Download Church Fashion Show Program. When a fluid flowing through a pipe assumes a desirable flow profile, it moves uniformly with the greatest velocities near the center of the pipe. Improper flowmeter installation can disturb this profile and degrade measurement accuracy. Flow-profile distortion and swirl — the two most prominent types of fluid disturbance that affect a meter’s flow coefficients — are typically the products of improper piping configuration. Fluid profile distortion occurs when an obstruction — such as a partially open valve or a poorly mounted flange gasket — partially blocks the pipe. Swirl occurs when the fluid moves through piping bends in different planes.

Swirl is far more difficult to correct than flow-profile distortion. Obstructions upstream and near the flowmeter can cause errors ranging beyond 50 percent. Flowmeter manufacturers will recommend various lengths of straight pipe upstream and downstream of the flowmeter to attain a fully developed desirable flow profile. Long straight-pipe lengths can be avoided through the use of flow-straightening devices and flow conditioners. Flow-straightening devices include tube bundles, perforated plates, and internal tabs. These solutions reduce swirl, but not flow profile variations; some may even introduce a distorted profile. Flow conditioners can reduce swirl and also mimic a fully developed profile.

Some Guidelines, Standards Applied for Flow Metering from Number of Organizations by bagusindarto in Types >Books - Non-fiction and list standards in flow metering. Flowmeter installation guidelines are rooted in flowmeter piping requirements, which play a key role in determining the technology specified for a given application.

A grated plate, for example, can introduce such a profile. Differential-pressure flowmeter piping requirements DP flowmeters measure the drop in pressure across a flow element in the piping, such as an orifice plate. The measured flowrate is a function of the pressure drop. So the flowmeter consists of the flow element in the piping, as well as a nearby differential-pressure meter.

Small tubes, called impulse lines, on either side of the flow element lead to the DP meter for measurement. Professional organizations, such as,,,, and, offer installation guidelines for DP flowmeter installations.

These guidelines help to minimize disturbances to the fluid-velocity profile. Often, for example, measurements of temperature and static pressure are desirable in addition to flowrate. To minimize flow disturbances from an added pressure sensor, install a tee for connection to the appropriate DP impulse line. Homem.aranha.2099 Pdf here. Similarly, install a thermowell used for temperature measurement at least 10 pipe diameters downstream of the flow element. Such installations should be characterized by smoothly ground welds and trimmed gaskets to eliminate protrusions into the fluid stream. Straight-pipe runs upstream and downstream from the DP flow element help to guarantee a fully developed fluid-velocity profile that permits a predictable pressure drop. For an orifice, the length of straight run required depends on both the beta ratio of the installation and on the nature of the upstream components in the pipeline.

(Beta ratio is the diameter of the orifice divided by the pipe diameter.) For example, when a single 90-degree elbow precedes an orifice plate, the straight-pipe requirement ranges from six to 20 pipe diameters as the beta ratio increases from 0.2 to 0. Hotel Bella Vista Roatan Honduras here. 8. The size and orientation of the impulse-line pressure taps depend on both the pipe size and the process fluid. The recommended maximum diameters of pressure-tap holes through the pipe or flange are: • ¼ inch for pipes under two inches in diameter; • 3⁄8 inch for two- and three-inch diameter pipes; • ½ for four- to eight-inch diameter pipes; and • ¾ inch for pipes larger than eight inches in diameter.

Size both pressure taps and leads with the same diameter. Where the hole breaks through the inside pipe surface, make sure it is flush with the inside pipe surface with no roughness, burrs, or wire edges. Connections to pressure taps should be made by nipples, couplings, or adaptors welded to the outside surface of the pipe. On services where the process fluid can plug the pressure taps or might gel or freeze in the impulse lines, consider chemical seals. Connection sizes are usually larger in these cases. When using chemical seals, assure that the two connecting capillaries that route to the DP meter experience the same temperature and keep them both shielded from sunlight.