Pressure gauge method

The hose-and-pressure gauge method of estimating head for a hydro-eleetrie system results in a value that represents static head, where the water is at a standstill in the pipe. With the lower ball valve closed, the reading on a nearby pressure gauge will reflect this static head. In this system, the pressure gauge read 50 psi. 

Also ealled the DUH Factor. You ll need to gather information from pressure gauges mounted to the existing system. With the previously mentioned formulas, the Hf and the Hv are estimated in the initial phase when everything is new. The Baehus Custodio method measures the exact Hf and Hv in any existing system. It doesn t matter when it was built. 

The evaluation methods could be direct, e.g., measuring a containment index, or indirect, e.g., measuring pressure loss or velocity distribution. The direct methods are used to measure the performance of a hood or an inlet during periodic preventive maintenance. Indirect methods are used for verifying or checking on a daily basis (routine checks). How often each method is used depends on the availability of instrumentation and qualified personnel, since direct measurement of a hood s performance can be both expensive and difficult. On the other hand, indirect methods are usually easier to use and can sometimes include inexpensive, continuously monitoring instruments (pressure gauges or velocity indicators). 

When using a rupture disc followed by a spring-operated relief, it is important to periodically check the pressure gauge to be sure that there is no pinhole leak in the rupture disc. Describe several methods to satisfy this requirement. 

A number of techniques are based on direct measurement of the total vapour pressure in equilibrium with a compound at a given temperature, i.e. equilibration methods. The most usual methods are based on the use of pressure gauges covering pressures from 10-7 to 100 kPa [93], Methods based on thermogravimetric determination of the mass of the vapour [94] and on atomic absorption spectroscopy have also been reported [95],... 

Pressure filters, 76 658-659 horizontal belt, 77 379 thickening, 77 382-388 Pressure gauge, 20 645 Pressure gradients, flow caused by, 9 110 Pressure infiltration, of metal-matrix composites, 76 167-169 Pressure injection, moldings, 10 11 Pressure-jump method, 73 427-428... 

In addition, compression methods that utilize hydraulics and levers may be used. These sometimes have pressure gauges that allow the analyst to apply a certain optimal force in order to maximize the chances of making a quality pellet. To make a quality pellet, in addition to using the optimum pressure, it is important for the KBr and the sample to be dry, finely powdered, and well mixed. An agate mortar and pestle is recommended for the grinding and mixing of the KBr and sample prior to compression. See Workplace Scene 8.3. 

Examples of fundamental pressure measurement methods (as standard methods for ealibrating vacuum gauges)... 

Different methods used for calibrating samplers include rotometers, wet-test meters, pressure gauges across fixed orifices, mass flow meters, hot wire flow meters and bubble tubes. Each of these calibration devices requires an appropriate correction factor. Some of the devices measure mass flow rather than volumetric flow. Sampling requires volumetric flow calibration. 

Pressure is measured extensively in the chemical processing industries and a wide variety of pressure measuring methods has been developed. Some of these have already been discussed in Volume 1, Section 6.2.2, viz. the manometer (which is an example of a gravity-balance type of meter), the Bourdon gauge (an example of an elastic transducer) and mention is made of the common first element in most pressure signal transmission systems—the differential pressure (DP) cell (Volume 1, Section 6.2.3). The latter also frequently forms part of a pneumatic transmission system and further discussion of this can be found in Section 6.3.4. 

Electronic manometers provide a convenient method of pressure measurement in a tensimeter, and the general arrangement may be very simple (Fig. 9.3). The one problem which must be anticipated is long-term zero pressure drift, which can be encountered with an electronic pressure gauge. Drift is minimized by maintaining a constant temperature on the pressure transducer and by avoiding mechanical vibration at the transducer. 

C, static method-pressure gauge measurement Antoine eq., measured range 0.36-169°C,... 

Liquid level measuring devices are classified into two groups (a) direct method, and (b) inferred method. An example of the direct method is the dipstick in your car which measures the height of the oil in the oil pan. An example of the inferred method is a pressure gauge at the bottom of a tank which measures the hydrostatic head pressure from the height of the liquid. 

The measurement of total pressure in a vacuum system is essential. Chapter 5 outlined the two general principles involved (direct and indirect). Direct methods included manometric measurements (Examples 5.1 and 5.3) and those involving the mechanical deformation of a sensing element. Indirect methods, which depend on the estimation of a physical property of the gas (e.g. thermal conductivity, ionisation) that depends on number density, were also discussed. Uncertainty of measurement is a parameter associated with the result of a measurement. It may influence the choice of a pressure gauge, and its practical expression was illustrated in Example 5.4. 

Chapter 5 considers the methods available for the measurement of both total and partial pressure in vacuum systems. For total pressure, the methods of measurement are described and, importantly, the uncertainty associated with that measurement is discussed. This may influence the choice of gauge. Also in Chapter 5, residual gas analysers (RGAs) for vacuum partial pressure measurements are described. These devices are being used increasingly for diagnostic work on vacuum systems. 

The establishment of the International Temperature Scale has been accomplished largely with the aid of measurements made with the helium gas thermometer. The most precise gas thermometry method is the constant-volume method, in which a definite quantity of the gas is confined in a bulb of constant volume Eat the temperature T to be determined and the pressure p of the gas is measured. A problem is encountered however in measuring the pressure a way must be found to communicate between the bulb and the pressure gauge. This is usually accomplished by connecting the bulb to the room-temperature part of the system by a slender tube and allowing a portion of the gas to occupy a relatively small, constant dead-space volume at room temperature. Thus, it is important that the gas volume in the pressure manometer be as small as possible. 

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