Orifice flow test

NTIS U.S. National Technical Information OFT orifice flow test... 

The orifice flow test involves the use of a mold with a lower plate containing a cavity into which a measured quantity of room-temperature compound is placed. The upper plate has a plunger with two small orifices cut into the outer circumference. The test generally uses a charge of 12-15 g and a mold temperature of 150°C. Various pressures can be applied, depending on the molding process to be used. With the mold charged, the heated platens of the press close, and the compound is forced... 

Flow. The free flow of a powder through an orifice depends on the orifice which is standardized for the testing of the powder (14). Flow, therefore, depends not only on friction between powder particles, but also on friction between the particles and the wall of the orifice. Flow is usually expressed by the time necessary for a specific amount of powder (usually 50 g) to flow through the orifice. 

When testing to estabhsh the thermodynamic performance of a steam turbine, the ASME Performance Test Code 6 should be followed as closely as possible. The effec t of deviations from code procedure should be carefully evaluated. The flow measurement is particularly critical, and Performance Test Code 19 gives details of flow nozzles and orifices. The test requirements should be carefully studied when the piping is designed to ensure that a meaningful test can be conducted. 

At an ASME-approved flow facility, a total of 9 valves of a particular valve design or range are flow tested at 10% overpressure above set pressure. They select three valve sizes and three set pressures. This way they establish the KD factor of each test valve, considering the flow conditions and each measured orifice area. 

Inspection and Preventive Maintenance As with all water-based extinguishing systems, particularly those installed outside, inspection and preventive maintenance are critical to reliable operation. Detection devices are typically inspected, tested, and maintained quarterly or at a frequency deemed more appropriate for a particular location. The water-spray system itself is typically flow-tested at least annually (NFPA 25, 1995). Because of the nozzles small orifice size, scale and corrosion buildup can compromise flow and spray patterns. The use of strainers and the conduct of flow tests will help minimize this potential problem. As stated earlier, preventive maintenance of the overall water supply and distribution systems is an integral part of a reliable system. 

Other Methods of Flow Characterization A variety of other test methods to characterize flowability of powders have been proposed, which include density ratios, flow from funnels and orifices, angles of repose and sliding, simplified indicizer flow testing, and... 

Noise is often defined as unwanted sound. There are many possible sources of noise in industrial combustion testing (see Chapter 8). Some of these include combustion roar, jet noise for flow through orifices, flow noise for fluids flowing fhrough piping, and equipment noise such as from fhe combustion air fan. Acoustic resonance can exacerbate the problem by magnifying the noise. 

Orifice flow i (test and moid) (Fig. 2.25). This flow test involves the use of... 

Carson (49) has tested these features for numerous papers. For the thinnest tissues the behaviour with respect to Ap suggested that flow might be intermediate between streamline and orifice flow. Within the uncertainties of using different samples an inverse proportionality existed between the permeation velocity and the thickness, while a small change in temperature had a negligible influence upon the rate of flow. The results are on the whole more in conformity with Poiseuille flow than with orifice flow. The effect of altering the absolute pressure pj, for a constant Jp, however, was not in accord with either theory, and was attributed by the author to elastic deformations of the membrane under pressure. In addition, an approximate proportionality between area and diffusion... 

CIL Flow Test A capillary-rheometer test developed at Canadian Industries Ltd for characterizing the flow of thermoplastics. The reported flow unit is the amount of melt that is forced through a specified orifice per unit time when a suitably chosen force is applied. Similar to... 

Orifice flow ii (test and mold) (Rg. 2.2 ). As shown, the mold has a pot in the lower half and a plunger affixed to the top half. The pot block is designed with a sprue hole in the bottom of the cavity, which feeds the molding compound into a runner that comes out one side of the mold. The pot is charged with 90 g of compound, and the mold is closed under 1000 Ib/in with a mold temperature of 300°F (148°C). The compound exiting from the runner can he weighed once the flow has ceased. If the time of flow from the start has been timed from start to finish, the rate of flow can he calculated as X g/s. This is a very useful tool for use in transfer or injection molding of thermosets. 

