Dispensing pumps

Toothpastes are packaged in flexible tubes, other flexible containers, and mechanically operated pump dispensers. They are usually extmded as cylindrical ribbons of a cohesive, smooth paste, approximately 2.54 cm in length and weighing approximately 1.5 g. New or modified dispensing devices are continually introduced to increase consumer interest. 

J. P. Bare, B. Johl, and T. A. Lemke, Comparison of Vacuum-Pressure vs. Pump Dispense Engines for CMP Slurry Distribution, Proceedings of SEMlCONtWesl Contamination in Liquid Chemical Distribution Systems Workshop (July, 1998). 

With aerosol cleaning products, a quick spray and a blow-dry with compressed air, or a wipe with a dry rag or towel is all that is required to remove the unwanted soil. Another benefit of spraying is the motive force of the spray, which assists in soil removal. Because of the tendency for aerosol products to finely atomize the cleaning solvent and increase air emissions, some air-quahty agencies are mandating the use of low-vapor-pressure solvents in hand-pump dispensers. This action reduces solvent loss to the atmosphere and increases the amount of waste solvent, which must be collected and stored for subsequent recycling or disposal. 

Thixotropy provides a shear thinning effect that is, viscosity decreases as the shear rate increases, and vice versa. This not only allows easy pumping, dispensing, and mixing of the adhesive, but also provides sag resistance once the adhesive is applied. The thixotropic fillers work by forming a temporary structure in the mixture, which can be broken down at high rates of shear. This structure is generally the result of van der Waals forces between molecules. 

Bare J, Johl B, Lemke T. Comparison of vacuum-pressure vs. pump dispense engines for CMP slurry distributionProceedings of SEMICON/West Contamination in Liquid Chemical Distribution Systems Workshop 1998 July. 

Nasal drug delivery devices can be divided into multidose and unit-dose/bi-dose systems. Multidose systems consist of a container mounted with a mechanical pump dispenser that is designed to deliver multiple doses from one container (Fig. 1). The various requirements of the customer and of the formulation are respected in the design and performance of the delivery systems. Unit-dose and bi-dose systems are becoming increasingly attractive to the pharmaceutical industry. In particular, therapies that require precise performance in their delivery system employ these single/ dual-use disposable systems. 

Cartesian Dispensing SynQuad Hummingbird High-speed microsolenoid valve with a high-resolution syringe pump dispense system. Delivery volumes from 20 nL to pi. www.cartesiantech.com... 

Formulations for nasal application need to be sterile and free of cilliotoxic substances. Solutions may be applied via pump dispensers. Nasal powders on the other side require special application systems like, for example, the Jetilizer [25]. This system follows a twin construction pattern with two nozzles. The capsule containing the particle-based formulation is opened by needles. A pump-activated air stream aerosolizes the powder in an equilibrium chamber. After passing a conical tube, the powder is applied with a high deposition rate to the absorption area within the nose. 

To illustrate the hyphenation between FIA and HPLC, a system for food additives (acesulfame-k, saccharin, caffeine, benzoic acid and sorbic acid) determination [40] is shown in Figure 3.14. The system includes a dialysis cell in order to eliminate the sample matrix. Thus, a peristaltic pump dispenses the sample, which is loaded into a holding coil of an injection valve (IVl) and later injected into the donor stream. Both, donor and acceptor streams are also propelled by the peristaltic pump. Once the dialysis has been performed, analytes are loaded into a holding coil of a second injection valve (IV2). At this point, the sample passes to the HPLC system. The sample is injected into a mobile phase stream dispensed by the HPLC pump. So, the pretreated sample passes through the precolumn and column, and the analytes are separated and detected. Thus, the treatment, separation and detection steps are carried out in an efficient and high automated way. 

Time-pressure pump dispensing is a method to deposit adhesive or solder paste by applying a pressure pulse for a specific time duration on a reservoir of material (see Rg. 40.17). A precisely controlled quantity of adhesive or solder paste emerges from the selected orifice size, which is deposited on the circuit board. Often, the material comes prepackaged in a syringe that is inserted into the machine. 

FIGURE 40.17 Time-pressure pump dispensing technique (a) The dispenser is positioned at the circuit board site (b) the dispenser is lowered to near the surface at which time, a pulse of air pushes the piston a distance Ax to dispense a set quantity of adhesive (c) the dispenser is raised from the site, leaving the adhesive deposit. 

As with all dispensing techniques, the flow properties of the adhesive or solder paste are important factors that determine the consistency of the deposit between the different sites. Shelf-life requirements should be strictly followed, particularly those pertaining to time allowed for the material to be present in the dispenser due to rapid degradation when open to the factory floor environment. The desired viscosity for pump dispensing through a nozzle is 100 to 400 kcps. 

Archimedes screw pump dispensing utilizes an Archimedes screw to push the adhesive or solder paste out of a nozzle (see Fig. 40.18.) The speed and duration of a turn, as well as the size of the opening, determine the quantity of adhesive or paste deposited on the site. As in the case of the time-pressure technique, different deposit quantities can be realized by multiple spindle (heads) or a computer program that alters the screw speed or turn duration to change the amount of material dispensed from the same orifice. All other considerations with respect to the roles of adhesive or solder paste viscosity and shelf-life also apply to this technique. 

Positive displacement pump dispensing uses a piston, rather than an air pressure pulse, to control the deposit quantity. This technique is used primarily to dispense adhesive (see Fig. 40.19). First, the nozzle is placed in a bath of adhesive, in which it retracts to draw a... 

FIGURE 40.19 Positive displacement pump dispensing technique (a) The dispenser is brought to the adhesive reservoir (b) the nozzle is immersed into the adhesive and the piston withdrawn a distance Ax, resulting in a set quantity of material being pulled into the cylinder (c) the dispenser is brought to just above the circuit board surface so that a reverse displacement of the piston pushes out a quantity of adhesive (d) the dispenser is lifted from the circuit board. 

The most informative study to date was published by Brannan and DiUe in 1990 (17). The study involved the use of an unpreserved shampoo and a skin lotion product that were verified using a standard PET closure. The two products were packaged in identical bottles. Their data proved that closures and dispensers vary in their ability to resist contamination. The pump dispenser was the most contamination-resistant delivery system evaluated for lotions. The flip cap dispenser appeared to be the most protective for shampoos. Other studies showed that pump top closures are more protective in preventing... 

Several of our Olay Skin Care products now utilise new consumer-preferred pump dispenser originally developed by a European packaging products company. P G led a collaborative improvement process to make the original pumps more effective prior to their launch in Olay s North American markets. 

Uses Surfactant, moisturizer, and softener for styling mousses, facial foaming cleansers, pump-dispensed oil sheens for ethnic hair care... 

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