some inane comment about the puddle of water on the road side being my tears. I still stand by my statement because it is true, my temp gauge was reading 115 when I turned the ignition of within seconds water/steam was hissing out of the overflow or breather or whatever you want to call it. Someone stated that the radiator system is a pressurised system so water wont boil at normal 100c temp. Hmmmmm OK to disprove my statement the radiator system on a Ducati has to be pressurised at 1.8bar (1,800 millibar) now bear in mind the hoses are only held on with jubilee clips, there is an overflow pipe which is not an electronically controlled valve so how they can maintain a constant pressurised system to that extent I haven't got a clue and I doubt they can without some intricate electronically controlled valves to alleviate pressure before it blows the hoses off. A tried and tested experiment, a piece of pipe approx 180mm internal diameter loaded with a steel ball of slightly less diameter, when 1.5 bar of pressure is added to the equation the steel ball is shot out at such a velocity that it pierced a 6" piece of solid oak that was placed 20 feet away.
The fluid in your radiator isn't water, it is water with stuff dissolved in it, and that stuff will also raise it's boiling point.
The tube and steel ball was put under pressure 1.5 bar, the point was made to show what 1.5 bar of pressure can do, I dont think the materials that go to make up my radiator and hoses will stand up to that, which suggests that it cannot be pressurised to a point to elevate the boiling point of water. Yes it has additives but are they enough to increase the boiling point of water way past 115 c ? wheres the evidence ? You are offering an argument without any evidence to substantiate what you are saying.
Two issues. Water, with additives, under pressure could easily elevate the boiling point over 115C, I have seen 120C on my MTS display. What the radiator and hoses are made of is another question entirely. Pressure is a force per unit area. Energy is the ability to do work. Stating the pressure of a system without other information tells you nothing about the energy level of that system. There is no direct correlation between pressure and energy.
when you stop the motor the water pump stops so you get latent heat build up at the hottest parts causing it to boil over. Mine did it in Italy, parked up boiled over. 115-120 degrees. Regularly in town on warm days I see 108/110 on my 05 999.
So wheres the evidence then? type of coolant additive used and its boiling point, if added to water how many parts of coolant per parts of water, what is the effect on the boiling point and then you also have to take in to consideration of how pressurised is the radiator system. Even if we are using the exact same coolant it will depend on mixture (parts additive to parts water) as to what temp they will boil at far to many variables to actually disprove or prove the argument.
Of course there are many variables, which is why manufacturers, Ducati included, will specify which products to use and at what concentrations.
Then you are reliant on using an exact measuring tool to ensure mixture is always consistant, the usual is the measuring jug in the kitchen but that is not 100% accurate so even then there will still be a discrepancy and boiling points will be different.
How accurate does it need to be, I don't suppose it has to be exact. Is there a pressure relief valve ? If there is, and I suspect there will be one somewhere, that is the most likely cause of a system boiling over. Also as the system vents the drop in pressure to atmospheric would result in instant steam from any fluid vented.
If you want the same boiling point every time so you know exactly when SOL is reached then yes it has to be exact. Not sure about pressure relief valve but if there is one and it is like any other Ducati part then it will operate as and when it feels like.
a tube 6" long x 6" diameter pressurised to 1.5bar A tube 20ft long by 6" diameter pressurised to 1.5 bar its still 1.5 bar of pressure irrespective of length or diameter. And I think you missed the point of steel ball in tube. Putting something under that much pressure will cause damage if it is not purposefully built to withstand that pressure. Someone offered the statement that the rad system is pressurised so shouldnt it boil over at a much higher temp. To get water to boil at a temperature in excess of 115 c requires a minimum pressure of 1.7 bar or 1700 millibar.
That's because it is. Please study the subject (Google is your friend) before adding a "disagree" on my post. Especially since you're trying to prove something that's against the laws of physics.
May I suggest you do the same to or be more precise in your answer. Water boils at 100c at normal atmospheric pressure. If water is in a pressurized system it will still boil at 100 c. No one has actually clarified to what pressure the system is pressurized so I made the assumption it is 15 psi or 1 bar or 1000 millibar which is the same as normal atmospheric pressure.
No, it does not. In a pressurized system the boiling point will be higher. What Is the Boiling Point of Water? Pressure Cap - How Car Cooling Systems Work 15psi = 1034mbar.
Oh look a link to Google to prove what your saying is right. You have read that a radiator cap increases the boiling point of your coolant by 25 c and thought excellent this proves that twat CS wrong. No it doesn't prove me wrong. Back to basics. The radiator cap increases the temperature at which point the rad will boil over not the physical boiling point of water. Atmospheric pressure has an effect on the boiling temp of water. The higher you go the lower the boiling point. The water in a radiator minus any additives reaches boiling point at 100 C, but because of the cap and the built in spring stops it from actually boiling over because it requires 15psi to operate the cap. In a rad there is normally air between top of water level and bottom of cap, water reaches boiling point at 100 c at which point creates steam which fills the void between the top of the coolant level and bottom of the cap therefore creating pressure, once this pressure reaches 15 psi on a std cap it pushes against the spring mechanism to allow water to go through the overflow simulating boiling over, by this time the water temperature is in excess of 100 C. Hence why the statement in Google says that the cap increases the boiling temp by 25c The radiator only becomes a pressurised system once the water starts boiling. A true pressurised system is where fluid, air or gas is forced in to a confined space beyond its normal capabilities therefore compressing it to fit more in than would normally be possible.
