Orifice flow meter plus air blowing

There is a problem with the blow pipe. The two pressure tubes must control the air intake respectively, and one control element cannot be used to output two air intakes. Orifice plate blowing is possible. The premise is that the pressure pipe from the sampling port to the blowing inlet is thick enough and the blowing volume must be well controlled. In addition, one control element cannot be used to output two air intakes. .

Instead of using one control element to output two channels of air, how can we make the two channels of air blowing exactly the same? If you use two control originals and perform migration without traffic, it won't work! Adding control components increases the failure rate. Is it feasible to add one-way check valves to the two blow pipes?

What medium is this measured on?

Why don't you see the flow-restricting orifice plate?

. If one air source is divided into two channels and connected to the pressure pipe, it will cause the differential pressure signal to short-circuit, and the effect is similar to opening the balance valve. The error caused by blowing measurement comes from the pressure drop caused by the blowing air flow when it flows through the pipeline, which is mainly related to the flow rate and pipeline resistance. ； Under the conditions that the inner diameter of the pressure-inducing pipe is not less than 12 mm, the air volume is 5 l/h, and the pressure-inducing pipe does not exceed 10 m, the impact will not exceed 50Pa (actually it rarely reaches more than 20Pa) ； Therefore, for differential pressure measurement of 1KPa and above, the error of air blowing is acceptable. This includes the situation where the air volume difference between the two sides reaches 5 l/h (approximately 5% error). .

Backflush is possible, but looking at the picture, the joint seems to be socket welded or butt welded. It doesn't look like there is a union. It is said that the flow-limiting orifice plate is inside the union.