Rate Meters

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-... 

These meters are suitable for low-pressure applications (<75mbar) and low flow rates. Meters rated at up to... 

Integration. A detector that yields discrete pulses can be used as an instantaneous detector if the pulses can be averaged to form a continuous electric current, as in a counting-rate meter. These devices usually consist of a capacitor that is charged by the pulses and a re-... 

X-ray measurements are made by automatic scanning through the peak and adjacent background with recording of the rate-meter output. 

A variable-area, fluid or gas flow-rate meter. Usually a cone inside a glass measuring cylinder that is suspended by the upward flow of gas or liquid. 

Rate Meter Measures the instantaneous volume flow rate through the sampling systems. An example would be a rotameter or venturi meter. Used to set precise flow rate for flow sensitive sampling devices. 

Figure 5.6. Diagram of a low-energy, high-angle electron-impact spectrometer. (A) Electron gun (B) monochromator (180° spherical electrostatic energy selector) (C) electron optics (D) scattering chamber (E) analyzer (180° spherical electrostatic energy selector) (F) electron multiplier (G) amplifier and pulse discriminator (H) count-rate meter (I) multichannel scaler (J) X Y recorder (K) digital recorder. (After Kupperman et a/.<42))...

The heart of the Data Acquisition System is the HP-85 (Hewlett-Packard, 1982) microcomputer which has been interfaced to a Wrenn Counter (Wrenn ert aj., 1975) using a Ludlum model 2200 scaler rate meter (Ludlum Measurements, Inc., 1982), a Rainwise weather station (Rainwise, Inc., 1984), and a water meter. These various components are interfaced to the HP-85 via a peripheral interface circuit as shown in the block diagram of Figure 1. For the interface to function properly, the General Purpose I/O (GPIO) has been configured such that two of its ports (A and B) form a 16-bit input port while ports C and D form a 16-bit output port. 

Under normal operating conditions the system is designed to acquire data from the peripherals at times determined by the preset time on the scaler rate meter. When the rate meter finishes its time interval the interface is signaled to acquire the stored... 

The number of ionizations or scintillations detected by both types of detector is measured electronically and presented either as the total number of counts (a scaler) or as the number of pulses per minute (a count-rate meter)... 

The rate meter provides the required high voltage for (he photomultiplier iibes and converts the digital signal obtained from the scintillation crystal to an analog output for the recorder. 

The discriminator produces an output pulse with a fixed shape (generally square) and size when the input signal crosses a reference. Discriminators usually have multiple identical output signals. The logic pulses can be sent to a scaler that simply counts the number of pulses, to a count rate meter to monitor radiation rates or doses, and to a time-to-amplitude converter (TAC) to measure the relative times of arrival of two or more logic signals. 

A collimated beam of 7-rays (Fig 3), provided by a shielded 3.5-curie source of Cobdlt-60, is transmitted thru the rocket motor walls and is transformed into an electrical feedback signal by a 7-ray detector coupled to a linear rate meter. 

A permanent record of the rates during detonator scans was made with a strip chart recorder connected to a nuclear rate meter a more accurate record was also made of the counts per unit time with a high speed printer coupled to a multichannel analyzer... 

Typical scans of an M-55 detonator are reproduced in Fig 7, showing the rate meter plots corresponding to the y-ray transmission profile thru the detonator. Starting with copper as a standard, a large increase in transmission is obtained as the beam transverses thru the RDX layer, and a corresponding decrease occurs thru... 

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 applies 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 manner. The term rate meter applies to all types of flowmeters through which the material passes without being divided into isolated quantities. Movement of the material is usually sensed by a primary measuring element that activates a secondary device. The flow rate is then inferred from the response of the secondary device by means of known physical laws or from empirical relationships. 

Effluent solution from the ion exchange column is passed through an in-line alpha-detector which activates a count-rate meter and recorder outside the cell. Inside the detector/ the liquid flow is passed adjacent to a Mylar film-covered window/ which separates the liquid from the silicon diode detector. 

Equation (8) was derived by Stern and Geary [10] and is the theoretical principle upon which many commercial corrosion rate meters operate. 

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