question: How do vacuum holders work? How are they able to hold heavy items?
comment: Another thing to just keep in mind is a high quality vacuum will provide about 15 pounds per square inch of pressure. So if you have a 1' circle to lift with, you get roughly 1700 lbs of force. Conversely, this is why pressure vessel doors can be so dangerous. If you have a 3' door pressurized to one pound/sqin over atmosphere, you get 1000 pounds pushing on it. If you accidentally overpressureize it to 10 lbs/sqin, now you have 10000 lbs, enough to shear off your bolts holding the door closed if they're not made for that purpose. This has killed people. :(
passages: Section::::Structure and technical requirements.:Machine base.
  
  The machine base acts as the stand for a vacuum filler. For hygiene reasons, bases are made completely of stainless steel. The compact machine base is designed to ensure that it can be moved easily using lifting equipment.
  
  Section::::Structure and technical requirements.:Lifting device.
  
  Lifting devices allow the hopper to be loaded using standard trolleys. They can either be fixed onto the vacuum filler or a mast type lifting device can be positioned separately next to the vacuum filler. Lifting devices can be driven hydraulically or electrically.
  
  Section::::Structure and technical requirements.:Control and drive systems.
   Air dams can be nothing more than masking or packing tape, a flat stock of just about any material, or anything else that can resist the vacuum force sufficient to vacuum applied and thus clamping force. Also, the air dams may provide a closer seal that light vacuum applied to delicate parts can be used.
   Section::::Applications.
   A vacuum table is similar to a "Magnetic Clamping Table" in use, typically, to the same end as a vacuum table except instead of vacuum, the magnetic table uses electromagnetic attraction to restrain ferrous materials to the table facilitating ease of access for modern machining. A vacuum table, of course, is not limited to ferrous materials.
   Section::::Technology.
   Vacuum chambers can be constructed of many materials. "Metals are arguably the most prevalent vacuum chamber materials." The strength, pressure, and permeability are considerations for selecting chamber material.
  
  Common materials are:
  
  BULLET::::- Stainless Steel
  
  BULLET::::- Aluminum
  
  BULLET::::- Mild Steel
  
  BULLET::::- Brass
  
  BULLET::::- High density ceramic
  
  BULLET::::- Glass
  
  BULLET::::- Acrylic
  
  BULLET::::- hard steel
  
  Section::::Vacuum degassing.
  
  "Vacuum degassing is the process of using vacuum to remove gases from compounds which become entrapped in the
   Section::::Types and construction.:Dump valves.
   Section::::System design.:UHV manipulator.
  
  A UHV manipulator allows an object which is inside a vacuum chamber and under vacuum to be mechanically positioned. It may provide rotary
   Air dams are not entirely required in the use of a vacuum table but they can be when the source of vacuum is limited. As a vacuum pump, generally, is designed for high vacuum as opposed to high volume, air dams can be used, again, to increase clamping force. A source for vacuum in some applications may be as simple as a typical shop vac or vacuum cleaner, in a light application. Vacuum pumps are the usual vacuum source.
   Pneumatic or pneumatic wet/dry vacuum cleaners are a specialized form of wet/dry models that hook up to compressed air. They commonly can accommodate both wet and dry soilage, a useful feature in industrial plants and manufacturing facilities.
  
  Section::::Modern configurations.:Backpack.
  
  Backpack vacuum cleaners are commonly used for commercial cleaning: they allow the user to move rapidly about a large area. They are essentially small canister vacuums strapped onto the user's back.
  
  Section::::Modern configurations.:Hand-held.
   Section::::Applications.
  
  Today there are different types of conveyor belts that have been created for conveying different kinds of material available in PVC and rubber materials. 
   Thermoformed plastics can be customized for size, color, clarity, and shape to fit products perfectly, creating a consistent appearance. One of the most commonly used thermoformed plastics is PET, known for a high-strength barrier resistant to outside tampering and an ease of molding into designated designs and shapes. Some common uses for Thermoforming in vacuum packaging include:
  
  BULLET::::- Fresh and marinated meat
  
  BULLET::::- Sausage
  
  BULLET::::- Cheese
  
  BULLET::::- Candy / chocolate
  
  BULLET::::- Grain
  
  BULLET::::- Grab-and-go snacks (beef jerky, snack sticks)
  
  BULLET::::- Pharmaceutical and medical products
  
  BULLET::::- Coins / collectables
  
  Section::::Shelf life.
   The quantity of inflation air may be varied in accordance with the particular properties and requirements of the package contents. Dunnage bags are commercially available in various sizes and designs, ranging from spheres, standard cushions to corner and edge cushioning and tubular cushioning. Dunnage bags can be used to stabilize, secure, and protect cargo during all sorts of transportation. Dunnage bags are placed in the void between the cargo. Dunnage bags can be used in all modes of transportation. Besides being usable in all modes of transportation, almost every type of cargo can be secured with the use of dunnage bags, including break bulk and palletized cargo, coils, barrels, cases, and crates.
   A vacuum table consists of a typically flat rigid surface with small holes to move air from under a workpiece, as to apply varying vacuum from between the desired workpiece and table to maintain a clamping force greater than that needed to machine a part, generally, in a mill, lathe, EDM (Electro-Discharge Machine), pantograph or any other commonly used machine in a machine shop environment.
  
