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A whipped cream charger (also called whippits, whippets, nossies, nangs, chargers, or, when empty, robot poo) is a steel cylinder or cartridge filled with nitrous oxide (N2O) that is used as a whipping agent in a whipped cream dispenser. The narrow end of a charger has a foil covering which is broken to release the gas. This is usually done by a sharp pin inside the whipped cream dispenser. The nitrous oxide in chargers is also used as a recreational drug, and to power model rocket engines.
The cylinders are about 6.3 cm (2.5 inches) long and 1.8 cm (0.7 inches) wide, and they are rounded at one end with a narrow tip at the other end. 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.
In Europe, where production and use of whip cream chargers originated, there are presently 3 factories involved in its production. Standard size for whip cream chargers is 8 grams of nitrous oxide per cartridge. Whipped cream chargers are intended for low-volume or occasional use, such as home kitchens, restaurants, and coffee shop applications. For very high volume commercial use, there do exist regulated tank systems for filling much larger containers and dispensing more whipped cream. These are more desirable if volume is in excess of a production level of 10 liters per hour. Whipped cream 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.
Nitrous oxide is used because it migrates easily into the cream, and does not cause the cream to oxidize while it is in the can. Cream must have a minimum fat content of 28% to produce whipped cream with a dispenser. 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 flavorings/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 fat-soluble 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 then 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 and comes out of the solution — just as 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.
Because of their availability, chargers are usually the method of choice for users seeking to use nitrous oxide recreationally. Tanks of medical grade nitrous are difficult to obtain, and auto-grade nitrous contains dangerous neurotoxins. Chargers are cheaply available in many stores and online.
To inhale from a charger, users either fill a balloon using a cracker, or fill an empty whipped cream dispenser and inhale from it. A cracker is a small device, usually made from metal, which contains two halves. The bottom half is where the charger is placed, and the top half has a pin which pierces the foil of the charger. The top half screws onto the bottom half, and then releases the gas out the top. Using a balloon with the cracker is important because when the gas is released from the charger it is extremely cold and can cause frostbite in the lips, tongue, throat, and lungs, so the gas is allowed to warm up inside the balloon before inhaling.