The data has been collected. I ran parallel events with two similarly-sized pressure pots. On the left is a Kuhn Rikon 3.5 liter pan, and on the right is a Vinod 3.0 liter. Although they each claim a different capacity, the 2/3rds mark (the maximum capacity on any pressure cooker) comes to about the same amount: 8 cups in the case of the Kuhn Rikon, and 8.5 cups for the Vinod.
I filled both pots with 8 cups of water, placed them on large burners, turned both burners on high, and started a stopwatch. I then observed and recorded events. The only real reason that I ran both pots in parallel is that the Vinod does not provide a way to tell when it has come up to pressure. While the Kuhn Rikon has a second red line that becomes visible when it has reached 15 PSI, there is no clear indicator on the Vinod. I was hoping that both pots would come up to pressure at about the same time so that I could estimate how much time elapsed between achieving 15PSI and the first whistle.
Each pan has different instructions for what to do when pressure is achieved. The Kuhn Rikon is to have the heat reduced to "low", while the Vinod is to have the heat reduced to "medium". For the purposes of this run, I took that to be the midpoint of the dial on my stove, which is marked "5". Having no way to tell when pressure was achieved, I did this when the first whistle started.
I'm told that few people cook anything longer than 4 whistles. Despite this, I collected data for 10 whistles just to get a feel for how regular the intervals between whistles is. A whistle is really a loud hiss. It sounds like "PSSSSSHHHHHT!". Each one starts suddenly, goes on for about 12 seconds, and abruptly stops.
- 00:00 start
- 06:23 I could hear the Kuhn Rikon making some noises
- 08:22 The seal on the Kuhn Rikon sets, and the indicator moves a bit. It becomes mostly quiet.
- 09:08 The 8 PSI line makes its first appearance on the Kuhn Rikon.
- 09:19 The 8 PSI line is fully visible.
- 09:48 The 15 PSI line makes its first appearance.
- 09:57 The 15 PSI line is fully visible.
- 10:05 I turn the heat on the Kuhn Rikon down to low, or "1".
- 11:10 The Vinod begins to whine like a mosquito. I turn the Kuhn Rikon completely off.
- 13:14 Water droplets appear at the base of the vent tube on the Vinod.
- 13:59 Steam is visibly comming out of the vent tube, out from under the pressure regulator.
- 17:56 Whistle #1 begins. I turn the Vinod down to medium.
- 18:08 Whistle #1 ends.
- 19:22 Whistle #2 begins.
- 19:34 Whistle #2 ends.
- 21:27 Whistle #3 begins.
- 21:39 Whistle #3 ends.
- 23:04 The 15 PSI line on the Kuhn Rikon starts to disappear.
- 23:46 Whistle #4 begins.
- 23:59 Whistle #4 ends.
- 24:35 The 15 PSI line on the Kuhn Rikon is completely gone. At 8PSI now.
- 26:11 Whistle #5 begins.
- 26:24 Whistle #5 ends.
- 28:37 Whistle #6 begins.
- 28:49 Whistle #6 ends.
- 29:?? Whistle #7 begins. Distracted by a curious child.
- 31:04 Whistle #7 ends.
- 33:14 Whistle #8 begins.
- 33:30 Whistle #8 ends.
- 35:36 Whistle #9 begins.
- 35:47 Whistle #9 ends.
- 37:55 Whistle #10 begins.
- 38:06 Whistle #10 ends.
- 38:26 Turn the Vinod off. End data collection.
Making a model presents some difficulties. The worst being that there was no clear indication of when the Vinod came up to pressure. The documentation does claim that the pot can "maintain" a pressure of 15 PSI. However, we know from the nature of the whistle that the pressure is actually oscillating, with peaks being the whistle events. For the purposes of my model, I am assuming that the pot came up to pressure about 1.5 minutes prior to the first whistle. I chose this baseline because it was approximately the interval between the first and second whistles. I'm also assuming that the oscillating has no appreciable impact on cooking time.
Based on the averages, it appears that there is an interval of about 2 minutes and 20 seconds between whistles, with the first couple of intervals actually being a bit shorter than that. Nevertheless, 2.3 minutes-per-whistle would be a useful conversion rate for reading an Indian recipe and executing it in silent pressure pot.
So, in conclusion, it looks like Jon Conradt's amazing analysis wins. If you missed it, go back and read it. Kudos, Jon!
Sadly, in order for wilbj's estimate to be correct, one would need to be able to maintain a sustained rate of 3.35 headbobs-per-second, which is a bit fast even for Mr. Golla.
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10 comments:
I guess that proves science is better than The Price Is Right method of guessing numbers.
hi Podunk, I had no idea such interesting science was going on over here at longstinger, I had just not seen you on the blogs I hit, so I thought I should swing by. I wish I had known, I love cooking in my pressure cooker, I have issues with planning ahead. I think the number one thing you will have to worry about with a pressure cooker that size is bringing it up to temp to fast. I have two, one about that size and a larger one, an innova. The small one is the hardest one to work with because of scorching the bottom, and nothing is worse than a pressure cooker scorch it is worse than burnt popcorn. I will be following this now, so is the goal cooking Indian food?
Yup, it all started because I wanted to cook some Indian food. I'm an utter novice.
What sort of bottom does your smaller pressure cooker have? Both of my smaller ones (including the Vinod) have a 3-layer construction that's supposed to transfer heat better and prevent some scorching. I have had one or two scorching incidents, mostly involving tomatoes. I think it's the sugars in the tomatoes.
Spanish rice. Mmmmm.
Thanks for stopping by!
So now we need to put this measurement into action to find its utility. This would require 3 parallel meals with the exact same ingredients. One in each of the previous experimental vessels, and a third non-whistler as a control to see how well 2.3m translates to another cooker.
Are we looking for best taste or consistency to the Inod?
Have you published on Wikipedia yet? Planning on including any malware?
I think this calls for a gathering. Buon Apetito!
yep the small one which I hardly ever use is multi layer bottom but not as well as the large one. Cuban ropa vega works great in the pressure cooker and would go nicely with spanish rice. I also make grape leaves in mine, in fact if I start moving the pressure cooker around that is the first question, are we having grape leaves? silly boys.
I'm up for a gathering, but I've got to warn you: I'm no chef; I'm a student.
I could make an apple crisp, though.
I hear rememberedwhoiam does well with south indian quisine. Mmmm? :-)
Indian, Mexican, American, Italian, Antarctic...you name it I'm there!
Made chicken with Chipotle sauce and chiles- all in pressure cooker. pshhht-pshhht!
Thank you so much for doing this! This is very helpful.
I'm thinking of buying a pressure cooker in order to cook some Indian meals but this whole whistle business had me mystified and I was sitting on the fence about whether to get a sleek Kuhn Rikon or an old-fashioned Indian pressure cooker. Now I can opt for the Kuhn Rikon, which is supposedly the "Cadillac of pressure cookers."
I cook Indian food in my presto, nothing but a weighted rocker on top. I have been using 5 minutes per whistle once the rocker starts to rock. This is based on recipes from Neelam Batra's "The Indian Vegetarian" which gives cooking time in minutes not whistles.
Usually scortching is a symptom of too little liquid in the cooker or not using a spacer plate in the bottom to keep the meat off the bottom.
You may want to consider the opossibility that the whistles are the mechanism the cooker is using to maintaining the 15psi. When the pressure rises it lets it off with the Phssssst? If that were the case, three whistles might be three pressure rises and my guess is that the time between whistles will vary depending on what you have in the pot.
Nice to know someone else has been stymied by the reciptes on packaged masalas.
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