SONIC NOZZLE CALIBRATION DEVICE FOR GAS FLOW METERS (DN400 CAPABLE)

WHEN GAS FLOW IS NO LONGER MEASURED — IT IS RECONSTRUCTED

Gas flow calibration is not about “reading a value”.

It is about recreating a flow condition that is physically stable enough to be trusted.

The Sonic Nozzle Calibration Device is designed for that purpose:
to generate a known, repeatable, and choked-flow reference condition for gas flow meter verification.

And in DN400 systems, this challenge becomes significantly more demanding.

THE PRINCIPLE: FIX THE FLOW BY FIXING THE PHYSICS

Unlike conventional calibration methods that rely on variable flow generation, sonic nozzle systems operate under a different rule:

Once the flow reaches sonic velocity at the nozzle throat, the mass flow becomes independent of downstream pressure fluctuations.

This creates a natural reference point where:

• flow becomes predictable
• instability is isolated
• measurement comparison becomes meaningful

The calibration system does not “control flow”.

It locks the flow condition into a physical limit state.

WHY DN400 CHANGES EVERYTHING

At DN400 scale, gas calibration is no longer a laboratory task.

It becomes an engineering system challenge involving:

• large volume stabilization
• pressure uniformity across wide diameter pipelines
• nozzle array balancing
• flow distribution symmetry

Small disturbances at this scale do not disappear.

They propagate.

So the system design must ensure that:

the reference condition remains stable even when the flow domain becomes large