question: why do the majority of plastic containers/tubs/bottles have a small ‘ramp’ going downwards in the bottom of them.
comment: Pretty sure its to keep it moving along the production line and to keep it still at the appropriate time it gets filled up and the cap screwed on.
passages: The construction of a bucket bong (or simply a "bucket") calls for a large plastic bottle (about ), a large bucket or other container that both the bottle and a large amount of water will properly go into, a Hex Bit Socket used as the bowl, an aerator screen cut to fit the bowl, and a large bucket or container. The large plastic bottle's base is cut off, and the bottle's cap has a small hole in the center which will eventually hold a bowl. The screen is placed inside of the bowl. The cut nozzle is threaded into the hole outside the cap.
   A related technique, strawpedoing, is used for containers not easily punctured such as a glass bottles. A straw is inserted into the bottle and bent around the hole. When the bottle is tilted, the beverage quickly drains and is quickly consumed. The technique increases beverage delivery since the extra hole allows the liquid to leave while air enters simultaneously through the main hole. The bottleneck, created where air entering the container must travel through the same orifice as liquid leaving, is removed.
   Some levels have V grooves machined along their bases, enabling the level to sit on a round bar while remaining parallel with the bar's axis. They also have smaller cross levels to enable the second axes to be roughly checked or corrected and to ensure the primary axes' bubbles are at the tops of the vials.
   Separate plastic or composite fitments are also available for corrugated boxes.
  
  Section::::Plastic bottles.
  
  Many plastic containers have built in handles. Plastic shipping containers and storage tubs often have handles molded into them. Consumer blow molded containers often have integral handles or are shaped to facilitate grasping.
  
  Ssparate handles are sometimes added to a bottle, usually around the neck at the closure. Several methods have been developed.
  
  Section::::Bags.
  
  Many types of bags have handles to assist in carrying them.
  
  Section::::Multi-packs of beverage containers.
   Section::::Varieties.:Wall-mounted.
  
  Works the same as the lever variation, except that it is attached to the wall, to allow for simpler bottle-opening, which can be done with one hand. The bottle cap can fall into a bottle cap catcher mounted below the opener, or you can retrieve it after removal from the bottle. 
  
  A variant to this are similar types of openers mounted on older vending machines.
  
  Section::::Varieties.:Magnetic catch bottle opener.
  
  This is a bottle opener with a magnet to catch the lids. 
  
  Section::::Varieties.:Multi-opener.
   The world's first modern bottle cap, the crown cork, was invented by William Painter in 1890 in Baltimore.
  
  The screw cap using rust resistant aluminum was first used in prescription drug bottling in the 1920s. Molded urea based bottle caps were first introduced in the early 1900s.
  
  A history of accidents involving children opening household packaging and ingesting the contents led the US Congress to pass the Poison Prevention Packaging Act of 1970.
  
  Section::::The manufacture of closures.
   The "flip-top," "swing-top" or "Grolsch" style consists of a plastic or ceramic stopper held in place by a set of wires. Prior to the invention of the crown cork, this was the dominant method of sealing bottles that contained carbonated liquid.
  
  Section::::Types.:Screw cap.
  
  Screw on closures are the most common bottle caps. They are easy to apply by a wide variety of automated equipment, or they can be applied by hand.
   Hydrostatic loop
  
  A hydrostatic loop, though not often used in plumbing practice, is an arrangement of pipes formed into a vertical loop to prevent backflow of water within the plumbing potable water system. Since a siphon has a maximum height that it can work (about 33 feet), a hydrostatic loop is built higher than 33 feet. There are several ways to prevent siphonage and an undesirable backflow of the water in a plumbing system.
  
  BULLET::::- Vented loops
  
  Section::::See also.
  
  BULLET::::- backflow prevention
  
  BULLET::::- Pressure vacuum breaker
  
  BULLET::::- Double check valve
  
  BULLET::::- Chemigation valve
  
  BULLET::::- Reduced pressure zone device
   Fill line
  
  A fill line is a marking on drinkware indicating the volume of liquid held by the glass. Many countries mandate fill lines on glasses used commercially as a consumer protection measure.
  
  Section::::European Union and Switzerland.
   Section::::Feature Based Rules.:Boss.
  
  Boss, a basic design element in plastics, is typically cylindrical and used as a mounting fixture, location point, reinforcement feature or spacer. Under service conditions, bosses are often subjected to loadings not encountered in other sections of a component. 
   The 'wine cask' was invented by Thomas Angove (1918–2010) of Angove's, a winemaker from Renmark, South Australia, and patented by the company on April 20, 1965. Polyethelene bladders of 1 gallon (4.5 litres) were put into corrugated boxes for sale to consumers. An original design required that the consumer cut the corner off the bladder inside the box, pour out the desired quantity of wine and then reseal it with a special peg.
   A wide variety of convenience dispensing features can be built into closures. Spray bottles and cans with aerosol spray (valves, actuator) have special closure requirements. Pour spouts, triggers, sprayer cap, measuring attachments, sifting devices, etc. are common caps.
  
  Section::::Types of closures.:Spray Bottle.
  
  A spray bottle is a bottle that can dispense, squirt, spray or mist fluids. A common use for spray bottles is dispensing cool cleaners, cosmetics, and chemical specialties.
  
