Sensing taps

Both matter-like (a) and geometry-like (kj) information must be dynamical constructs of primordial bits of information value and link dynamics must not just mimic one-another via a weak coupling, rather they must, in a sense, tap from the same informational source when it comes to their mutual creation and/or annihilation. 

The pressure-sensing tap must go all the way through the wall— metal skin and refractory. Flare the refractory opening into a cone so that crumbs of refractory and... 

The elevation of the pressure-sensing tap does not necessarily have to be at the elevation desired for the neutral pressure plane. The most desirable height for the zero pressure plane may be at a point that turns out to be bad for good measurement, for example, below the hearth, at a level where scale might plug the pressure tap, or in a place where liquid metal may splash into the tap. In such cases, a very workable solution is to locate the sensor tap at a convenient higher position and then adjust the controller s setpoint in accordance with the correction for the rise in pressure for the chosen higher elevation from table 6.2. (See example 6.2.)... 

In case of a major problem in meeting the 3% line loss criterion, a pilot-operated relief valve can be installed with a pressure sensing tapping taken from the protected equipment. With such an installahon, it is still required to reduce the inlet pressure drop as... 

Pitot Tubes. The fundamental design of a pitot tube is shown in Eigure 9a. The opening into the flow stream measures the total or stagnation pressure of the stream whereas a wall tap senses static pressure. The velocity at the tip opening, lA can be obtained by the Bernoulli equation ... 

Valve. seat Fails to block flow when closed. Possible leakage of SIS fluid into system and reduced operability. Need leakage taps on system to determine if there is leakage between series valves. Sense temperature of pipe. Inspection. 

In some situations, it makes good economic sense to tap the earth s heat as an energy source. One approach to utilizing this resource is illustrated in the sidebar on this page. 

The code used by the plumber for the bath taps is precisely opposite to the astronomer s rule of thumb. Between the artisan and the astronomer, Goethe chose the first. For him, and for all artists since the beginning of time, blue has been associated with what is spiritually cold. In his Theory of Colours Zur Farbenlehre, 1810), he wrote that blue expresses a purely empirical psychological impression of cold. Our own science places all sense perceptions such as sound, colour and heat firmly within the human sphere. Nothing outside the human being corresponds to these qualities. 

Local Static Pressure In a moving fluid, the local static pressure is equal to the pressure on a surface which moves with the fluid or to the normal pressure (for newtonian fluids) on a stationary surface which parallels the flow. The pressure on such a surface is measured by making a small hole perpendicular to the surface and connecting the opening to a pressure-sensing element (Fig. 10-8a). The hole is known as a piezometer opening or pressure tap. 

Solid-state sensors for anionic surfactants can be constructed by using polyaniline as sensing membrane [107,108], and by using polypyrrole as ion-to-electron transducer in combination with plasticized PYC as sensing membranes [53,66]. The sensors may be applied for the determination of dodecylsulfate in, e.g., mouth-washing solution and tap water [107], and for the determination of dodecylbenzenesulfonate in detergents [66,108]. Solid-state surfactant sensors allow a sample rate of 30 samples/h, when applied in flow-injection analysis [53]. 

A more economic solution is to replace the valves with POSRVs with remote pressure sensing. Instead of having a pressure pick-up to the pilot at the inlet of the main valve, pressure can be measured on the system, bypassing the inlet piping and its pressure losses. This solution is also easily field convertible if the snap-action pilot has integral pressure sensing. A typical remote sense point could be a tee into a gauge tap. 

The inductance-type transducer consists of three parts a coil, a movable magnetic core, and a pressure sensing element. The element is attached to the core, and, as pressure varies, the element causes the core to move inside the coil. An AC voltage is applied to the coil, and, as the core moves, the inductance of the coil changes. The current through the coil will increase as the inductance decreases. For increased sensitivity, the coil can be separated into two coils by utilizing a center tap, as shown in Figure 7. As the core moves within the coils, the inductance of one coil will increase, while the other will decrease. 

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