Superheated Steam Flow Meter

In the saturated region, temperature and pressure are linked; knowing one fixes the other on the steam curve. In the superheated region, T and P are independent: the same pressure can sit at any temperature above saturation, and density changes sharply with both. A single-sensor correction (temperature-only, or pressure-only) drifts 5–15% off true mass flow across a normal operating range. A superheated steam flow meter with on-board dual T+P compensation stays within ±1.0% of kg/h because it reads the real density point on the superheated steam chart.

The compact integrated housing is rated for a 70 °C ambient. On main-steam lines above 350 °C with uninsulated flanges or inside a turbine hall with radiated heat, the local ambient at the meter body easily exceeds 80 °C, which shortens electronics life. Specify the remote version (4 m armoured signal cable between the flow body and the electronics enclosure) whenever pipe surface temperature exceeds 350 °C, installation is inside a turbine hall, or the meter sits in direct sunlight in a hot climate.

Standard ship-kit includes a factory calibration certificate traceable to national standards, hydrostatic pressure-test record, and a declaration of conformity. Flange dimensions follow ANSI B16.5 (ANSI 150–900 LB) or DIN EN 1092-1 (PN16–PN40) per order. Hazardous-area units ship with CNEX explosion-proof certificates (T-class confirmed against the project’s process-temperature range at quotation). If your project specification names a specific code stamp not listed here, send the requirement on the quote and our engineering team will confirm what we can meet before you commit.

316L is the standard wetted material and is fine for clean dry superheated steam up to 400 °C (T3 code) with normal boiler-feedwater chemistry. Upgrade to Hastelloy C-276 when any of the following apply: (a) known chloride contamination in the steam (reformer steam, some geothermal sources), (b) process-steam cracking service with trace catalyst carryover, (c) site specification calls for it. Hastelloy wetted parts add roughly 35–45% to the unit price; the engineering team confirms whether it’s actually needed based on your process data sheet rather than upselling by default.

Start from your minimum and peak steam flow rate (kg/h) on the bypass; that pair sets the turndown ratio the meter has to span across the operating range. Turbine bypass lines swing from zero during normal operation to full main-steam flow during startup, trip, or load rejection; a turndown that generic vortex meters (1:10) cannot span. Specify the LUGB-VRd version with 1:70 turndown so one meter reads accurately from low warming-flow (a few percent of rated) up to full bypass service. On the steam main itself, 1:15 standard is usually enough because the machine operates close to rated output.

The LUGB installation rule is 10× DN upstream and 5× DN downstream of clean straight pipe at the nominal meter diameter. The critical item is not just length but disturbance type; a reducer immediately upstream is more demanding than simple straight run, and two elbows in different planes make the problem harder. If you cannot meet the full 10D/5D in a retrofit, tell the engineering team the actual straight-run available and the upstream disturbance, and they will advise whether the VRd version’s wider turndown can absorb the extra uncertainty or whether the install has to be relocated.

Three steam flow meter types see real service on superheated lines: orifice plate with DP cell (cheap, short-lived, needs separate density correction), Coriolis (accurate but pressure-drop and cost scale hard above DN100), and vortex (no moving parts, low pressure drop, accurate once T+P is on-board). For superheated steam flow meter selection above DN50 and up to DN400 within the LUGB 400 °C T3 range, vortex wins on total cost of ownership; one wetted assembly, no fill fluid, on-board density correction. Our engineering team reviews your P/T/flow range and returns a sized model code within 4 business hours; shipping is 5–7 business days from order lock.