Flow sensor

Transfer path is Verify open and clear transfer path before initi-blocked due to ating transfer closed valve, blind, Utilize pressure and flow sensors etc. Pressure is built up in system and leaks in piping occur. CCPS G-29... 

Ignition controls shall include upstream (in flare header prior to knockout drum) dual flow sensing equipment which shall start the automatic flare purge, pilot ignition and the flare ignition cycle. N P Refinery will be responsible for the wiring between the flow sensors and the ignition control panel. 

Flow High Flow Sensor Flow Safety High 0 ... 

Zougagh, M., Valcarcel, M., and Rios, A., Automatic selective determination of caffeine in coffee and tea samples by using a supported liquid membrane-modified piezoelectric flow sensor with molecularly imprinted polymer. Trends Anal. Chem., 23, 399, 2004. 

The flowing sensor medium as an integral part of remote detection naturally leads to the study of flow through porous media [40, 41]. In addition to carrying the... 

Molecular rotors are fluorophores characteristic for having a fluorescent quantum yield that strongly depends on the viscosity of the solvent [50], This property relies on the ability to resume a twisted conformation in the excited state (twisted intramolecular charge transfer or TICT state) that has a lower energy than the planar conformation. The de-excitation from the twisted conformation happens via a non-radiative pathway. Since the formation of the TICT state is favored in viscous solvents or at low temperature, the probability of fluorescence emission is reduced under those conditions [51]. Molecular rotors have been used as viscosity and flow sensors for biological applications [52], Modifications on their structure have introduced new reactivity that might increase the diversity of their use in the future [53] (see Fig. 6.7). 

Flow sensors were also used coupled with microdialysis probe [236], providing several advantages the reaction took place in few minutes allowing continuous analysis the sensitivity was in the order of pmoles the microdialysis probe allowed biological specimens to be drawn without proteins or macromolecules. This technique can be extended to the analysis of analytes that need to be detected continuously such as during therapy monitoring, or in emergency care units. 

Air mass flow sensors can be used in fans and vacuum cleaners. 

Many commercial split flow capillary LC systems incorporate a nano flow sensor mounted online to the capillary channel. The split flow system can be easily modified from a conventional system and performs satisfactorily for capillary LC applications. However, the split flow system may require thermal control and the LC solvent requires continuous degassing. In addition, the system may not work reliably at a high flow split ratios and at pressures above 6000 psi due to technical limitations of the fused silica thermal conductivity flow sensor. The split flow system based on conventional check valve design may not be compatible with splitless nano LC applications. The conventional ball-and-seat check valve is not capable of delivering nano flow rates and is not reliable for 7/24 operation at low flow. 

The exhaust duct of each ventilated containment cabinet must be fitted with an adjustable low flow sensor. Audible and visible alarms must be located near the cabinet, and the silence switch should energize an indicator at the status board. These are local alarms which should not automatically trigger a call for emergency response personnel. 

Other instruments include the Calvet microcalorimeters [113], some of which can also run in the scanning mode as a DSC. These are available commercially from SETARAM. The calorimeters exist in several configurations. Each consists of sample and reference vessels placed in an isothermally controlled and insulated block. The side walls are in intimate contact with heat-flow sensors. Typical volumes of sample/reference vessels are 0.1 to 100 cm3, The instruments can be operated from below ambient temperatures up to 300°C (some high temperature instruments can operate up to 1000°C). The sensitivity of these instruments is better than 1 pW, which translates to a detection limit of 1 x 10-3 W/kg with a sample mass of 1 g. 

Vapor-flow sensor and vapor-sampling ports located near the vapor extraction well heads. 

When a flow sensor is installed for accurate accounting measurements of the absolute flow rate, many precautions must be taken, such as providing a long section of straight pipe before the orifice plate. For control purposes, however, one may not need to know the absolute value of the flow but only the changes in flow rate. Therefore pressure drops over pieces of equipment, around elbows or over sections of pipe can sometimes be used to get a rough indication of flow rate changes. 

If orifice plates are used as flow sensors, the signals from the differential-pressure transmitters are reaUy the squares of the flow rates. Some instrument engineers prefer to put in square-root extractors and convert everything to linear flow signals. 

Figure 16.4 Experimental set-up of an on-line FIA system ( ) bioreactor, (2) glycerol standard solution, (3) water for dilution, (4) buffer solution containing NAD, (5) buffer solution containing ferricyanide, (6-1) switch valve, (6-2 and 6-3) injection valves, (7-1 and 7-2) peristaltic pumps, (8) mixing chamber, (9) degasser, (10) flow sensor containing biosensor, and (11) waste. (Reprinted from Sefcovicova et al/ with permission from Elsevier.)...

The electrochemical flow sensor for in situ monitoring of total cadmium concentration in the presence of EDTA and nitrilotriacetic acid (NTA) ligands has been described [379]. 

Another recent development is the advent of pulse amperometry in which the potential is repeatedly pulsed between two (or more) values. The current at each potential or the difference between these two currents ( differential pulse amperometry ) can be used to advantage for a number of applications. Similar advantages can result from the simultaneous monitoring of two (or more) electrodes poised at different potentials. In the remainder of this chapter it will be shown how the basic concepts of amperometry can be applied to various liquid chromatography detectors. There is not one universal electrochemical detector for liquid chromatography, but, rather, a family of different devices that have advantages for particular applications. Electrochemical detection has also been employed with flow injection analysis (where there is no chromatographic separation), in capillary electrophoresis, and in continuous-flow sensors. 

Other sensors which are described in Volume 1 (Sections 6.3.7-6.3.9) are the variable area meter, the notch or weir, the hot wire anemometer, the electromagnetic flowmeter and the positive displacement meter. Some of these flowmeters are relatively less suitable for producing signals which can be transmitted to the control room for display (e.g. weir, rotameter) and others are used in more specialist or limited applications (e.g. magnetic flowmeter, hot wire anemometer). The major characteristics of different types of flow sensor are summarised in Table 6.1. Brief descriptions follow of the principles underlying the more important types of flowmeter not described in Volume 1. In many instances such flow sensors are taking the place of those more traditional meters which rely upon pressure drop measurement. This is for reasons of versatility, energy conservation and convenience. 

The general conclusion to be drawn from these studies is that the use of small pyroelectric elements as heat flow sensors in chemical investigations holds some promise. The early stage of the studies makes it difficult to assess the extent of their utility. New adsorber materials are an essential requirement if these structures are to fulfil their promise. 

Microfluidics control thanks to integrated electrochemical flow sensors... 

Fj, F2, Brooks Instruments Model No. 5812 mass flow sensor and... 

Paraoxon Vegetables HPLC with chemiluminescence- -based flow sensor [113]... 

Without being itself a screening device, the reactor of Jensen et al. [6, 42, 43] also has to be mentioned because they opened up a completely new field in catalysis by combining MEMS (micro-electro-mechanical systems) technology with a chip-based catalytic reactor (Fig. 4.10). A mixing-tee was equipped with heaters and temperature and flow sensors, thus giving on-stream information about the reaction conditions. 

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