Flow Nozzle (ISO 5167 Long Radius)

Although a flow nozzle costs more than an orifice because of its construction, it is suitable for measuring the flow of fluids at high temperature and high pressure.
Under the same measuring conditions, a flow nozzle has higher mechanical strength, can pass more than 60% more flow than an orifice of the same bore, and measures fluids containing solid particles with less disturbance than an orifice. It is therefore also suitable for high-velocity fluids.
Supplied not only as a nozzle alone but also as a meter run with short pipe sections welded on both the upstream and downstream sides.
The Flow nozzles, more costly than other orifice due to their structure, are suited for determining the flow rates of fluids flowing at high temperature and high pressure. Under the same measuring conditions, a flow nozzle has a higher mechanical strength, can permit the flow of more than 60 percent greater volume of a fluid, and can measure the flow rates of fluids containing solid particles less disturbed, than an orifice having the same bore. Thus, they are suited, in addition, for highspeed flowing fluids. We can supply not single flow nozzles, but also flow nozzles having welded short pipes on both their upstream and downstream sides.
Differential-pressure structure and flow relationship

The long radius nozzle consists of an elliptical (quarter-ellipse) convergent section and a cylindrical throat of length 0.6d, with differential pressure sensed at taps located 1D upstream and 1/2D downstream (1D-1/2D taps).
Depending on β (= d/D), nozzles are classified as high ratio (0.25 ≤ β ≤ 0.8) or low ratio (0.2 ≤ β ≤ 0.5), and their shapes differ.
Specification comparison by model



The three images are cutaway renderings with the pipe cut lengthwise to show the installation method; the actual products are closed pipe / meter-run sections.

| Item | DHON-BW Weld-in type (Weld in) | DHON-HR Holding ring type (Holding Ring) | DHON-FL Flanged type |
|---|---|---|---|
| Features | Butt welding mounting type (Weld in type, FIG 1) | Holding ring mounting type (Holding Ring type, FIG 2) | Flange mounting type (Flange type, FIG 3) |
| Turndown | 6:1 | 6:1 | 6:1 |
| Materials | Carbon Steel, STS304, STS316, Inconel, Monel, Hastelloy | Carbon Steel, STS304, STS316, Inconel, Monel, Hastelloy | Carbon Steel, STS304, STS316, Inconel, Monel, Hastelloy |
| Connection | Butt Weld | Butt Weld | Flange 150#, 300#, 600#, 900#, 1500#, 2500# |
| Applicable piping | 2B ~ 24B (50A ~ 600A) Pipe | 2B ~ 24B (50A ~ 600A) Pipe | 2B ~ 24B (50A ~ 600A) Pipe |
| Standards | ISO5167-3 | ISO5167-3 | ISO5167-3 |
| Accuracy | ±2.0% | ±2.0% | ±2.0% |
Detailed conditions are confirmed at quotation.
| Item | Value |
|---|---|
| Accuracy | ±2.0% |
| Turndown | 6:1 |
| Mounting type | ISO 5167 Long Radius — Weld in type (FIG 1) · Holding Ring type (FIG 2) · Flange type (FIG 3) |
| Flow calculation standard | ISO5167, JIS Z 8762, ASME, KS A 0612 |
| Pressure taps | 1D - 1/2D taps |
| Applicable pipe sizes | 2 to 24B (50A to 600A) |
| β range | 0.2 ≤ β ≤ 0.8 — Low beta long radius nozzle 0.2 ≤ β ≤ 0.5 · High beta long radius nozzle 0.25 ≤ β ≤ 0.8 |
| Nozzle material | Carbon Steel · 304SS, 304L SS, 316SS, 316L SS · Ni, Cr, Mo Alloy Steel (A182 F11 to 91) |
| Meter run material | A53 Gr B · A106 Gr B · A335 P11 · A335 P22 · A335 P51 · A335 P91 |
| Flange rating | 150#, 300#, 600#, 900#, 1500#, 2500# (DHON-FL) |
| DP tap connection | NPT 1/2 · NPT 3/4 · SW 1/2 · SW 3/4 |
| Holding ring type meter run | Upstream 4D (MIN.) · downstream 2D (MIN.) · reducer angle 30° Max · splice weld required to maintain the minimum downstream length per A.S.M.E. Fluid Meters |
| Weld-in type note | For sizes under 3", the downstream connection weld may overlap the nozzle/pipe weld |
Straight run and installation notes
You can request a quotation by combining the model codes.
| BW | Weld in type |
| HR | Holding Ring type |
| FL | Flange type |
| N | Element Only (nozzle only) |
| Y | Meter run Include (meter run included) |
| □□□ | Pipe size in inch or mm (nominal pipe size, inch or mm) |
| A1 | A105 |
| 4S | A182 F304 |
| 4L | A182 F304L |
| 6S | A182 F316 |
| 6L | A182 F316L |
| 11 | A182 F11 |
| 22 | A182 F22 |
| 51 | A182 F51 |
| 91 | A182 F91 |
| OP | Option |
| A5 | A 53 Gr B |
| 10 | A 106 Gr B |
| P1 | A 335 P11 |
| P2 | A 335 P22 |
| P5 | A 335 P51 |
| P9 | A 335 P91 |
| 00 | Option |
| 1 | NPT 1/2 |
| 2 | NPT 3/4 |
| 3 | SW 1/2 |
| 4 | SW 3/4 |
| 000 | Flange Rating (specify flange rating) |
| /□□□ | Options (by separate agreement) |
Product Catalog PDF
Printable datasheet with the specifications, dimensions and ordering information on this page (same content as the web page, generated automatically)
ISO 5167 long radius nozzle (DHON) catalog — description · specifications · nozzle shape · FIG 1~3 · ordering codes · 3 pages
p.14 Flow Nozzle DHON-BW / HR / FL· 23p
Other models in the same product family
Tell us the pipe size, fluid, pressure / temperature and flow range, and we will propose a suitable model and a flow calculation sheet.
Contact us online ✉ [email protected] (Sales)Tel 031-357-8431 (Sales, ext. 1) · Fax 031-357-8432