Pump for a quench tank

Phil Dwyer said:
Thanks for sharing your R&D with us Dixieblade57. (Sorry, my participation on BF is such that I've missed your name.) These open explorations are helpful to many of us.

I always wonder about how hot water heater elements work. Do they heat by just being fully on (high heat temp) and stay fully on until the liquid reaches the target temp when they are shut off via the thermostat? If so, wouldn't that accelerate oil degradation? I believe I've read quenchent specs that refer to heating temp specifications cautioning using too high a heat. Maybe it's a mute point because hot water heating element heat with low temps? I wonder what folks thoughts are on this. Thanks, Phil
Click to expand...

Phil, I am not the smartest fellar out their but will try and address what you are talking about. My idea for the element is that it preheats to the needed temp for quenching. In this case I think I will run a thermostat on the heating element, otherwise yes as long as their is power there it continues to heat, (by being fully on), and I would have to be cautious and not let the heat build to much while using the element in the quench tank. A replacement thermostat can be bought at the hardware, for around $11.00, so that is a small investment.

I will also install a thermometer to monitor the overall temp of the oil, as each quench will cause the heat to build in the oil. I may invest in one that will alarm when the temp gets over a certain degree. My son in law is a electronic and computer wiz kid so he can help out there. At present time I am not building enough knives that I feel I will have to install a cooler but I plan on making a provision for one so if at a later date I feel the need it will be only a matter of adding it into the system.
Because I believe you are correct in stating that overheating is one of the causes of degradation of the oil no matter what kind it is.
 
To control the oil temp, merely use a TC ( like the one linked),a cheap low temp PID, and an SSR, with the heating element as the load. Set it at 130F and turn the switch to ON. Its that simple.
 
Pardon me if I'm speaking out of place, but I found the following article earlier while researching 1095 quenching techniques and alternatives:
http://www.quenchtek.com/pdf_files/technical_paper/Proper%20Agitation%20Dictates%20Quench%20Success%20PI.pdf
While I'm by no means advocating impeller agitation over forced jet, I thought the article might be of some interest in the conversation over questions of agitation and direction. For example, the piece includes phase-cooling, volume/mix, and draft/flow charts that compliment earlier comments and might help alleviate some of Dixie's headache.
Sorry if the article's been posted before--I tried searching beforehand to check but it wasn't turning up.
 
Friends: The reason I ask is not because of concern of over heating the entire volume of oil. I understand a TC and PID can be set to control that, say like at ceiling of 130F like Stacey's example. But, if the element is "wide-open red-hot" until it gets shut down by the controller, than wouldn't the oil in its immediate vicinity (which will be all of the oil over time and multiple exposures) be at risk for accelerated degradation? Sort of like, but not as drastic, as plunging super heated steel in to heat up the oil? Perhaps robustly circulating the oil would minimize any localized overheating effects, if there are any. On-the-other-hand if like Ron_m80 points out, there may be elements that have low operating temperature ranges, seems like that would be preferable.

Dixie: I hope you keep us posted on your progress. Thanks!

Ed: That circulation article is a good read. I especially enjoyed the circulation patterns. Notice how the smallest volume is 50 gallons...all the way up to >3000? I guessing most folks around here probably are using volumes in the 5-10, maybe up to 20, gallon range. Not sure if that make a difference re pump verses impeller though.

BTW here's Proper Agitation Dictates Quench Success Part II.
 
I finally recalled the name of that other little pump maker. most of the prices I see online are exaggerated, these are not so expensive.

EDIT: to add the name Grundfos

Still wondering what the end goal of the fluid pumping is.

Phil, immersion heaters will more than likely be fine for this. Though you might want to stay away from anything rated as "instantaneous" :D

That article looks cool thank you.
 
Convection - a form of heat transfer

I am going to attempt to answer all of the questions posed!
Phil when the element is turned on it reaches it maximum temp slowly, (it has to build to that temp) and it will remain at that maximum temp unless controlled by a thermostat which will cause it to cycle on and off at what ever temp the thermostat has been set to.

When you plunge a hot rod into the quench to bring it too temp you are depending on convection to act a form of heat transfer. This takes time and there is not guarantee as too if all parts of the oil have achieved the proper temp needed for the quench to be effective.

With a pump the pump can be turned on prior to the element, thus ensuring a more uniform heat to the oil. If the pump is constantly circulating the oil you are still depending on convection to heat the oil but you will get a more even heat to that oil!

Agitation is the second key to get a proper quench. We all do agitation when we move the blade back and forth during the quench. If the oil is being pumped from the bottom up as Stacy pointed out and as my crude drawing shows the oil will rise toward the top, and it will be pushed out as the drawing indicates and as Stacy stated it will fall back toward the bottom in an umbrella fashion. In short the pump gives a more equal heat and a better agitation to the quench oil. All of which should be aid in getting a proper quench as well as prolonging the life of the oil.

At this time I have not read the article as I had a dog who has a ruptured disk in its back at the vets this morning, but will read it when I finish typing this.

