Whipped-cream chargers

A whipped cream charger is a cartridge designed to deliver nitrous oxide in a whipped cream dispenser. The contents of chargers are also inhaled for recreational purposes by those unable to obtain nitrous oxide through other means. Chargers are usually called whippits (sometimes spelled whip-its or whippets) by recreational users. iSi brand chargers are considered to be the best quality chargers for gourmet and other use, due to their strict manufacturing procedures and repeated cleanings during manufacture (to prevent toxic machining oils from remaining in the charger).

Whipped cream chargers are steel cylinders rounded at one end with a narrow tip at the other. They are typically painted silver, lavender, or blue, and nominally 6.3 cm (2.5 inches) long and 1.8 cm (0.7 inches) wide. The chargers' walls are about 2 mm (about 1/16 inch) thick to withstand the great pressure of the gas contained within. Their interior volume is 10 cm³ and most brands contain 8 g of N₂O under pressure. Used chargers are non-refillable but 100% recyclable, where steel recycling programs exist.

To use a whipped cream dispenser, one starts by following a recipe — typically 1 cup of heavy cream, 2-3 tablespoons of sugar, and any flavourings/colorings as desired. The device is capped and one or two chargers are discharged into the unit, depending on its size. These pressurize the device with nitrous oxide and cause the gas to dissolve into the cream, just like carbon dioxide dissolves into water to create soda water. Shaking the dispenser a few times helps the gas dissolve. The dispenser is now ready for use.

When the cream dispenser's valve is opened, the cream is forced out of the nozzle by the high pressure. However, when the pressure is released, the dissolved gas turns to bubbles (see Charles' law) and comes out of the solution — just like how opening a soda bottle results in the formation of a head of bubbles. These expanding bubbles instantly transform the cream into a frothy, whipped state. Nitrous oxide is bacteriostatic (prevents bacteria from growing) and a charged cream dispenser can be kept in the refrigerator for up to 2 weeks.

Cheaper brands of whipped cream chargers contain less gas, usually requiring the cream whipper's operator to use two chargers where one would normally suffice. Cheaper brands also may not be as clean inside after being filled and sealed, resulting in toxic oil mists being sprayed into the cream (or recreational users' lungs) when the charger is opened and depressurized. EZ-Whip brand chargers are notorious for machining oil contamination and should be avoided for any use.

Chargers are designed to be opened with a device that punctures the thin metal seal at the narrow end of the tube. Whipped cream dispensers have this integrated into the device's cap; recreational users employ a cracker, typically constructed from plumbing hardware, to achieve the same result. The escaping gas expands considerably and cools down, which is not a problem in a cream whipper but can result in freezing burns and frostbite if opened directly into someone's mouth.

In addition to their primary use (making whipped cream), chargers can be used as a cheap source of nitrous oxide for small, powerful model rockets. Nitrous oxide breaks down into nitrogen and oxygen at elevated temperatures, such as those found in automotive and rocket engines. It greatly improves combustion by making more oxygen available to the combustion process. Model rockets designed to be assisted with whipped cream chargers can thus fly much higher and faster than conventional designs of the same size. Nitrous oxide for car racing is supplied in much larger tanks, as using tiny cream chargers to power an automotive engine would be an expensive pursuit. Automotive nitrous is usually mixed with a small amount of sulfur dioxide, a noxious, irritating gas, to discourage recreational use.

Small whipped cream chargers are intended for low-volume or occasional use, such as home kitchens. For commercial use, there exist regulated tank systems for filling much larger containers and dispensing more whipped cream. These are more economical for high-volume users, such as ice cream shops and dessert caterers.

External links

• Microscale Gas Chemistry: Experiments with Nitrous Oxide (http://mattson.creighton.edu/N2O/)
• Micro-Hybrid - nitrous oxide-assisted class D model rocket (http://www.hpr.org.uk/mhybrid/index.htm)
• How Stuff Works - Why does nitrous oxide improve engine performance? (http://www.howstuffworks.com/question259.htm)
• Gruenewald Manufacturing, makers of high-volume dispensers for ice cream parlors (http://www.whipcream.com/corpinfof.htm)
• The Vaults of Erowid -- Nitrous Oxide (http://www.erowid.org/chemicals/nitrous/)