how to change safety valve of pressure cooker free sample
Such a valve assembly is known from German laying-open print DOS No. 2,606,676. The pressure relief means thereof consists of a check valve which also serves as a safety valve. It has a valve housing of a resilient material which is fitted into a hole in the cover in the vicinity of the cooking valve aperture. The closure body is designed as a shaft-shaped valve body, transverses the valve opening and supports two spaced valve disks inside the cover as well as a dome-shaped head outside the cover. The head abuts against the valve opening in the pressureless state. As the pressure builds up in the pressure-cooker, however, the valve body is lifted and the upper valve disk closes off the valve opening internally so that the pressure in the cooker can build up. When the pressure becomes excessive, the upper valve disk can move outwardly through the valve opening of the valve housing. This allows steam to escape through the valve opening. The second valve disk preventing the valve body from being blown off the cooker although it does not obstruct the escape of steam. The cooking valve usually comprises a spring-loaded valve and a displaceable pressure indicator for the cooker which is located therein and is also spring-loaded. The springs press against the interior of a cap which is adapted to be screwed on to the valve housing. In the known valve assembly, the cap of the cooking valve has an asymmetrical design on the underside facing towards the cooker cover. It features a guide bevel at this location which reduces its clearance height. In the normal cooking position, the area with the maximum inner clearance height overlaps or overlies the check valve. When the cap is screwed off, the area with a minimum clearance height comes to lie above the check valve over which it can move without obstruction when the head of the check valve abuts against the outer side of the valve seat in the completely pressureless state. If the check valve has closed due to the internal build-up of pressure in the cooker, ie if the upper valve disk abuts against the valve seat, the guide bevel presses the valve body of the check valve downwardly and steam can escape through the check valve. The pressure in the cooker is relieved, whilst the person using the cooker is warned simultaneously by the sound of the escaping steam not to unscrew the cap any farther. If the valve body has been raised only slightly owing to a slight superpressure in the cooker, eg at the onset of pressure build-up, an additional stop which projects into the clearance height prevents the cap from being rotated any farther.
The known valve assembly is expensive to manufacture, since it requires a valve housing and a valve body for the pressure relief means. These parts are expensive to manufacture and to assemble. The cap of the cooking valve is also expensive to produce owing to its asymmetrical shape, and the dimensions of the guide bevel as well as the region of reduced clearance height must be kept within a narrow tolerance range: the valve body must be pressed downwardly to open the valve on the one hand, although on the othe hand this must not be so far that the valve head closes the opening externally. Another drawback is that when the cap is rotated into the open position, the stop jams the head of the valve body and this cannot return to its original position, even when the cooker is not under pressure, until the cap has been turned back somewhat. When the check valve functions as a safety valve, the valve disk cannot automatically turn back any longer due to the valve opening. The cap cannot be screwed off over the projecting valve body either. This makes it impossible to gain access to the valve body and return it to the normal position. Yet another disadvantage is that the valve body of the check valve can only be cleaned thoroughly--quite essential for proper sealing--if it has been snapped out of the valve disk. Since this is complicated and troublesome, such cleaning is frequently postponed or forgotten completely.
A valve assembly comprising a pressure relief means disposed adjacent to the cooking valve is also known from German utility model No. 7,624,730. The pressure relief means is designed as a safety valve in the form of a check valve. The cap of the cooking valve has indents on the periphery thereof. Both valves are spatially associated with one another such that the valve body can be raised adjacent to such an indent only when the cap is in certain positions. The check valve can be closed and pressure built up in the cooker only in this position. When the valve body is in the raised position, ie when pressure has built up in the cooker, the valve body in turn locks the cap of the cooking valve which cannot be rotated. Hence, the vent opening cannot be opened by adjusting the cap. This known valve assembly, which therefore does not correspond to the preamble of the present invention, is expensive to manufacture due to the design of the check valve. It is also difficult to clean, since the steam is dissipated to one side through a cavity in the cooking valve beneath the cap when the safety valve responds to excessive pressure. These cavities are difficult to reach, even after the cap has been removed. Furthermore, the valve body cannot be turned back into its original position until after the safety valve has responded and the excess pressure has been vented off. Only then can the cap be removed from the cooking valve.
