Units temperature, 16 time

Flow, defined as volume per unit of time at specified temperature and pressure conditions, is generally measured By positive-displacement or rate meters. The term positive-displacement meter apphes to a device in which the flow is divided into isolated measured volumes when the number of fillings of these volumes is counted in some man-... 

Accuracy and repeatability of temperature/time/velocity/pressure controls of injection unit, accuracy and repeatability of clamping force, flatness and parallelism of platens, even distribution of clamping on all tie rods, repeatability of controlling pressure and temperature of oil, oil temperature variation minimized, no oil contamination (by the time you see oil contamination damage to the hydraulic system could have already occurred), machine properly leveled. 

The rates of each of the environmentally important chemical processes are influenced by numerous parameters, but most processes are described mathematically by only one or two variables. For example, the rate of biodegradation varies for each chemical with time, microbial population characteristics, temperature, pH, and other reactants. In modeling efforts, however, this rate can be approximated by a first-order rate constant (in units of time). 

Time is one of the so-called base units within the SI system, and so is length. Whereas volume can be expressed in terms of a length (for example, a cube has a volume l3 and side of area l2), we cannot define length in terms of something simpler. Similarly, whereas a velocity is a length per unit time, we cannot express time in terms of something simpler. In fact, just as compounds are made up of elements, so all scientific units are made up from seven base units length, time, mass, temperature, current, amount of material and luminous intensity. 

There are seven base SI units length, time, mass, temperature, current, luminous intensity and amount of material. 

Heat flux is defined as heat input per unit of time per square unit of inside tube surface. A low heat flux provides extra catalyst volume and lower tubewall temperatures. This increases the reforming reaction conversion and increases tube life. A high heat flux reverses these effect, but reduces the number of tubes. The flux is highest at the zone of maximum heat release and then drops to a relatively low value at the tube outlet. 

The rate of heat production dQ ldt is the quantity of heat that is produced per unit of time. This rate is proportional to the reaction rate the latter is a function of the concentrations and the temperature. 

Read excerpts 3N and 30. Pay particular attention to (1) the form of numbers (numerical or word form) and (2) the formatting of units for time and measure (e.g., temperature, concentration, volume, area, and length). What do you notice ... 

Two main types of viscometers are suitable for the determination of the viscosity of a polymer melt The rotation viscometer (Couette viscometer, cone-plate viscometer) and the capillary viscometer or capillary extrusiometer. The latter are especially suitable for laboratory use since they are relatively easy to handle and are also applicable in the case of high shear rates. With the capillary extrusiometer the measure of fluidity is not expressed in terms of the melt viscosity q but as the amount of material extruded in a given time (10 min). The amount of ex-trudate per unit of time is called the melt index or melt flow index i (MFI). It is also necessary to specify the temperature and the shearing stress or load. Thus MFI/2 (190 °C)=9.2 g/10 min means that at 190 °C and 2 kg load, 9.2 g of poly-... 

The term flow volume designates the volume of the gas which flow/s through a piping element within a unit of time, at the pressure and temperature prevailing at the particular moment. Here one must realize that, although volumetric flow may be identical, the number of molecules moved may differ, depending on the pressure and temperature. 

The flow rate of fluids is a critical variable in most chemical engineering applications, ranging from flows in the process indnstries to environmental flows and to flows within the hnman body. Flow is defined as mass flow or volume flow per unit of time at specified temperatnre and pressure conditions for a given flnid. This snbsection deals with the techniques of measuring pressure, temperature, velocities, and flow rates of flowing fluids. For more detailed discussion of these variables, consult Sec. 8. Section 8 introduces methods of measuring flow rate, temperature, and pressure. This subsection bnilds on the coverage in Sec. 8 with emphasis on measurement of the flow of fluids. 

Though Eqs. (3.41) and (3.42) are somewhat cumbersome, they describe the rate at which nuclei form as a function of temperature. Note that in both equations, Hs and no have dimensions of number per unit volume, and vq has units of time ... 

In Eqn. 5.3-1, rj is the effectiveness factor of the catalyst with respect to the dissolved gaseous reactant and the temperature of the outer surface. The rate of reaction within the catalyst pores is comprised in rj. R is the reaction rate expressed in moles of gaseous reactant, A, per unit of bubble-free liquid, per unit of time. Reaction is irreversible. In equation (1) it has not been assumed that the gas is pure gas A, its concentration in the bubbles being Cg. Also, Henry s law for the gas is assumed and written as in Eqn. 5,3-4. Using Henry s law, Eqn. 5.3-4, the intermediate concentrations (Cs, CL) can be eliminated using the above system of equations. This provides an expression of the global rate in terms of an apparent constant, ko, that contains the various kinetic and mass transfer steps. Therefore, the observed rate can be written as ... 

Mutarotation has been shown to be a first-order reaction, the velocity constant being independent of reaction time and concentration of reactants. The rate of mutarotation increases 2.8 times with a 10°C rise in temperature. By applying the law of mass action, equations have been developed to measure the rate of the reversible reaction between the a and (3 forms of lactose. If a dilute lactose solution at constant temperature contain a moles of a and b moles of /3, then the amount of (3 formed (x) per unit of time is... 

The linear heat up rate is important in temperature-programmed units. Temperature rates from about 0.25 to at least 10°C/min should be available. The temperature steps at the bottom end should be small for capillary columns. Program rates in excess of 10°C/min are rarely useful (33). The penalty of large increases in temperature for small decreases in retention times does not warrant program rates above about 10°C/min. 

The measurement of pre-vulcanisation properties is given in ISO 289-238. This is essentially a matter of running a test on a fully compounded material (including curatives) as in ISO 289-1 until the viscosity reaches a specified number of units above the minimum (usually 5 units). The time to this point is designated as the scorch or pre-vulcanization time. The temperature of test is chosen to suit the process in question. 

Thermal conductivity may be defined as the quantity of heat passing per unit time normally through unit area of a material of unit thickness for unit temperature difference between the faces. In the steady state, i.e. when the temperature at any point in the material is constant with time, conductivity is the parameter which controls heat transfer. It is then related to the heat flow and temperature gradient by ... 

The surface heat transfer coefficient can be defined as the quantity of heat flowing per unit time normal to the surface across unit area of the interface between two materials with unit temperature difference across the... 

A theoretical model of the low-temperature decay of etr in MTHF discovered in ref. 30 was suggested in ref. 31. According to this model, the disappearance of et in y-irradiated MTHF at 77 K is due to electron tunneling from a trap to a hole centre. The form of the potential barrier for electron tunneling used in ref. 31 to analyze the curves of the decay of etr is represented schematically in Fig. 9(a). To evaluate the probability of tunneling per unit of time, the Gamow formula... 

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