Inline Thermal Mass Flow Sensor WAFS 105

Where the WAFS 105 inline flow meter fits

The WAFS 105 is the inline member of the thermal mass range, made for pipe sizes DN15 to DN80 with R thread, EN1092-1 or ANSI B16.5 flanged connections. Because the meter body defines the bore, the flow profile through the sensing element is known rather than inherited from your pipework — which is why an inline instrument is the more repeatable choice on small lines.

That makes it the right specification for branch drops, departmental sub-metering and machine feeds, where an insertion probe in a 25 mm pipe would occupy too much of the bore to measure cleanly.

Inline or insertion?

The trade-off is straightforward. The WAFS 105 needs the line opened to fit, and gives you a defined bore and better behaviour in short straight runs. The WAFS 104 insertion meter fits through a 1/2 inch ball valve under pressure with no shutdown, and suits DN20 to DN1000. On anything above DN80 the insertion type is the practical answer; below it, the inline usually measures better.

What to tell us when you enquire

• Nominal pipe size — DN15, 20, 32, 40, 50, 65 or 80.
• Connection type — R thread, EN1092-1 flange or ANSI B16.5 flange.
• Expected flow range and line pressure, so the instrument is sized on real duty rather than on pipe size alone.
• Output required — RS485 Modbus RTU, 4–20 mA, pulse, or a combination.
• Straight run available upstream and downstream of the proposed location.

The instrument measures standard flow, mass flow, cumulative consumption and temperature, with no moving parts to wear and a stable signal under vibration.

Frequently asked questions

Does an inline meter need less straight pipe than an insertion meter?

Generally yes, because the bore is defined by the meter rather than by your pipe. It still benefits from straight run — aim for as much as the layout allows, and tell us what you have so we can advise on the mounting position.

Can I fit it without stopping production?

No. An inline meter replaces a section of pipe, so the line has to be depressurised. If you cannot take a shutdown, specify the WAFS 104 insertion meter instead.

Will it measure gases other than compressed air?

Thermal mass instruments are calibrated for a specific gas. Tell us the gas at the enquiry stage — nitrogen and other industrial gases are commonly supplied.

What units does it report?

Standard or normal flow directly, so no pressure and temperature correction is needed downstream. Use the flow unit converter if you need CFM or SCFM for a report.

Related: compare all WiseAir flow meters · WAFS 104 insertion meter · flow unit converter.