Digital meter

The luminous intensity for various types of illuminating and tracer flares is measured by using a photometer which mainly consists of two parts-optical part (mainly photovoltaic detector) and electronic part (consisting of amplifier, digital meter, computer with interface card and printer). The experimental set-up is shown in Figure 5.5. 

Patients should be instructed about the correct orientation of digital meters. 

Alternating current indicators are almost exclusively of the moving iron vane type because of their wide range and low sensitivity to frequency variations (less than the electrodynamic type). For current measurement above the range of moving iron vane and digital meters, a current transformer is the simplest and cheapest solution. When inserted in the circuit, it provides the proper ratio between the meter range and the measured current. 

Flow Monitoring Digital meter, turbine type with totalizer... 

The pH of the solution was measured with an Orion Research model 601A digital meter and a Markson model 788 combination electrode. 

Several types of readout devices are found in modern instruments. Some of those devices include the D Arsonval meter, digital meters, recorders, cathode-ray lubcs, LCD panels, and computer displays. 

Figure 9- 1.1b is a schematic of a typical double-beam-intime instrument. The beam from the hollow-cathode source is split by a mirrored chopper, one half passing through Ihe tlame and the other half around it. The two beams are then recombined by a half-silvered mirror and passed into a Czerny-Turner grating monochromator a photomultiplier tube serves as Ihe transducer. The output from the latter is the input to a lock-in amplifier that is synchronized with the chopper drive. The ratio between the reference and sample signal is then amplified and fed to the readout, which may be a digital meter or a computer. 

The first thermocouple in Figure 1 was coimected to the temperature controller (Part No. CN4800, Omega Engineering, Stanford, CT) which regulated the oven temperature while the other thermocouples were connected to a digital meter to obtain an accurate reading of the water temperature, both before and after the extraction cell. 

Since most electrochemical measurements relating to corrosion of metals are satisfied with a sensitivity of 1 jiV or 1 xA, modern instrumentation usually employs electronic operational amplifiers where the noise limits control the range of measurements. The function of the operational amplifier is to amplify the potential (Vg) applied at the input so that it can be displayed on a low impedance analogue or digital meter (V ) as shown in Fig. 1.1. The output potential of the operational amplifier is proportional to the source potential and is required to have sufficient input impedance to avoid polarisation of the potential source. 

FlowMonitonng Digital meter, turbine pe with to izer... 

The solutes chosen were (S) and (R) 4-benzyl-2-oxazolidinone. The apparatus consisted of an LC pump, a 1 pi internal loop sample valve and the column was situated in a thermostatically controlled oven. The oven could be operated at temperatures between 5°C and 85°C with a precision of 0.2°C. The mobile phase was passed through a preheater, consisting of 1 m length of coiled stainless steel tube, 0.010 in. ID., situated in the thermostat, between the sample valve and the column. The column outlet was connected directly to a UV detector operating at 220 nm. The eluent from the detector was passed to a 50 ml Grade A burette and the retention volumes were measured directly in ml of mobile phase. The burette was read with an accuracy of 0.02 ml. The output of the detector was displayed on a digital meter and an electronic recorder/integrator. 

The experimental procedure was as follows. The burette was read, the sample injected and the pump started. The detector output was observed by the digital meter and when a peak emerged the pump was shut off at the peak maximum. The system was allowed half a minute to reach equilibrium and the burette read again. The difference between the readings was taken as the retention volume being measured. The dead volume was taken as the elution volume of ethanol, the sample solvent. 

Station feed positions are Indicated on the panel by both bar and digital meters to provide accurate displacement readings. 

OFA sample at room temperature. H2S digital meter, attached at the exit, is used to measirre H2S concentration as fnnction of time. Desorption was performed in a similar way by passing nitrogen to the colrnnn and the resnlting H2S concentration data were recorded. 

Digital meters provide the same functions as analogue meters but they display the indicated value using a seven-segment LED to give a numerical value of the measurement,... 

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