Orifice Plate Flow Meter
ISO 5167 Primary Element, DN15-DN6000
±0.5 % of flow on the primary; system spec also depends on the DP transmitter
PN0.6 to PN42 MPa, −200 to +800 °C wetted span
1:3 to 1:10 turndown on the DP transmitter; 50–70 % permanent ΔP loss
- Mechanical primary; pairs with the Rosemount 3051, Yokogawa EJA, or Honeywell ST3000 DP transmitter you already own
- Wet-flow calibrated on the factory loop with ISO 9001 cert and mill cert traceable to heat number
- Conformant with ISO 5167-2 / GB/T 2624-2006; reference-level conventions used in AGA-3 / API 14.3 custody practice
- Out-of-scope: slurry (plugs taps), wet-gas or two-phase (go to Coriolis), turndown above 1:10 (go to vortex / Coriolis / ultrasonic)
Concentric orifice · flange-tap arrangement (ISO 5167-2)
β = d/D, 0.20 to 0.75 · permanent ΔP loss 50 to 70 %; route head-sensitive lines to venturi
The orifice plate is the industry-standard differential-pressure primary element; a precision-bored stainless disc clamped between pipe flanges, conformant with ISO 5167-2 / GB/T 2624-2006. It accepts DN15 to DN6000, PN0.6 to PN42 MPa, and −200 to +800 °C wetted service across clean liquid, gas, steam, and natural gas. A separate DP transmitter (your existing Rosemount 3051, Yokogawa EJA, or Honeywell ST3000; or our ProFlow 3051 on a new line) reads the ΔP signal, performs square-root extraction, and outputs 4-20 mA, HART, or RS-485 proportional to flow. Wet-flow calibrated on the factory loop with ISO 9001 certificate. Ships 5–7 business days; head-sensitive service should go to the venturi counterpart for 10–15 % loss instead of 50–70 %.
Benefits
- DN15 to DN6000 bore range: the only primary on the site that scales from instrument-air branches to power-station main steam and very-large-bore cooling-water headers without changing technology.
- PN0.6 to PN42 MPa pressure rating: highest on the site; covers refinery hot-oil mains, hydrocarbon pipelines, wellhead service, and high-pressure superheated steam where electronic alternatives fail.
- −200 to +800 °C wetted span: cryogenic LN2, LOX, LH2, LNG service through 304/316 SS at the low end; 12CrMo and Cr5Mo chrome-moly for hot oil and superheated steam at the high end.
- Transmitter-flexible: reuse the Rosemount 3051, Yokogawa EJA, or Honeywell ST3000 DP transmitter already on your DCS; the plate is passive and brand-agnostic.
- ISO 5167-2 / GB/T 2624-2006 conformant: discharge coefficient C and expansion factor ε published per geometry; the same standard underwrites AGA-3 / API 14.3 custody practice for natural-gas pipelines.
- Wet-flow calibrated on the factory loop with ISO 9001 calibration certificate and mill cert traceable to heat number on the wetted SS grade.
- Lead time 5–7 business days from the factory, versus the 8–12 weeks typical at premium primary-element vendors.
Configure your build.
Pick bore size, pressure rating, material, flange standard, and tap geometry. The configurator returns the PF-LG-KB model code and a ballpark unit price; engineering replies with a sized β-ratio quote within one business day.
Your Configuration
PF-LG-KB-50-1.6-1-F-FL-Q-N
DN50, PN1.6 MPa, 304 SS, HG/T 20592 flange, flange taps, β factory-sized by quote, primary element only (buyer-supplied DP transmitter).
Estimated unit price
Verified after engineering review
$480
✓ ISO 5167-2 / GB/T 2624-2006 conformant
✓ Wet-flow calibrated, ISO 9001 cert
✓ Reply within 4 business hours
✓ Wet-flow calibrated, ISO 9001 cert
✓ Reply within 4 business hours
Typical applications
Four applications where the orifice plate is the right primary element.
🔥
High-pressure superheated steam main
Power-station and refinery main steam at 10 to 16 MPa and 540 °C. The Cr5Mo or 12CrMo plate sits in service for years where electronic alternatives fail.
💧
Large-bore cooling-water header
Power-station and chemical-plant cooling loops at DN1000 to DN1500. No electronic primary is available at this bore at reasonable cost; the orifice is the workhorse pick.
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Natural-gas custody trunkline
Pipeline custody measurement per ISO 5167 / GB/T 2624 conventions used in AGA-3 / API 14.3 practice. Buyer supplies the smart DP transmitter; we ship the plate and the carrier ring.
