Writer：www.firemixer.com Time：2021-09-10 15:11 Browse：℃
How Industrial High Pressure Cooker Works?
Early Industrial Pressure Cooker Pot equipped with only a primary safety valve risked explosion from food blocking the release valve. On modern Industrial Pressure Cooker Pot, food residues blocking the steam vent or the liquid boiling dry will trigger additional safety devices. Modern Industrial Pressure Cooker Pot sold from reputable manufacturers have sufficient safety features to prevent the pressure cooker itself from exploding. When excess pressure is released by a safety mechanism, debris of food being cooked may also be ejected with the steam, which is loud and forceful. This can be avoided if the pressure cooker is regularly cleaned and maintained in accordance with the manufacturer's instructions and never overfilled with food and/or liquid.
Modern Industrial Pressure Cooker Pot typically have two or three redundant safety valves and additional safety features, such as an interlock lid that prevents the user from opening the lid when the internal pressure exceeds atmospheric pressure, preventing accidents from a sudden release of hot liquid, steam and food. If safety mechanisms are not correctly in place, the cooker will not pressurize the contents. Industrial Pressure Cooker Pot should be operated only after reading the instruction manual, to ensure correct usage. Pressure cooker failure is dangerous: a large quantity of scalding steam and water will be forcefully ejected and if the lid separates it may be propelled with considerable force. Some cookers with an internally fitted lid may be particularly dangerous upon failure as the lid fits tighter with increasing pressure, preventing the lid from deforming and venting around the edges. Due to these dangers Industrial Pressure Cooker Pot are generally over-engineered in a safety regard and some countries even have regulations to prevent the sale of non-compliant cookers.
For first generation Industrial Pressure Cooker Pot with a weighted valve or "jiggler", the primary safety valve or regulator is usually a weighted stopper, commonly called "the rocker" or "vent weight". This weighted stopper is lifted by the steam pressure, allowing excess pressure to be released. There is a backup pressure release mechanism that releases pressure quickly if the primary pressure release mechanism fails (e.g., food jams the steam discharge path). One such method is a hole in the lid that is blocked by a low melting point alloy plug and another is a rubber grommet with a metal insert at the center. At a sufficiently high pressure, the grommet will distort and the insert will blow out of its mounting hole to release pressure. If the pressure continues to increase, the grommet itself will blow out to release pressure. These safety devices usually require replacement when activated by excess pressure. Newer Industrial Pressure Cooker Pot may have a self-resettable spring device, fixed onto the lid, that releases excess pressure.
Pressure cooking always requires liquid. Pressure cooking cannot be used for cooking methods that produce little steam such as roasting, pan frying, or deep frying. Sauces which contain starch thickeners can tend to burn onto the interior base of the pressure cooker and may prevent the cooker from reaching operating pressure. Sauces may require reduction and thickening after pressure cooking.
The inner pot of a pressure cooker is generally not filled more than halfway when cooking beans.
Bringing to pressure
Food is placed inside the pressure cooker with a small amount of water or other liquid such as stock. Food is either cooked in the liquid or above the liquid to be steamed; the latter method prevents the transfer of flavors from the liquid. The lid is closed, the pressure setting is chosen and the pressure cooker is placed on a stove on the highest heat (less than high for induction cooking to allow air to be vented). Once the cooker reaches full pressure, the heat is lowered to maintain pressure; timing the recipe begins at this point. Recipes for foods using raising agents such as steamed puddings call for gentle pre-steaming, without pressure, in order to activate the raising agents prior to cooking and achieve a light, fluffy texture.
It takes several minutes for the pressure cooker to reach the selected pressure level. It can take around 10 minutes or longer depending on: the quantity of food, the temperature of the food (cold or frozen food delays pressurization), the amount of liquid, the power of the heat source and the size of the pressure cooker.
The typical pop-up indicator only shows that the cooker has pressure inside, and does not reliably signal that the cooker has reached the selected pressure. A pop-up indicator shows the state of the interlock which prevents the lid from being opened while there is any internal pressure. Manufacturers may use their own terminology for it, such as calling it a "locking indicator."
As the internal temperature rises, the pressure rises until it reaches the design gauge pressure. Timing the recipe begins when the selected pressure/pressure is reached. With first generation designs, the pressure regulator weight begins levitating above its nozzle, allowing excess steam to escape. In second generation Industrial Pressure Cooker Pot, either a relief valve subsequently opens, releasing steam to prevent the pressure from rising any further or a rod rises with markers to indicate the pressure level, without constantly venting steam. At this stage, the heat source is reduced to the lowest possible heat that still maintains pressure, as extra heat wastes energy and increases liquid loss. In third generation Industrial Pressure Cooker Pot, the device will detect the vessel has reached the required cooking temperature/pressure and will maintain it for the programmed time, generally without further loss of steam.
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