The object of the present invention is to provide a valve assembly according to the preamble of the claim which is economical to manufacture, easy to clean and simple to operate in all modes of operation.
The construction of the closure body as a seal disposed on the cap makes it possible to design the vent opening in the form of a simple hole in the cover without any valve housing. Such a hole can be produced during one and the same operation as the hole for the cooking valve. It is easy to clean. The arrangement of the associated seal in the cap gives rise to a constructional design which is simple and easy to clean. This construction of the pressure relief means is made possible by the recognition that the vent opening need only be open to relieve the pressure. An open valve is unnecessary prior to a pressure build-up, since the air being heated up can escape by way of the conventional sealing rings between the pressure-cooker and the cover until the sealing ring abuts sealingly against the cover and cooker wall due to the build-up of pressure. In the pressure relief means in accordance with the invention, the co-operation of the seal and the vent opening permits steam to escape even when the cap is moved minimally towards the venting position. The pressure in the cooker decreases immediately. Moreover, the co-action of the venting opening and the seal generates a warning sound which warns the cook not to opening the cooking valve while the cooker is still under pressure. If there is no seal in the cap, no pressure will build up in the cooker at all.
The seal can advantageously consist of a material which is so resilient that it sealingly closes the vent opening at normal cooking pressure and permits pressure to be vented should it become eccessive. The pressure relief means thus functions as a safety valve as well.
In a preferred embodiment, the seal is designed in an annular shape. It is impossible to insert a ring improperly. The opening is always covered irrespectively of the angular position of the cap in the cooking position.
The annular seal advantageously has an internal diameter which is smaller than the external diameter of the cap section it surrounds. The annular seal is thus seated in the cap region in such a way that it can be neither twisted nor lost. Dirt cannot readily collect between the cap and the annular seal so that the seal does not have to be removed every time the cooker is cleaned.
FIG. 1 indicates the cover 1 of a pressure-cooker. A valve housing 2 is firmly riveted into place in the cover 1. It includes a valve seat 2a against which a valve body 3 is urged by a valve spring 4. This valve spring 4 presses against the inner side of a cap 5 overlying the entire valve assembly and designed as a cap or acorn nut. A pressure indicator 6 is displaceably mounted in the valve body 3. It is pre-biased by a pressure indicator spring 7 which presses against the valve body on the one hand and, on the other hand, against the inside of the cap 5. The cap 5 is adapted to be screwed on to the valve housing by means of a thread 8, thereby determining the tension of the valve and pressure indicator springs.
The cylindrical inner part 5b of the cap 5 forming the nut is surrounded by an annular seal 9 of a resilient material. The annular seal has an internal diameter which pre-biases it on the nut. The brim 5a of the cap extends externally to the annular seal.
The cover 1 has a hole 10 in spaced relation from the valve axis and is located between the internal and external diameters of the annular seal. It serves as a vent opening and is closed by the annular seal 9 during cooking.
FIG. 2 shows the cap 5 from the top. It features a inscribed ring 11 which indicates the setting of the cap relative to an arrow 12 on the cover (not shown).
The afore-described valve assembly functions as follows during cooking: the cap 5 is screwed down to the stop with the inscription "cooking" adjacent to the arrow 12. The valve spring as well as the pressure indicator spring are both pre-biased in this position. The annular seal 9 closes the hole 10. Steam pressure can now build up in the cooker in the known manner once the warm air has escaped between the cooker and the cover as mentioned above. The cooking pressure is chosen by regulating the supply of heat in response to the position of the pressure indicator 6. At the conclusion of cooking, the cap 5 is turned half a turn to the "venting" position. This causes the annular seal to release the hole 10, the steam can escape and the pressure is relieved. The venting is continuous and dependent on the speed of rotation.
If the pressure indicator is not observed during cooking, i.e. if the supply of heat is not turned down at the proper time, thus causing the pressure in the cooker to become excessive, the steam can escape through the hole 10. This gives off a warning whistle and deforms the annular seal 9. Should the generated steam still be excessively high, the valve body 3 is lifted off its seat 2a.
