Safely discharging a clogged iSi charged whipper

[sygyzy]

Last night I tried my hand at making a 40 second cake using Adria's method. I make a batter with ground pistachios, sugar, eggs and flour and filled a 1/2L ISI whipper canister. I put it in the fridge and when dessert came, I charged it with two nitrogen cartridges. I made many mistakes here - used mixer instead of blender to mix, did not pass through a sieve, chilled for too long which made the batter thick.

Long story short, nothing came out. The nozzle was clogged and because of the pressure, the cap was on tight. I was frustrated because I had guests over and they were waiting for dessert, not really aware of what was happening in the kitchen. I stupidly started unscrewing the cap, pausing to shake the canister hoping to move the batter around and promote venting. I also kept pumping the lever and every 30 seconds I would get some to sputter out.

My fear during this whole ordeal is that I reach the end of the threads and the cap explodes off, taking my hand with it. Or an eye. In the case where an isi charged whipper is clogged, is there any way to vent it safely?

[jk1002]

I did vent it in the past when I used it to carbonate gels or gin or grapes and so on. I just did it like I would vent a bottle of soda that was shaken. Just screw it up a little bit until you hear it hissing, not all the way, then close quickly again and so on. If you leave it open too long the batter may come out, depends how thick it is.

[Kayakado]

I would think seriously about wrapping it in a heavy bath towel before unscrewing that lid. If it did come off the heavy towel might prevent it from too much collateral damage

[dougal]

.. The nozzle was clogged and because of the pressure, the cap was on tight. ... I stupidly started unscrewing the cap, pausing to shake the canister hoping to move the batter around and promote venting. I also kept pumping the lever and every 30 seconds I would get some to sputter out.

My fear during this whole ordeal is that I reach the end of the threads and the cap explodes off, taking my hand with it. Or an eye. In the case where an isi charged whipper is clogged, is there any way to vent it safely?

I don't believe that the stored energy would be greater than in a Champagne bottle.

Even with two charges into a 1 litre whipper.

Significant, but hardly extreme.

The way to release the pressurised gas is by SLIGHTLY unscrewing the cap.

This should allow the sealing washer to lift slightly and allow the gas to escape down the thread -- exactly like gently cracking open a fizzy drink (US 'soda') bottle.

As long as SOME gas is escaping, energy is being discharged, and the thing is becoming safer.

So unscrew it ONLY until it whistles or hisses, and then let the gas continue escaping slowly -- it'll probably take seconds, rather than minutes.

When it stops hissing, unscrew it a little further. If hissing restarts, keep the cap in that position until it stops, and then unscrew it a little more.

Be patient - it'll take much less than a minute!

The pressure should be completely discharged long before you reach the end of the thread on the cap.

BUT -- there is no need or point in shaking the thing!

In fact shaking it is going to be counter-productive.

You'd prefer to keep the 'batter' out of the threads - it could block that gas escape route at least as easily as the discharge valve.

Rather tha shaking it, I'd prefer to let it stand upright for a few minutes before starting to loosen the cap.

Sure, wrapping the thing in a towel will contain any potential mess (and the unlikely, unless you have completely batter-clogged the thread, event of the cap escaping).

I wouldn't lean over the thing while unscrewing it, and I'd prefer to do the job outdoors. (Apart from anything else, you don't want to risk finding the whole process "unaccountably amusing" ...)

[David A. Goldfarb]

If you want to release the pressure and start over, I'd put it with the nozzle up and pump the handle to release the nitrous oxide without releasing the contents. A little of the batter will spatter, so you could put your hand over the nozzle or cover it with a towel, but you can release all the pressure that way without opening it. I've never gotten into a situation where this didn't work.

[sygyzy]

If you want to release the pressure and start over, I'd put it with the nozzle up and pump the handle to release the nitrous oxide without releasing the contents. A little of the batter will spatter, so you could put your hand over the nozzle or cover it with a towel, but you can release all the pressure that way without opening it. I've never gotten into a situation where this didn't work.

Thanks everyone for your help. It looks like I did the right thing by slowly unscrewing it. Thank you too David for your attempt but I came here to post after trying the obvious answer - using the handle to release the pressure.