  Section::::Types of closures.:Child-resistant.
   There are several different types of commonly used closure systems. For glass vials, options include screw vials (closed with a screw cap or dropper/pipette), lip vials (closed with a cork or plastic stopper) and crimp vials (closed with a rubber stopper and a metal cap). Plastic vials, which can be moulded in plastic, can have other closure systems, such as 'hinge caps' which snap shut when pressed. These are sometimes called flip-tops or snap caps.
   An early-20th-century "bottom" (or seabed) drift bottle design by George Parker Bidder III involved weighting a bottle with a long copper wire that causes it to sink until the wire trails upon the sea bottom, at which time the bottle tends to remain a few inches above the bottom to be moved by the bottom current. A mushroom-shaped seabed drifter design has also been used. Seabed drifters are designed to be scooped up by a trawler or wash up on shore. Water pressure pressing on the cork or other closure was thought to keep a bottle better sealed; some designs included a wooden stick to stop the cork from imploding. Vessels of less scientific designs have survived for extended periods, including a baby food bottle a ginger beer bottle, and a 7-Up bottle.
   The application torque of closures, however, must be controlled in order for the closures to perform properly in the field. Closures must be applied tight enough to maintain a seal and to resist closure back-off, but must not be applied so tightly that the end user cannot remove the closure. They are often found on top of beers, such as Coors or Bud Light.
   Many small tire pumps come with a mounting bracket intended to be mounted alongside a bottle cage.
  
  The Trek Soho 3.0 comes with a stainless steel coffee mug designed to fit in the bottle cage mounted on the front side of the seat tube.
  
  In addition to the fairly standard cycling water bottle, cages have been produced to hold commercial 1 liter and 1.5 liter water bottles.
  
  Section::::History.
   The Young Grab, or the Young Modified Van Veen Grab Sampler is an instrument to sample sediment in the ocean. It is a modified version of the Van Veen grab sampler, with a clamshell bucket made out of stainless steel mounted to a supporting frame. The sampling area extracted with this instrument can vary depending on its size. With the modifications this version of the Van Veen grab sampler is heavier than the traditional version. The frame allows for better stability and level sampling. Weights can be attached to the frame to ensure the bucket grabs sufficient sediment, or skids to ensure the gear does not sink too deep in soft sediments.
   The use of empty vessels in construction dates back at least to ancient Rome, where many structures used empty amphorae embedded in concrete. This was not done for aesthetic reasons, but to lighten the load of upper levels of structures, and also to reduce concrete usage. This technique was used for example in the Circus of Maxentius.
   A variant of the Babcock bottle has a glass tube parallel to the neck, that crosses the wall of the body and ends just above its bottom. It allows the addition of water without disturbing the layer of fat as it rises into the graduated neck. In this variant, the flaring is on the auxiliary tube instead of on the neck. 
   To use a Vermaport correctly, a customer should position the front end of the shopping cart through the swing-open double doors at the foot of the device and give a push until the cart is engaged by the drive chain. There should be a slight tug if this is done correctly. Once the cart is engaged, the customer boards the adjacent escalator, which travels in parallel with the Vermaport, to the top of the run. Once there, he or she can stand just to the left of the exit doors to wait for the cart to be pushed through.
   Historically, vla (a popular dairy product with the consistency similar to custard or yoghurt) was sold in long glass bottles. Vla was frequently delivered by milkmen in bottles similar to the long, tapered-neck milk bottles used in many places in the world. However, while the use of the milk bottle streamlined production and distribution practices, the shape of the container made it hard to extract the last bits with spoons, spatulas, or other kitchen utensils. The Dutch answer was the bottle scraper which was perfectly suited to answer this problem.
   Section::::Closure lining materials.:Polyseal cone liners.
  
  Molded in Low-Density Polyethylene, Polyseal cone liners form to the inside of the bottleneck providing a leakproof seal which guards against back-off and product evaporation. Excellent for use with acid products and essential oils, these closures are recommended for use on glass bottles only.
  
  Section::::Closure lining materials.:Linerless designs – land seal (crab’s claw).
   BULLET::::- Funnel type. These bottle traps are made by cutting off the neck of the bottle as well as the complete tapering part of the top. The neck and cap are discarded. For catching wasps only the cap is removed, while leaving the neck in place. The tapering part is placed upside down on top of the rest of the bottle, thereby effectively forming a funnel. This funnel is then fixed to the bottle by piercing both bottle and funnel at two opposing sides. A wire fitted through these holes ensures the funnel solidly fits on the bottle, while the trap can easily be opened when required. After putting the bait in the bottle the trap is placed at the desired location.
   Typically, sewage flow enters at a high level and flows through the primary settlement tank. The supernatant from the tank flows into a dosing device, often a tipping bucket which delivers flow to the arms of the filter. The flush of water flows through the arms and exits through a series of holes pointing at an angle downwards. This propels the arms around distributing the liquid evenly over the surface of the filter media.
  
  Most are uncovered (unlike the accompanying diagram) and are freely ventilated to the atmosphere.
   Generally once he hits that range on his weight indicator, he waits while the jars open to the less restricted point, whereupon the sinker bar travels upwards rapidly, providing an upwards hit on the downhole tools. The jars can then be 'reset' by lowering the line until the weight of the sinker bar closes, or pushes the inner mandrel of the hydraulic jars back to the starting position. Because the hydraulic jars are designed to provide a wait time to allow the operator to get up to the desired line tension, they can provide a very effective upwards hit.
  