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Cryogenic LNG / LH2 retrofit
Cryogenic LN2, LOX, LH2, and LNG service to −200 °C on 304 or 316 SS. Heat-traced impulse lines and a temperature-rated DP transmitter complete the install.
Specifications
| Measurement principle | Differential-pressure primary element; concentric orifice plate creates ΔP proportional to the square of volumetric flow per Bernoulli + continuity; ISO 5167-2 discharge coefficient C and expansion factor ε published per geometry |
|---|---|
| Reference standards | ISO 5167-2 / GB/T 2624-2006 (orifice plates with corner, D-D/2, or flange taps); reference-level conventions used in AGA-3 / API 14.3 natural-gas custody practice |
| Pipe size | DN15 to DN6000 (the broadest of any DP primary; orifice plates are the only DP geometry that scales practically into very-large-bore service) |
| Pressure rating | PN0.6 / 1.0 / 1.6 / 2.5 / 4.0 / 6.4 / 10 / 16 / 25 / 42 MPa (HG/T 20592 flange; ANSI 150 to 1500 lb optional) |
| Medium temperature | −200 to +800 °C (cryogenic LN2 / LOX / LH2 / LNG at the low end; superheated steam and refinery hot oil at the high end) |
| Accuracy (primary) | ±0.5 % of flow on the primary element per ISO 5167; system accuracy also depends on the DP transmitter (typically ±0.075 % URL on a smart HART transmitter) and conformant install |
| Repeatability | ±0.1 % typical per ISO 5167 conformant install |
| Beta ratio | 0.20 to 0.75 per ISO 5167-2; factory-sized by quote from buyer pipe ID, flowing P-T, fluid density, and min/normal/max flow |
| Turndown | 1:3 on a standard 4-20 mA transmitter; 1:7 to 1:10 on a HART smart transmitter with multiple URL ranges; go to Coriolis / vortex / ultrasonic if service exceeds 1:10 |
| Permanent pressure loss | 50 to 70 % of ΔP signal (industry rule for concentric orifice); route head-sensitive service to the venturi element (10–15 % loss) or annubar (negligible) |
| Upstream straight pipe | 22D (single elbow, β=0.5) to 50D (two elbows out-of-plane, β=0.75) per discharge-coefficient chart; 5D downstream |
| Tap geometry | Corner taps / D and D/2 taps / Flange taps per ISO 5167-2; flange taps standard for DN50 to DN600 |
| Wetted material | 304 SS / 316 SS / 316L / 321 SS / 1Cr18Ni9Ti / 12CrMo / Cr5Mo / Hastelloy / Monel / Titanium per medium chemistry and temperature |
| Connection / mounting | Flange HG/T 20592 (PN0.6 to PN42 MPa); ANSI 150 to 1500 lb; threaded NPT for DN15 to DN50 small bore; welded studs for DN1000 and above |
| Applicable media | Clean liquid (water, glycol, hydrocarbon, refined oil, cryogenic LN2/LOX/LH2/LNG); dry gas (air, N2, natural gas, instrument air); saturated and superheated steam; single-phase full-pipe flow only |
| DP transmitter (separate) | ProFlow 3051 / Rosemount 3051 / Yokogawa EJA / Honeywell ST3000 or any 3rd-party HART smart DP transmitter the buyer already owns; primary element ships transmitter-agnostic |
| DP transmitter output | 4-20 mA / HART / RS-485 Modbus (from the DP transmitter; primary element itself is passive, no electronics in the pipe) |
| Hazardous-area cert | CNEX Ex d IIC T6 Gb on the DP transmitter housing (integrated element); the bare plate is passive and requires no Ex certification |
| Ingress protection | IP65 on the DP transmitter housing (integrated element); IP66 / IP67 by special order |
| Calibration | Wet-flow calibrated on the factory loop with ISO 9001 calibration certificate; cert traceable to the national flow standard |
| Lead time | 5–7 business days from factory |
Installation
Five field rules for a conformant ISO 5167 install and a stable ΔP reading.
- 22D upstream / 5D downstream straight pipe minimum Allow at least 22 pipe diameters of straight run upstream of the plate (single elbow, β=0.5) and 5D downstream. Two elbows out-of-plane upstream needs 50D, a regulator or control valve needs 30D or a flow conditioner. Anything less and the velocity profile is undeveloped, the discharge coefficient drifts off ISO 5167, and the reading is biased. The discharge-coefficient chart publishes the L/D requirement by upstream disturbance type.
- Flange-tap orientation horizontal preferred Mount the plate carrier in a horizontal pipe with the tap pair on the side (3 and 9 o'clock) for liquid, on the top (12 o'clock) for gas, and on the bottom (6 o'clock) for steam with condensate-pot drainage. Vertical mount is permitted with flow direction marked on the plate; impulse lines must still slope correctly per medium.