  The main purpose of the vacuum table is to allow full access to all sides of a machined part, except the side in which the part contacts the vacuum table.
   BULLET::::- Holding devices: Holding devices in the field of sausage production are used for automatic sausage linking. A holding device comprises a rotating linking nozzle and an appropriate sausage casing brake. The movement of the linking nozzle is achieved by a drive integrated into the vacuum filler. The sausage casing brake ensures that the sausage casings are extracted evenly, thus creating equal portions.
  
  BULLET::::- Hanging lines:
   Section::::Typical applications.
  
  Original equipment manufacturers (OEMs) utilize heavy gauge vacuum formed components for production quantities in the range of 250–3000 units per year. Vacuum-formed components can be used in place of complex fabricated sheet metal, fiberglass, or plastic injection molding. Typical industry examples besides product packaging include: fascias for outdoor kiosks and automated teller machines, enclosures for medical imaging and diagnostic equipment, engine covers in a truck cab or for construction equipment, and railcar interior trim and seat components. Vacuum formers are also often used by hobbyists, for applications such as masks and remote control cars.
  
  Section::::Common problems.
   Vacuum chambers are used to test the ability of a package to withstand low pressures. This can be to:
  
  BULLET::::1. Determine the ability of packages to withstand low pressures that might be encountered. this could be in an air shipment or high altitude truck shipment.
  
  BULLET::::2. A laboratory vacuum places controlled stress on a sealed package to test the strength of seals, the tendency for leakage, and the ability to retain sterility.
  
  Section::::Shock and impact.
   A vacuum chuck is primarily used on non-ferrous materials, such as copper, bronze, aluminium, titanium, plastics, and stone. In a vacuum chuck, air is pumped from a cavity behind the workpiece, and atmospheric pressure provides the holding force. Vacuum produces a hold down pressure of at sea level, decreasing at higher elevations where the atmospheric pressure is lower. The decrease in holding pressure is roughly 0.5 psi per 1000' above sea level.
  
  Section::::Mounting methods.
  
  Connecting chucks to the spindles or tables of machine tools or power tools has been accomplished in many ways over the years.
   Vacuum packing greatly reduces the bulk of non-food items. For example, clothing and bedding can be stored in bags evacuated with a domestic vacuum cleaner or a dedicated vacuum sealer. This technique is sometimes used to compact household waste, for example where a charge is made for each full bag collected.
  
  Vacuum packaging products, using plastic bags, canisters, bottles, or mason jars, are available for home use.
   BULLET::::- Torr-Seal, or its generic equivalent Hysol-1C (USA brand name) or Loctite 9492 (EU brand name), is an epoxy with resin and hardener for use in vacuum environments. It will begin to degrade at high temperatures but otherwise is very stable with very little outgassing. Other vacuum-rated epoxies are also available. For mounting or joining thin metal foils, grids, or other small pieces that are not expected to undergo stress, silver or gold paste may be used as an adhesive. After fixing the material(s) with silver paste, the piece must be baked (to  200 C) in air for  24 hours to remove volatiles prior to insertion into vacuum.
   The vacuum mattress is put on a stretcher or possibly on a long spine board. The straps are put under the mattress, along its side, so they do not reach the ground. Then, the polystyrene balls are distributed evenly through the mattress by shaking its surface. (A section with fewer balls would be less rigid, conversely if balls are concentrated at any given point this becomes more rigid.) A sheet is put on the mattress, folded so it will be possible to pull it to wrap the casualty into using an S-fold and finally a team member should double-check the pump (manual or electrical) is set to either pump air out of the bag.
   Materials for use in vacuum
  
  Materials for use in vacuum are materials showing very low rate of outgassing in vacuum, and, where applicable, tolerant to the bake-out temperatures. The requirements grow increasingly stringent with the desired degree of vacuum achievable in the vacuum chamber.
   Section::::Medical uses.:Preparation of the vacuum mattress.
   Section::::Structure and technical requirements.
   BULLET::::- Some elastomers have sufficient vacuum properties to be employed in vacuum o-rings:
  
  BULLET::::- NBRs, (Nitrile rubber), commonly used for demountable vacuum seals (bakeable only up to 100 °C).
  
  BULLET::::- FKMs (FPMs), (Viton) is used for demountable vacuum seals. It is better for lower pressures than nitrile rubber and chemically much more inert. It is bakeable to 200 °C.
  
  BULLET::::- FFKMs (FFPMs) very low out-gassing similar to Teflon and withstands baking temperatures up to 300 °C, while chemically one of the most inert sealing elastomers.
  
  Section::::Materials for vacuum use.:Glasses and ceramics.
  
raw_presuppositions: Vacuum holders are not strong enough to hold heavy items.
raw_corrections: A high quality vacuum will provide 15 pounds per square inch of pressure.