Basic Definition regarding to Dispensing Process

The word dispense comes from the old French word “dispenser” meaning “give out”. To dispense is to give or deal out something, especially in a specific portion or amount.

is a device that monitors and physically alters the operating conditions of a given dynamical system. Historically a controller employs mechanical, hydraulic, pneumatic or electronic techniques, often in combination. In the last couple of years microprocessors and computers took over. Typical applications of controllers are to maintain settings for temperature, pressure, flow or speed.

A subsystem ỏ independent device that determines and maintains the operating parameters of a system, usually within certain prescribed or preset limits. A common example is the pressure regulator, which enables a system to maintain constantly the pressure to which it is adjusted.

Simple adjustable pressure regulator

To clear off, or eliminate, unwanted physical matter from an unclear container or space, i.e., to purge the air from a water pipe or to purge the air from within a dispensing system. A good example is purging to eliminate air bubble, which may enter the dispensing system is very important to ensure quality in dispensing applications. To purge a two-component system also helps to avoid premature curing.

A device that measures and records the quantity, degree, or rate of something that is used. An example is the meter in a taxi that measures the distance traveled or the amount of time spent traveling and shows the fare to be paid. A dispensing meter in combination with a controller may measure and control the volume, flow and pressure used in applying adhesive material.

When talking about the capability of dispensing technique to enhance process quality, the terms accuracy and precision are often used. Although many people think they are the same, this is actually not the case. Accuracy is how close a measured value is to the actual intended value. Precision is how close the measured values are to each other.

²Pressure is the amount of force applied perpendicular to the surface of an object per unit area. Various units can be used, but the International System of Units (SI) – Pasca (Pa) has the following standard:

Pressure: P = F/A

with P = Pressure; F = normal force in [N = kg/s²] Newton; A = area of the surface in contact in square meter m².

Viscosity is the resistance of a substance to flow. It is related to the concept of shear force and can be understood as the effect of different layers of the fluid exerting shearing force on each other, or on other surfaces, as they move against each other. From an adhesive bonding perspective, viscosity is important due to its influence on the quality of an application bead.

Volume is the amount of three-dimensional space enclosed by a certain boundary; for example, the space that a substance (solid, liquid, gas) or shape occupies or contains. It is possible to calculate volume using different formulate, depending on the shape of an object or room.

In physics and engineer, particularly in the area of fluid dynamics and hydrometry, the volumetric flow rate is the volume of fluid which passes per unit time. It is represented by the symbol Q. The SI unit is m³/s (cubic meters per second).

Q = v.a

v = flow velocity of the substance elements; A = cross-sectional vector area/surface; Volume flow rate with common symbols are V, Q; SI unit: m³/s.

The density or volumetric mass density of a substance is its mass per unit volume. This varies with temperature and pressure. The variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases its volume and thus its density.

ρ=m/V (kg/m³)

ρ = density; m = mass; V = volume