Vortex street flowmeter national execution standard

Vortex flowmeter implementation standard, although the vortex flowmeter in the general flowmeter is a very young flowmeter, China as early as in the 1980s to develop the vortex flowmeter professional standards (zbn12008-89) and verification procedures jjg620-89, it shows that it is valued by the industry.The professional standards were revised in 1998, changing to JB/ t9249-1999.

Verification procedures are combined with other firm procedures for velocity flowmeters into a new verification procedure jjg198-94, but because the new procedure includes many types of velocity flowmeters (up to 8!)It is difficult to take into account some of the characteristics of vortex flowmeters in the regulations. Therefore, it is difficult to carry out some of the regulations because some of them are not specified or not specified at all.Jjg620-89 still has certain reference value.

In the early 1990s, the international organization for standardization (ISO) established a working group to draft the VSF international standard. In 1993, the draft of the committee was proposed (ISO/CD12764), which was promulgated as a technical report (ISO/TR12764:1997).For a variety of reasons, ISO lists some documents that are not suitable as international standards as technical reports, such as documents that do not have sufficient support, technologies are not mature enough or provided as reference materials, etc. It seems that vortex flowmeter documents are not mature enough and cannot be issued as international standards for the time being.Industrial developed countries such as the United States and Japan have developed VSF national standards (ASME/ ansimfc-66-1987 and jisz8766-1989).

Notes for initial installation of vortex flowmeter

(1) check the vortex street flowmeter before power on and current passage after on-site installation

1) each flange, valve, pressure hole, temperature hole and joint on the main pipe and bypass pipe shall be free from leakage;

2) whether the pipeline vibration meets the requirements of the specification;

3) is the sensor installed correctly?Is the electrical connection of each part good?

(2) power on static debugging

The converter should have no output when the power is turned off, the instantaneous flow indication is zero, and the accumulated flow is unchanged. Otherwise, first check whether interference signals are introduced due to signal line shielding or poor grounding, or strong vibration of the pipeline.If the above reasons are not confirmed, the potentiometer in the converter can be adjusted to reduce the amplifier gain or raise the trigger level of the shaping circuit until the output is zero.

(3) flow dynamic debugging

Close the bypass valve and open the upstream and downstream valves. When the flow is stable, the converter outputs continuous pulse with uniform pulse width.Otherwise, the potentiometer should be carefully checked and adjusted until the output of the meter is triggered correctly and there is no leakage pulse.If there is any instrument fault, please refer to table 7.

(4) instrument coefficient correction

The meter coefficient of vortex street flowmeter is verified in the laboratory condition, and the working condition deviates from the laboratory condition when it is used in the field