I don’t deny that raising pressure too quickly results in undercooked food. I am just questioning, and trying to understand why it is so. I don’t think you fully understand the reason behind it either.
Again, no. the overall pressure is determined by the pressure regulating mechanism. Not by what is inside. That is a (nominal) 15 psi. Regardless of whether it is air, steam, a combination or something else. Once the gauge indicates 15psi, then the overall pressure is 15psi. Not something lower. Temperature is another question. At the start of this, I would have said it remains the same as for a given volume, pressure is proportional to temperature (Avogadro’s Law), but I haven’t seen anything that clearly backs me (or you) up, so now I am not so sure. Hopefully when I get a chance to read further I will get it clarified. Ideally I will find experimental evidence. It’s a shame I no longer know people who would be able to set up an experiment for me.
Observed fact: Food cooked in a pressure cooker brought to pressure at full power on an induction stove is under done if cooked for the recommended time
5. the pot does not heat up properly in the shortened time to pressure so heat that would otherwise go into the food is diverted into heating the container.
Anyway, This is getting way too far off topic (PC trouble shooting) so I won’t go any further here. If you want to continue the discussion perhaps we should move it to its own thread in the forum.
There is no international pressure cooker organization that sets a global standard. Pressure cooker UL Rating, which is an American Appliance Testing standard, only states that a domestic pressure cooker “operate at a nominal pressure of 15 psi (103 kPa) or less.” While in Europe the CE rating, the equivalent to the American certification, state that a “simple pressure vessel” can be above .5 bar (7.2 psi) and below 50 bar (720 PSI) . American manufactured pressure cookers adhere to a standard for pressure canners set by USDA in 1917 – 15 psi.
While some European pressure cookers are sold world-wide many of these manufacturers make a separate model specifically for the American market that reaches 15 psi. Some European manufacturers are switching to a single model distributed world-wide that reaches 15 psi. At the writing of this article, American pressure cooker manufacturers only sell their pressure cookers in the United States.
All recipes and cooking time charts on this website are written to accommodate both “standard” and “non-standard” pressure cookers. When necessary, times are written in a range – standard pressure cookers should use the shorter cooking time (13 minutes) and non-standard pressure cookers the longer (20 minutes).
This comes down to the difference in measuring systems between the United States (imperial) and the rest of the world (metric). Pressure in the rest of the world is measured inkilopascals (kPa) and bars while the U.S.it is measured with pounds per square inch (psi).
European manufactured pressure cookers are designed to cook at 1 bar or 100 kpa (metric pressure measurements) and that translates to 14.5 psi (this is rounded up to 15 psi) but American manufactured pressure cookers are designed to reach a full 15 psi (see below, for information on electric pressure cookers).
The rise in pressure inside the pressure cooker directly correlates to the rise in boiling point – the maximum cooking temperature that can be achieved at a given pressure.
The pressure cooker adds pressure above the current atmospheric pressure. Since there is a pressure difference in the atmosphere between one altitude and another, the pressure cooker’s pressure will vary accordingly.
Moving up in the atmosphere, or going to higher altitude, the atmospheric pressure decreases. So in Denver Colorado (about 5,000 feet) the atmospheric pressure averages only 12.2 psi- add 15 psi of pressure generated by the cooker and there the food is cooking at just 27.2 psi of absolute pressure -almost 3 psi less pressure than pressure cooking at sea level!
The same 15 psi pressure cooker will cook 15 psi in San Francisco, California (sea level) but only 12.5 psi in Denver, Colorado (5,000 feet). Now, “standard pressure cooker” has become “non-standard” in Denver. This means that the recipes will need the same timing adjustments used for non-standard pressure cookers (see pie chart, above).
Increase pressure cooking time by 5% for every 1000 ft above 2000 ft elevation (see table, below). Multiply the recommended cooking time by the number on the table. The result will likely be a decimal value just round that up to the next minute.above...increase by..or multiply by..
The transformation from a Renaissance “bone digester” invented by French scientist Denis Papin (in 1689) to pressure canners (1905) and finally to the pressure cooker we know today began in 1926. The Home Exhibition in Paris introduced the first model for home use. The pressure cooker made it out of Europe and into the United States via the 1939 New York Fair where the National Pressure Cooker Company launched the first U.S. model.
