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Vortex Flow Meter DN100: Four-Inch Nominal Diameter Steam Sensor Specs

Quick Answer

For a DN100 (4-inch) steam line, the Silver Instruments vortex flow meter delivers a direct mass or volume reading without moving parts. It handles saturated and superheated steam up to 350 °C with a standard 4-20 mA HART output. Most site teams pair it with an integrated PT100 RTD for density compensation and a totalizer readout in kg/h or t/h.

Why a DN100 Vortex Meter Still Dominates Steam Measurement

Engineers in Southeast Asia and the Middle East often ask us the same question. They have a 4-inch steam header that runs 24 hours a day. They need a meter that survives sudden pressure swings during boiler cycling. The vortex principle does this well because it has no internal bearings, no lubricated gears, and no parts that wear against each other. The blunt shedder bar sits directly in the flow stream. As steam passes around it, alternating vortices form at a frequency proportional to flow velocity. A piezoelectric sensor sealed inside the meter body detects that frequency and converts it to an analog signal.

The Silver Instruments DN100 vortex flow meter comes with a standard wafer or flanged connection. For saturated steam at 10 bar, a typical 4-inch line flows between 300 kg/h at low fire and 5 000 kg/h at peak demand. The meter stays within ±1% of reading across the top 80% of that range. At very low flows, when the Reynolds number drops below 10 000, accuracy falls off. Most engineers skip that part because low-flow steam often condenses anyway.

We have seen this on customer sites many times. A palm oil refinery in Indonesia ran a DN100 meter on their steam distribution line for three years without recalibration. They only wiped the sensor face during annual shutdowns. The meter held its factory calibration because the piezoelectric crystal does not drift like older capacitive designs.

Sensor Specs That Matter for Steam

When you spec a DN100 vortex meter for steam, four numbers decide success or failure. The first is temperature rating. A standard Silver Instruments sensor handles 200 °C continuous. The high-temperature version uses an all-welded sensor capsule rated to 350 °C. That covers superheated steam at 30 bar without needing a separate cooling tower. The second number is pressure rating. Our DN100 body is standard at PN40 for flanged units, and we offer PN63 on request. A carbon steel body covers most steam loops. For corrosive condensate, we supply 316L stainless steel.

The third factor is the integrator or flow computer. Steam density varies with pressure and temperature. A standalone vortex meter without compensation assumes a fixed density. That works for saturated steam only if you hold pressure very steady. In practice, the boiler pressure drifts. An integrated PT100 RTD inside the meter body or a remote pressure transmitter wired to the flow computer corrects density in real time. The output then reads directly in kg/h or tonnes per hour. The fourth factor is turn-down ratio. A DN100 meter typically gives a 20:1 usable range on steam. If your minimum flow is below 200 kg/h, a DN80 meter with a reducer might perform better. We size every meter against your actual minimum and maximum flow data. Send us your pressure in bar, temperature in °C, pipe size in DN, and flow range in kg/h. We return a sizing report the same working day.

Installation Truths Engineers Learn on Day One

Vortex meters need straight pipe. For DN100 steam lines, we specify 15 diameters upstream and 5 diameters downstream when a single 90-degree elbow sits before the meter. A control valve or two elbows in different planes requires 30 diameters upstream. If the steam line sits outdoors in a tropical climate like Vietnam or the Philippines, we recommend insulating the gaskets and body but not the electronics housing. Condensation inside the terminal box kills the s