- Impulse lines 8–12 mm OD stainless tubing with continuous slope Route 8 to 12 mm OD SS impulse tubing from each tap to the DP transmitter, with a continuous slope of 1:10 minimum; downward toward the transmitter for liquid service, upward toward the primary for gas service. Total length under 5 m keeps lag inside the loop. Provide isolation valves at the primary and a 3-valve or 5-valve manifold at the transmitter for zero-cal access.
- Heat-trace impulse lines below 0 °C ambient Cold ambient with liquid or condensable gas in the impulse lines freezes the column and zeros the reading. Steam-tracing or electric heat-tracing on the impulse lines is required below 0 °C; the factory does not ship the trace package; buyer responsibility. Same rule applies on cryogenic LN2 / LOX / LH2 / LNG service where the plate handles −200 °C but the lines and transmitter sit at ambient.
- Zero-cal at commissioning with the equalizing valve open Fill the bore with the process medium, stop flow, open the equalizing valve on the manifold to bridge the high-low ports, and run the DP transmitter zero-cal sequence. Record the baseline offset. Close the equalizing valve, open the isolation valves, return to service. Re-zero after the first six weeks once the plate has fully wetted and the impulse lines have de-gassed.
Frequently asked questions
What is an orifice plate flow meter and how does it actually measure flow?+
An orifice plate flow meter is a two-piece instrument: a precision-bored stainless disc clamped between two pipe flanges, plus a separate DP transmitter wired to upstream and downstream impulse-line taps. Fluid accelerating through the bore drops pressure; ΔP scales with the square of volumetric flow per Bernoulli. The transmitter reads ΔP, extracts the square root, and outputs 4-20 mA / HART / RS-485. ISO 5167-2 publishes the discharge coefficient C and expansion factor ε; GB/T 2624 is the Chinese national adoption. Buyer sizes the bore (beta ratio β = d/D, typically 0.20 to 0.75) against operating P-T, fluid density, and transmitter upper range. The plate is passive; no electronics in the pipe, no moving parts.
Does the orifice plate work with my existing Rosemount 3051 / Yokogawa EJA / Honeywell ST3000 transmitter?+
Yes. The plate ships transmitter-agnostic. Reuse any HART smart DP transmitter already in service; Rosemount 3051, Yokogawa EJA, Honeywell ST3000, or ProFlow 3051 on new lines. ISO 5167-2 specifies plate geometry, tap arrangement (corner, D-D/2, or flange), and connections; transmitter brand is independent. Quote the bore size, pressure rating, wetted material, flange standard, and transmitter upper range, and engineering returns a sized β ratio with expected accuracy.
What about turndown, slurry, two-phase flow, and pulsating service?+
Honest constraints. Turndown is capped by transmitter dynamic range and square-root noise floor; typically 1:3 on a 4-20 mA transmitter, 1:7 to 1:10 on a HART smart transmitter. If the service needs greater than 1:10, go to Coriolis (1:200), vortex (1:70), or ultrasonic (1:100). Slurry and particulate-laden flow plug the impulse-line taps; go to electromagnetic. Two-phase or wet-gas degrades the discharge coefficient; go to Coriolis. Pulsating flow needs an accumulator or Coriolis. Cryogenic service is in scope for the plate (304/316 SS to −200 °C) but impulse lines and the DP transmitter need heat-tracing.
What ships with the order, what is the cert, and what is the lead time?+
Lead time is 5 to 7 business days from the factory. Each order ships with the orifice plate stamped with the wet-flow-calibrated K-factor, an ISO 9001 calibration certificate traceable to the national flow standard, a mill cert traceable to heat number for the wetted SS grade, the carrier ring or flange assembly per the order code, and impulse-line tap fittings. ISO 5167-2 / GB/T 2624-2006 are the design-conformance standards the plate is manufactured to; AGA-3 and API 14.3 are reference-level conventions used in natural-gas custody practice. The factory does not ship EU custody-transfer approvals, third-party gas-density equation-of-state backing, or any third-party paper beyond ISO 9001 and the mill cert; buyer-procured if the project requires them. Hazardous-area certification (CNEX Ex d IIC T6 Gb) applies to the DP transmitter housing on the integrated element, not to the bare passive plate.
Need an ISO 5167 primary on a refinery or power-station line?
Send pipe ID, flowing P-T, fluid, min/normal/max flow, max permissible ΔP loss, and the existing DP transmitter brand. Engineering returns a sized β ratio in one business day; lead time 5–7 business days from the factory.