Aluminum pressure cookers took off in the U.S. and many companies began producing them. Then, America’s involvement in WWII halted the production of pressure cookers and their factories were dedicated to producing munitions for the overseas war.
Once the war ended, European and American pressure cooker manufacturers began to develop and produce pressure cookers independently from each other. While in America unscrupulous factories made and sold sub-standard pressure cookers – that eventually went on to mar the cooker’s reputation and halt innovation- European manufactures continued to develop, perfect and innovate their designs adding multiple redundant safety mechanisms, selectable pressure levels and more features.
The 90’s started the trickle of European manufactured pressure cookers, and their features into America. It’s also when the patent for the first electric pressure cooker was filed by Chinese scientist, Mr. Yong Guang Wang. The electric pressure cooker was developed independently from stovetop pressure cookers in that they were based on the ever-popular electric rice cookers (hence the resemblance) and are manufactured in a range of pressures – depending on the manufacturer or design team.
At the time of the writing of this article, most electric pressure cookers reach 15 psi but they do not cook at 15 psi. As illustrated by the graphic below – electric pressure cookers reach 15 psi briefly during the warming process.
Electric pressure cookers build pressure up to 15 psi but then maintain a lower pressure during the cooking. In the graph below the “operating pressure” is 11.6 even though the cooker reaches 15 psi while it’s building pressure. “Operating Pressure” is the true pressure at which an electric pressure cooker cooks.
Most instruction booklets have this information written in them. The number may be written in kPa, bar or PSI (use the table in this page to decode the approximate PSI). There may be several terms used in conjunction with those numbers and they include:
Valve Release Pressure – the pressure at which the main regulating valve releases pressure (2 to 4 psi more than the operating pressure depending on the manufacturer).
Electric pressure cookers will have the “valve release pressure” written in very small text on the underside of the pressure release valve either on the plastic housing, or the metal part of the valve.
This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data.
This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data.
Pressure cookers are quite common in kitchens these days because they save time and effort while in cooking. They used to be dangerous, but not anymore, thanks to improved technology, advanced mechanisms, and safety features that have given an entirely new dimension to cooking.
However, like every other tool, a pressure cooker can encounter issues that can impact the cooking time and the quality of food, causing you unnecessary frustration. What would you likely do? Check the instruction manual and search for troubleshooting steps.At times, user manuals may not be able to resolve the problem, because of the following reasons:
This is the main reason why this particular post includes every problem a pressure cooker can develop. Starting with the basic steps on how a pressure cooker should be used, we’ll take you through the common functioning issues, followed by some critical ones. This post will provide the insight on technical and functional aspects of modern-day pressure cookers. So, let’s get started right now!
Below are the steps showing how you should operate your pressure cooker under normal circumstances.Pour the liquid into the pressure cooker up to the minimum level indicated in the manual. Add the desired food item and lock the lid if required.
Choose the pressure according to the food (normally indicated in the manual). Modern-day pressure cookers, especially electric cookers have pre-determined programs and time. So, you can use this feature as well.
After 10 to 15 minutes of pressure cooking, the following processes will have taken place:The air and steam will escape out of the valve indicating that the cooking contents are boiling.
You have to turn on the digital timer to cook the food at the desired pressure. In automatic electric pressure cookers, there is a count-down feature that automatically maintains the pressure for a certain time.
At the end of the cooking, the pressure release takes place. It depends on upon the recipe what kind of pressure release method suits it. The pressure releases as the steam comes out through the pressure release valve.
Steam leakage is the most common problem in pressure cookers that causes problems in pressure buildup. It takes longer for the pressure to reach the desired limit, and when it does, it cannot remain constant for the specified period.
Wash the gasket in cold water and fix it back in the correct manner. Follow the directions while fixing the gasket back to its position.Damaged Gasket or Old Valve
Sometimes the gasket gets damaged. With the passage of time, the pressure valve loses its efficiency and effectiveness. As a result, you don’t get the right pressure buildup for cooking.Always check the gasket and pressure valve for damages, and replace them as soon as possible.