The liquid hydrogen was transferred from the pressurized supply dewar through the vacuum-insulated lines, the orifice flow meter, the test section, and into the receiving dewar. Data were taken after steady state, as indicated by a steady orifice reading, was attained the data consisted of pressures, temperatures, flow rates, time of day, and ambient conditions (i.e., atmospheric temperature and pressure, humidity, and wind velocity). Two wind velocities were used in these tests a steady wind velocity of 15mph supplied by two 24-in. fans, and zero wind velocity. 

Viscosity. Although traditionally of Httle importance in the evaluation of vegetable and insect waxes, viscosity is an important test for mineral and synthetic waxes. One of the most frequently used tests, ASTM D88, is used to measure the time in seconds required for a specified quantity of wax at a specified temperature to flow by gravity through an orifice of specified dimensions. This viscosity is expressed in Saybolt Universal Seconds (SUS) at the temperature of the test. The SI unit for kinematic viscosity is mm /s (=cSt). 

Lucas and Porter (U.S. Patent 3,370,401, 1967) developed a fiber-bed scrubber in which the gas and scrubbing liquid flow vertically upward through a fiber bed (Fig. 17-55). The beds tested were composed of knitted structures made from fibers with diameters ranging From 89 to 406 [Lm. Lucas and Porter reported that the fiber-bed scrubber gave substantially higher efficiencies than did venturi-type scrubbers tested with the same dust at the same gas pressure drop. In similar experiments, Semrau (Semrau and Lunn, op. cit.) also found that a fiber-bed contactor made with random-packed steel-wool fibers gave higher efficiencies than an orifice contactor. However, there... 

Instrumentation Calibration may be required for the instruments installed in the field. This is typically the job of an instrument mechanic. Orifice plates should be inspected for physical condition and suitabihty. Where necessary, they should be replaced. Pressure and flow instruments should be zeroed. A prehminary material balance developed as part of the prehminary test will assist in identifying flow meters that provide erroneous measurements and indicating missing flow-measurement points. 

In the sampling train itself, the gas flow must be measured to determine the sample volume. Parhculates and gases are measured as micrograms per cubic meter. In either case, determination of the fraction requires that the gas volume be measured for the term in the denominator. Some sample trains contain built-in flow-indicahng devices such as orifice meters, roto-meters, or gas meters. These devices require calibration to assure that they read accurately at the time of the test and under test conditions. 

ASMEflow nozzle. These nozzles provide for accurate measurements. Their use is limited because they are not easily placed in a process plant however, they are excellent for shop tests. Venturi meters and nozzles can handle about 60% more flow than orifice plates with varied pressure losses. 

The most difficult part of a field test is the flow meter, if it wasn t planned in the construction phase. There is no way to simulate a meter run if you don t have the proper pipe length. Figure 10-8 is an example of the requirements. An ASME long radius flow nozzle is preferred by the author, though a short throat venturi will do. The probability is that an orifice is all that will be available. It should be examined before and after the test to verify not only the bore diameter, but the finish. The bore should... 

More accurate measurement of air flow can be achieved with nozzles or orifice plates. In such cases, the measuring device imposes a considerable resistance to the air flow, so that a compensating fan is required. This method is not applicable to an installed system and is used mainly as a development tool for factory-built packages, or for fan testing. Details of these test methods will be found in BS.1042, BS.2852, and ASHRAE 16-83. 

Saybolt Universal Seconds (SUS) are used to measure viscosity. The efflux time is the SUS required for 60 mL of a petroleum product to flow through the calibrated orifice of a Saybolt Universal viscometer, under carefully controlled temperature and as prescribed by test method ASTM D 88. This method has largely been replaced by the kinematic viscosity method. SUS is also called the SSU number (Seconds Saybolt Universal) or SSF number (Saybolt Seconds Furol). 

Murdock (1962) has tested the two-phase flows of steam-water, air-water, natural gas-water, natural gas-salt water, and natural gas-distillate combinations in 2.5-, 3-, and 4-in. pipes with orifice-to-pipe diameter ratios ranging from 0.25 to... 

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