Parks 50 Quench question

David Stifle

David Stifle

Joined
Nov 20, 2008
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How long do you need to quench in Parks 50 to get a completely hardened blade? Four seconds? Six? I'm new to this oil and a little concerned the oil will flash on me as 270 degrees isn't much. Seems a red hot blade would get it up there real quick. I would greatly appreciate some input on using this oil.
 
I have never really had problems with Parks flashing in the tank. The times I have had that happen was with slower oil like AAA or Tough Quench heated up to say 150 when I was trying to edge quench. I use #50 at room temp unless it is below 70 in my shop which doesn't happen much here in Florida. Even then, i only heat it up to 80-90 then. I usually give it about 7 seconds or so if the blade has no clay and a few more seconds if it does.
 
It will only flash if the hot blade is pulled out too soon. If the blade is kept under the oil surface until it cools, there will be no flames. This applies to most all quench oils.
 
Stacy, I accept what you say, but I don't understand the mechanics behind it. It seems to defy common sense. If I put a 25" blade heated to 1400 degrees or more into the quench it will surely heat the oil well past it's flashpoint, so why doesn't it flash, regardless of wheather the blade is submerged or not? I feel I'm missing something elmentary here, but can't get it.
 
If the blade is submerged there is no oxygen to allow combustion.Also though you are heating the oil past flash point the volume of oil is also cooling the oil at the same time.
Stan
 
David Stifle said:
Stacy, I accept what you say, but I don't understand the mechanics behind it. It seems to defy common sense. If I put a 25" blade heated to 1400 degrees or more into the quench it will surely heat the oil well past it's flashpoint, so why doesn't it flash, regardless of wheather the blade is submerged or not? I feel I'm missing something elmentary here, but can't get it.
Click to expand...



You can put out a match in a bucket of gasoline, as long as you dunk it fast enough that the vapour won't light.
The oil is nowhere as volatile as the gasoline.




It will only heat that very small amount of oil close to the steel to the flash-point.

Since it is submerged, no air means no flash- no burning and the rest of the oil will carry that heat away

The volume of the oil, means that even though it is red hot, the whole 5 gallon, volume of oil only gets slightly warmer.



If you quenching that red-hot steel in say, 1/2 an ounce of oil, it may flash because the quantity of oil is insuffficent to cool the steel
and it will be exposed to air.



EDIT-stan beat me to it.
 
Good point about vapor. I don't really see there being enough coming off of #50 at room temp to ignite. Heat it up and that is another story. The flaming blade when you do an "interrupted" quench is always fun.
 
Just like edge quenching and interrupted quenching, tongs that are too hot can set it off too. That one's easy too avoid though.
 
When I did electronics, I was at a place that had very high current high frequency equipment ( BIG radar). The contacts for some of the relays were in jars of oil. That way the arc that formed when the contacts closed did not burn the contacts. The sparks in the oil looked impressive. A visiting highly paid Government official asked why the oil didn't explode. The tech answered that he could fill the jars with gasoline and all would be well, as long as the contacts stayed under the liquid. The questioner looked at him like he was crazy and said, "That's dumb." The tech took a coffee cup and filled it with a solvent, lit a broom straw, and dunked it in the cup ( no fire) - and said, "No, that's physics,... this was dumb.".

The physics of this is that a flame can only exist in a gas.....solids and liquids do not burn. We use solids and liquids as fuel because they are easier to store than gas, but they have to be converted to a gas to burn.
There are several related terms that are often misused.
The vapor pressure is a measurement of how easily the liquid becomes a gas at room temperature. The vapor pressure of a flammable liquid determines how easily it burns. If the pressure is low, the liquid is considered volatile. If the liquid will burn in air, and has a low vapor pressure, it is called highly flammable.

The flash point is the temperature that the gas will ignite in air with an ignition source. In quenching, there may be lots of vapor and gas, but the ignition source ( hot blade) is under the surface, so the vapors above the tank don't ignite. This is why I say to not put your quench tank right below or next to the forge. The vapors can drift over to the forge flame and ignite. This isn't really a big fire risk, but can scare the heck out of you. The difference between gasoline and kerosene in flammability is the flash point. Gasoline has a -45F flash point and kerosene has 100F. They both burn equally well, otherwise.

The final term is the flame point. This is also called burn point and auto-ignition point. This is the temperature that the liquid will self ignite in air. This is why we don't recommend heating oil to 450F and using it for tempering, as this is getting close to the flame point, and above the flash point. When it ignites, it will self feed the flames.
 
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