Consumption must be measured at the workstation

A meter on the main line shows the consumption of the entire hall, but does not indicate which machine is using too much gas. A flowmeter at the workstation makes it possible to compare consumption during production, start-up, downtime and recipe changes. The operator can then distinguish the actual process requirement from losses caused by a leak or incorrect settings.

It is worth recording two parameters: instantaneous flow and total consumption. The first quickly reveals spikes and instability. The second shows how much gas the machine used during a shift, batch or single cycle. Digital devices can transmit this data to a PLC controller or supervisory system via an analogue signal or industrial interface. The red-y smart series supports, among other things, Modbus RTU, Profinet RT and EtherCAT, while the built-in totalizer counts the total flow.

Stable flow limits excessive dosing

A manual valve does not maintain a constant dose when the supply pressure or gas temperature changes. The operator often sets a higher flow to avoid a decline in product quality. This creates a reserve that the process does not use.

A mass flow controller measures the gas stream and adjusts the valve position according to the setpoint. This control makes it possible to reduce the flow to the level required in a given process phase. During welding, a higher flow can be used for initial purging, and then reduced to a stable operating value. A controlled protective atmosphere limits gas consumption and helps maintain consistent weld quality.

When selecting a device, it is necessary to consider the type of gas, flow range, pressure upstream and downstream of the regulator, temperature, required response time and communication method. An oversized meter may operate at the lower end of its range, where it is more difficult to accurately assess low consumption. An undersized controller will limit the flow during start-up or peak demand.

Flow during downtime reveals leaks

After the machine stops, the flow should fall to a value consistent with the process procedure. Constant consumption during downtime often indicates a leaking valve, quick coupling, hose, pipe or threaded connection. Typical leak locations in gas and pneumatic installations also include regulators, filters, seals and device connections.

The inspection should include:

  • reading the flow with the machine switched off,
  • testing the tightness of pipes and connections,
  • marking the location of the leak,
  • repairing it and measuring again,
  • recording the result and the date of the next inspection.

Operating pressure affects the size of the loss. The higher the pressure in a leaking system, the faster the gas escapes from the installation. Therefore, the regulator setting should not be increased “as a reserve”. It is better to establish the minimum pressure that ensures correct operation of the point-of-use device.

Automatic shut-off prevents consumption outside the cycle

Gas should not flow during breaks, changeovers or while waiting for a part if the process does not require it. The controller can close the valve after a cycle-end signal, when the line stops or when the idle time limit is exceeded. It is worth linking the flow to the presence of a part, burner operation, the welding arc or the state of the machine guard.

A tight control valve limits flow after closing. red-y smart regulators use valves with a declared leak rate below 1 × 10⁻⁶ mbar l/s of helium, while the fast response facilitates control of short dosing cycles.

Flowmeter data help maintain consistent standards

A one-time adjustment is not enough. Nozzles wear out, pipes become damaged and operators change the settings. The plant should define the correct consumption for the product, program and workstation, and then set alarm thresholds. An increase in consumption may indicate a leak, a worn nozzle or an incorrect recipe. A decrease may signal a blocked pipe or excessively low pressure.

If you are looking for devices for monitoring consumption and precise gas dosing, see the offer from Newtech Engineering. The company supplies Vögtlin gas flowmeters, mass flow controllers and solutions for communication with automation systems, while technical support facilitates the selection of the range, design and control method for a specific workstation.