There are several different issues why your pressure cooker may not properly cook the food within the estimated time, such as:You’ve filled too much food or water
If you’re a new user, you might easily be scared seeing water coming out of the valve, but it’s not a big thing. However, this is another common issue that can cause operational issues for a pressure cooker.
This particular problem mainly occurs in pressure cookers that have pressure regulating weights. You can see the water dripping out and vapors accumulating around the rim during the pressure buildup. As soon as the pressure is achieved, the vapors go away.
Anyhow, if you have a different model and still having the same issue, it may be because of food particles accumulated inside the vent pipe. To avoid this issue, clean the valves and the vent pipe regularly.Difficulty in Opening the Lid
Another common problem with pressure cookers is, the cooker lid gets tight and remains jammed even after the heat is turned off. It is often caused by the internal pressure of the pressure cooker. The pressure release may be insufficient and ends up jamming the lid.
If the lid remains jammed, remove the pressure valve and allow the pressure cooker to heat on high. That will release the pressure, and the lid will loosen its grip.
There are many reasons for pressure cookers not achieving the desired pressure level. Each of them, with their solutions, is mentioned below:The Lid: The lid of the cooker must be positioned accurately. In that case, remove and refix it in the right manner. If the problem persists, replace the lid according to the instruction manual.
The Gasket: There may be a problem with the gasket’s positioning. You need to remove the gasket by removing the lid first. Clean the gasket properly then refix it in the manner specified by the instruction manual. The gasket may deteriorate with excessive cooking, spattering oil, and acid foods. If there are signs of wear, a replacement may be needed.
The Locking Mechanism: Pressure cooker may not be attaining the right pressure because of the locking mechanism. Or, it may not have been locked properly. This problem occurs in pressure cookers that do not have a self-locking feature. Check the locking mechanism of your pressure cooker, thoroughly before putting the food in it.
The Rim: Leakage may also occur due to a damaged rim. They get damaged when you rap your spoon against the rim. If you have a stainless steel pressure cooker, use steel wool to remove scratches and stains on the rim.
The Valve: Another reason why the specified pressure level is unattainable is due to the improper placement of the pressure valve. Improper cleaning of the valve causes this. So, always clean and fix the valve of the pressure cooker before cooking.
Old Gasket and Valve: As discussed above, the gasket and pressure valve must be checked regularly before using the cooker. Normally, you should replace the gasket and other pressure cooker components made of silicone or rubber every 18 months.
The Liquid: Pressure cookers have limited capacity for food, and they always need space to build pressure. A pressure buildup will take up to 30 minutes to reach the desired pressure if there is too much liquid inside the cooking pot. Follow the instructions while adding the liquid to keep it at the minimum level.
The Food: Normally, the instruction manual has information about how much ingredients you can put inside your pressure cooker for a certain recipe. Too much ingredients can cause a delay in pressure buildup, or the pressure may not be achieved at all. In general, if you’re filling grains, fruits, and legumes, keep your pressure cooker half-full. For all other recipes, maintain 2/3 of the filled space.
Cold Items: Either allow the frozen food to defrost before pressure cooking or plan for longer times. Frozen ingredients can easily increase the pressure cooking time up to 30 minutes.Desired Pressure Cannot be Maintained
Any of the following issues may cause difficulty maintaining the pressure you want:Old or Damaged Gasket: The gasket of the pressure cooker needs to be replaced every 18 months. If your pressure cooker consists of other rubber or silicone parts, replace them periodically.
Problem with the Valve: Pressure valve needs to be secured properly to create pressure buildup and maintain the desired pressure for a certain period of time. Pressure cannot reach the desired level with an old or worn out pressure valve. So, always clean the pressure valve and replace it every 18 months.
External Temperature:This is the main issue with stove top pressure cookers in which you either reduce the heat too much or too soon. Read the instruction manual thoroughly to know the exact time to turn down the heat. If you think you’ve turned the flame lower than the required limit, turn it back to high and allow the pressure to build. Then reduce the heat slowly to the desired level.Pressure Valve Sprays Foam or Food
It can happen because of the following reasons.The opening method: The main reason why a pressure valve sprays foam, you’ve used the wrong opening method. If it sprays foam, there is likely legumes, fruits, and grains in the pressure cooker. For these ingredients, the only way to open the pressure cooker is through natural release method. For other recipes, follow the instruction manual.
