Static pressure tap
correction for the ASME Throat Tap Nozzle.
Estimated errors are in measured pressure associated with the different pressure tap
where p(x, z) is the averaged pressure measured at each pressure tap
on the model surface (x and z stand for the pressure tap
coordinates in a reference frame indicated in Figure 1; see also Table 1).
When the impeller was pumping upward the fluid velocities near the pressure tap
increased thus reducing the pressure readings as the impeller speed was increased.
These meters have no downstream and shorter upstream straight pipe requirements for standard accuracy, have lower head-loss, and are less susceptible to blockages and plugging as the annular chamber was replaced with a single pressure tap
. They are more accurate than most other meters as typical head-loss percentages for modified short form meters range from 3.0 to 10.0 per cent of differential depending on Beta ratio selected.
Figure 2 shows a single chamber orifice meter with a downstream pressure tap
and an extra DP transmitter.
As mentioned, the conventional pressure tap
approach provides good information.
Since the distance between this y-section and the first pressure tap
is around 1.87 m, then a fully developed flow can be achieved easily before taking measurements.
The problems of centering the plate, alignment of the inlet and outlet piping, and pressure tap
to plate dimensions have also been solved using standard fittings and patented plate holder designs.