Bottle threads

Bottle-top dispensers, often called Repipets , are quite popular. These are devices that fit on the top of reagent bottles threaded to receive screw caps. The dispensers themselves have screw caps that screw onto the bottles. The caps, however, are fitted with a hand pump with a plunger that draws liquid from the bottle in the upstroke and then dispenses a calibrated volume on the downstroke through a glass tip. Such devices are convenient and help prevent contamination of the reagent from the various pipets that the analyst might use for a transfer. 

Injection blow molding. Injection blow molding, depicted in Fig. 3.60 [25], begins by injection molding the parison onto a core and into a mold with finished bottle threads. The formed parison has a thickness distribution that leads to reduced thickness variations throughout the container. 

Prior to sampling, every bottle (or sample container) should be rinsed twice with the water to be sampled. During the rinsing process, bottle caps should be put on loosely to ensure adequate rinsing of the cap, liner, and bottle threads. If replicate samples are taken, every set of bottles should be rinsed twice and then filled, one set after the other (i.e., sequentially). 

When the mold is opened, the part should be easily removable. Cavities are made with a slight taper to reduce frictional drag of the part on the mold. The half of the mold attached to the movable platen is equipped with ejector pins, which push the part out of the cavity while the mold is being opened. When the mold is closed, the pins are flush with the cavity surface. Release agents or lubricants facilitate ejection and shorten the mol ding cycle. Some complex parts require that the mold open in several directions in addition to the direction of the platen movement. For a threaded part, eg, a bottle cap, part of the mold must be rotated to remove the article from the mold. 

Internal plastic thread The strength of plastic threads is limited, and when molded in a product involving either an unscrewing device or a rounded shape of thread similar to bottle-cap threads, they can be stripped from the core. Screw threads, when needed, should be of the coarse type and have the outside of the thread rounded so as not to present a sharp V to the plastic that can produce a notch effect. 

Bottle caps made from different plastics are extensively used. Some closures are of the simple cork snap type design, but most are of the screw type. Strong, accurate threads can be molded, which represent undercuts. Simple designs should be used when permitted, such as wide-pitch threads. The thread should be designed to start about 1 /32 in. (0.08 cm) from the end of the face perpendicular to the axis of the thread. It is usually practical to mold up to 32 threads per in. more than this number can give certain molders trouble. 

The dry material is readily ignited, bums very rapidly and is moderately sensitive to heat, shock, friction or contact with combustible materials. When heated above its m.p. (103-105°C), instantaneous and explosive decomposition occurs without flame, but the decomposition products are flammable. If under confinement (or in large bulk), decomposition may be violently explosive [1], An explosion which occurred when a screw-capped bottle of the peroxide was opened was attributed to friction initiating a mixture of peroxide and organic dust in the cap threads [2], Waxed paper tubs are recommended to store this and other sensitive solids [3], Crystallisation of the peroxide from hot chloroform solution involves a high risk of explosion. Precipitation from cold chloroform solution by methanol is safer [4], Water- or plasticiser-containing pastes of dibenzoyl peroxide are much safer for industrial use. 

An accident investigation identified the cause of the accident to be the rapid decomposition of peroxides, which formed in the ether while the bottle sat in storage. It is hypothesized that some of the peroxides crystallized in the threads of the cap and exploded when the cap was turned. 

Fig. 7.11 Wake configurations for drops in water (highly purified systems), reproduced from Winnikow and Chao (W8) with permission, (a) nonoscillating nitrobenzene drop = 0.280 cm, Re = 515 steady thread-like laminar wake (b) nonoscillating m-nitrotoluene drop 4 = 0.380 cm. Re = 688 steady thread accompanied by attached toroidal vortex wake (c) oscillating nitrobenzene drop 4 = 0.380 cm. Re = 686 central thread plus axisymmetric outer vortex sheet rolled inward to give inverted bottle shape of wake (d) oscillating nitrobenzene drop = 0.454 cm. Re = 775 vortex sheet in c has broken down to form vortex rings (e) oscillating nitrobenzene drop d = 0.490 cm. Re = 804 vortex rings in d now shed asymmetrically and the drop exhibits a rocking motion.

Other plastic bottles can be blown on a sterile bottle blower and be supplied closed (i.e. material seals the bottle above the screw thread or neck). The bottles... 

Metal roll-on (RO) closures are used mainly on glass bottles, where the neck finish tolerance makes it very difficult to produce a pre-threaded cap that will... 

The retained TE ring is normally used for one-trip bottles. If the design intends the consumer to drink directly from the bottle, then importance will be placed on the height of the neck finish from die TE bead to ensure that the consumer s lips do not touch the sharp edge of the TE ring. If the product is carbonated and needs to be in-pack pasteurized, then consideration will have to be given to the thread form on the bottle (usually glass) neck. 

Fig. 1.10. Transfer of air-sensitive liquids from metal cylinders, (a) A three-way metal stopcock constructed for use with syringes may be modified by the addition of a threaded fitting so that it mates with a lecture bottle. The side inlet is used to purge the apparatus initially and to blow liquid out of the syringe needle at the completion of the transfer. The cylinder is put under a low pressure of inert gas before the transfer is begun, (b) Sometimes air-sensitive liquids are sold in siphon-type cylinders, and the liquid from such a cylinder can be dispensed as shown here. As with the previous example, inert gas is used to force the liquid out of the cylinder.

For even greater heat shock resistance and chemical durability, alumina (A1203) can be used instead of boron oxide. The resultant aluminosilicate glass has such resistance to heat shock that it can be used direcdy on the heating element of the kitchen stovetop. It is also used to make the special bottles used for liquid pharmaceutical prescriptions, and to produce the glass thread that is woven into fiberglass fabric. 

In a hood, 211 g. of powdered phosphorus(V) chloride (1.01 mols) is intimately mixed with 75 g. of powdered phosphorus ) sulfide (0.338 mol) in a 500-ml. beaker. This mixture is then transferred to the lecture bottle. Use of a 150-mm. short-stemmed funnel and a stirring rod facilitates this transfer and keeps the pipe threads clean. After treatment with pipe-joint compound, the pipe plug is screwed into place. (A satisfactory pipe-joint compound can be made by grinding litharge and glycerol together.)... 

Small bottles, 187 mL, are closed with crown caps or roll-on aluminum caps. For special customers such as airlines, these closures are used also on 750-mL bottles. The roll-on or ROPP closure is the more popular of the two. These are aluminum cups, 30 mm in diameter and 22 mm high, with an inner elastomer plastic seal. After the caps are placed on the bottle, rotating dies roll the aluminum over the threads of the bottle. Bottles for these caps have a specially designed thread finish. 

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