Thickeners: If you have included thick liquid or flour in your recipe, the pressure valve may spray the food out. It happens because of the food binding with the steam, and when the pressure is released, some food particles might also come out.
Filling More than Limit: If the pressure cooker is filled more than its capacity, food particles will mix with the steam and spray out when the pressure is released. So, keep the pressure cooker 1/3 empty for all kinds of foods except for fruits, legumes, and grains as they should half-fill the cooker.Pressure Cooker Releases Steam More than it Normally Does
Steam is released before pressure cooking and after it… there are few reasons why your pressure cooker releases too much steam in either stage.Valve adjustment: If you notice that the valve is releasing too much steam, adjust the valve.
Too Much Heat: Excessive heat applied to the pressure cooker may cause too much steam release. In that case, let some pressure out then reduce the heat.Food is not Cooked Properly
Your food may be undercooked or overcooked because of the timing, regardless of the model you use. Follow the instruction manual and note the amount of time required for different recipes to cook properly. There may be other reasons as well.Heat During Pressure Cooking: In stovetop pressure cookers, if you set the heat too high, the food can be overcooked, dried, or burned. Too much heat builds up extra pressure and causes the food to burn or dry. So, if you experience it during cooking, lower the heat to the minimum level.
Burner Size: Another problem with stovetop pressure cookers is, if the burner is wider than the size of the pressure cooker, your food may overcook or burn. Always, use the burner according to the size of your pressure cooker.
Well, if you have installed a new gasket then you have to make sure it’s installed the right way. While installing it in the lid, make sure that the “Right Side” of the gasket points upward. If the problem persists, check the structure of your pressure cooker looking for signs of “warping”.
If you have a vintage aluminum pressure cooker, it may have this problem. Stainless steel pressure cookers don’t often face this issue, and they don’t damage as often when compared to their aluminum counterparts.It may have a warped lid: you may not detect the warping at first sight, but even the slightest warping can cause the steam to leak. It may have been due to overheating or aging of the material. Or, the pressure cooker may have been dropped in past.
The base unit has a damaged rim: This is caused by dents, dings, scratches and abrasive cleaners. If the rim gets damaged, it may not allow adequate sealing. In this situation, you have to either replace these parts or buy a new pressure cooker.Gasket Stuck to the Lid
If the gasket gets old and needs replacement, there are chances that further heating will melt it and it will stick to the metal. If the gasket is exposed to high or prolonged heating, it can stick to the lid. In this situationUse liquid dish soap, vinegar or hot water to soak the gasket.
Using a plastic pad, try to loosen the gasket carefully, so that you can remove the entire gasket later. If that seems impossible, try to remove off in pieces, as much as you can.Melted Gasket
To remove a melted gasket or one that’s bonded with the metal, apply WD-40, “Gum-Out” or “Goo-Gone.” While applying these solvents, read the instructions carefully. They should be a last resort and not used on materials that would interact with the product.
The metal sealing and the pressure cooker lid should not be scratched or damaged while removing the gasket. So, avoid using scrapers, sandpaper, or abrasives on these metal surfaces.Aluminum Pressure Cooker Having Stains
If you have an aluminum pressure cooker, you have to be careful while cleaning it. Alkali solutions can harm and discolor aluminum. Baking soda is a mild alkali and ammonia solvents are medium strength alkalies that can cause stains on aluminum pressure cookers. You can remove light stains and small discoloration by cooking acid foods in an aluminum pressure cooker. For stubborn stains, you can apply the following method.
If you live in a location where tap water contains minerals, your aluminum pressure cooker may develop mineral stains. That happens, because the minerals from the water deposited inside the aluminum pan, react with the soap, detergents and the fats from the food and produce stains on the surface.
Heat tint is a dark and permanent discoloration on stainless steel with purple or blue color appearing prominently. It is caused by any of the following issues:Too much heat is applied to the pressure cooker
Although the heat tint is permanent, it may fade with the passage of time. Mild discoloration does not affect the usefulness of the pot, while severe tints can cause functional issues in your pressure cooker.