I plan on doing a WIP on the build when I finally get everything together for it and I will try to do a video showing the final result when I get thru!
 
OK I have read the article. And after reading it I plan to sticking to the pump and to the tube coming up from the bottom as Stacy suggested as the out put. The article will not let me copy it so refer to the part entitled Draft-Tube Mixer Design, page 16. I also agree with Phil in that I feel this is a reference to commercial type quench tanks. considering the small volume of quench oil I will be using in my tank I feel that the pump and the bottom output will work the best.

Also I am going to go with what I know. I did construction for 35 years before I got hurt in a five car pile-up and had to have back surgery. I once worked for a fellow that had a impeller mixer just like the one they recommend as best (in figure 3B page 14).

We used this agitator chucked up is a old metal case 1/2" drill. If you know anything about the old drills I am talking about, you know they were work horses. Any way to make a long story short the agitator was great to mix up hard to mix stuff. However the only way you would get to mix all the way thru is to constantly pulling it from bottom to top. It was mostly used in 5 gal. pail application and with the bottom to top movement it took for ever to make it mix and it would not mix consistently all the way thru!
 
Last edited:
I have it now. forced convection / agitation, and uniform temp.

I am trying to picture this thing in motion. You have posed to "discharge from the bottom going up in a jet, while you siphon quenchant from the upper region of the oil. to pump up from the bottom again."

I disagree with this movement of heat vs. fluid, as it is attempting to counteract convection. The hot oil will move to the top, and the cooler oil will migrate down toward the bottom. If you want to agitate the fluid well for the sake of the small boundry between the oil and the surface of the metal being quenched you have to work with convection so that the motive force is aided rather than fighting with natural convection. Just my opinion.

Going off of the stuff from the articles (I liked reading them by the way, and will read them again when I get off work :D). I would probably build my motive force or pump if you will from parts and metal, rather than buy one, but thats me.
 
ron_m80 said:
I have it now. forced convection / agitation, and uniform temp.

I am trying to picture this thing in motion. You have posed to "discharge from the bottom going up in a jet, while you siphon quenchant from the upper region of the oil. to pump up from the bottom again."

I disagree with this movement of heat vs. fluid, as it is attempting to counteract convection. The hot oil will move to the top, and the cooler oil will migrate down toward the bottom. If you want to agitate the fluid well for the sake of the small boundry between the oil and the surface of the metal being quenched you have to work with convection so that the motive force is aided rather than fighting with natural convection. Just my opinion.

Going off of the stuff from the articles (I liked reading them by the way, and will read them again when I get off work :D). I would probably build my motive force or pump if you will from parts and metal, rather than buy one, but thats me.
Click to expand...

I am not trying counteract convection, in fact quite the opposite, I am trying to aid convection by circulating the oil and help agitation in the process. However my intent was never to convince anyone that my way was the right way and we are all entitled to our opinions. I was merely listening to the discussion and after listening I decided that what I had been told more or less convinced me that the information I had received was correct.
The article that Ed posted and personal experience, also convinced me that the theory works. However like I said I am not trying to convince anyone. You are left to draw your own conclusions!
 
HummI'm definitely here for this discussion. Not to impose my thoughts or dirrection. I understand fluid movement and heat transfer well enough, i come to the makers forums to fill in some blanks.
 
Let me see if I can illuminate the discussion.

There are two types of convection going on in the tank -
A) The first one is the thermal convection of the oil from the heating element, which is upward, and back down the tank sides. A far as the quench goes, this does not factor in. It only affects the heating rate and evenness of the tank temperature. In the case of quenching a 1500F blade into 130F oil, this is insignificant.
B) The other is the convection along the blade surface from the vapor jacket, and this is mainly just upward ( in the few seconds that are critical).This is where we make or break ( sometimes literally) the HT of the blade. This is timed in hundredths of a second, and the rate of transfer of the heat from the 1500F blade to the 130F oil is critical.
The pump creates a fluid flow ( much more powerful than convection) in the same direction as both these convections, thus keeping the tank temperature more even, and speeding the quench rate.

It does this by doing two things:
1) It brings cooler oil past the blade, removing the superheated oil and collapsing the vapor jacket sooner.
2) It creates an environment where localized areas of hotter/cooler oil and larger/smaller vapor jackets will be harder to maintain. This greatly enhances the evenness of the cooling, and prevents warp and twist from one side cooling faster than the other.

I used to use large impeller tanks up to 10,000 gallons when I was a chemist. Impeller rate, size, flow direction, etc. were often critical to a reaction happening right or wrong, and had to be calculated into the process. The tanks and impellers in the linked article are for commercial quench tanks of 10 to 100 times the volume of most all knife quench tanks. They will be required to evenly and quickly cool huge amounts of steel, and repeat the process often. The differences in use are huge, but the principles are similar to our needs. A small flow rate to insure upward flow and even quenching are all we need.Turning the tank volume over about 5-10 times a minute will be more than enough to meet our needs. For the average 10 gallon quench tank ,that requires a 50-100GPM pump.
 
You must log in or register to reply here.
Back
Top