Insertion Vortex Flow Meter

No shutdown is required for the meter install itself; that is the core appeal of a hot tap flow meter over a flanged in-line unit. The workflow has three steps: (1) Your piping contractor welds a 1″, 1.5″, or 2″ threaded boss onto the live main and installs a ball valve on top. (2) A hot-tap cutter makes the hole through the valve, the cutter is removed, and the valve is closed. (3) Our insertion probe threads into the ball valve, the valve is reopened, and the probe is pushed to its calibrated depth. Total line-side downtime is zero.

Insertion flow meter accuracy lands at ±1.5% under good flow-profile conditions; the structural ceiling for any point-velocity probe on an insertion type flow meter. The LUGB is a point-velocity measurement multiplied by a pipe-geometry K-factor; full-bore in-line meters integrate velocity across the whole cross-section and reach ±1.0%. Insertion meets ±1.5% with straight pipe upstream and fully turbulent flow. The trade-off pays off for sub-measurement, allocation, and trend monitoring on lines too large for an in-line build. Custody transfer and regulatory billing still require an in-line model.

Three situations. (1) Large diameter; a DN600 in-line vortex runs around $8,000 plus freight and flange-pair install; an insertion probe for the same line is $1,200 and pays for itself in reduced logistics alone. (2) Retrofit with no shutdown window; if the plant cannot stop the gas main or steam header, insertion is the only option. (3) Sub-metering many big pipes; ten in-line meters at DN400+ is a capital project; ten insertion probes is a maintenance-budget item. Below DN150 or for custody-transfer accuracy, stay with the in-line model.

A retractable insertion meter has a compression packing gland and a safety chain. You can retract the probe fully back into the ball valve while the line is live, close the ball valve behind it, and remove the probe for cleaning or replacement without stopping the process. Useful when the meter might foul (biogas, flue gas with particulate), when you expect to swap between duty and standby, or when plant rules mandate live maintenance. For clean compressed air or natural gas the fixed version is sufficient and about 35% cheaper.

The probe bluff body sits at 1/8 of the pipe ID from the wall; that’s the Chebyshev point where local velocity equals the cross-sectional average for a fully-developed turbulent profile. Measure your pipe ID (not OD), enter it in the configurator, and we pre-set the insertion depth marking on the probe shaft. The probe shaft is long enough to cover DN1200 in the standard length and DN2000 in the long-shaft option. For non-round ducts (stacks, rectangular flue runs) the formula changes; talk to us at quote stage.

Any single-phase clean gas, dry steam, or light-particulate flue gas. We’ve built it into: compressed air mains, natural gas distribution, saturated and superheated steam, nitrogen blanket systems, CO₂ headers, argon, and coal-plant flue gas ducts. Liquids are out-of-scope; vortex meters are poor at liquid service below certain Reynolds numbers and insertion vortex even more so. Heavy particulate (cement plant raw-gas, kiln exhaust) will erode the bluff body; for those use a thermal mass or Averaging Pitot tube with abrasion-resistant coating instead.

Four trigger conditions push you from insertion to LUGB-VRd. (1) Accuracy: you need ±0.5% of reading instead of ±1.5%. The LUGB-VRd integrates velocity across the whole cross-section with built-in T+P compensation for true Nm³/h. (2) Turndown: insertion gives roughly 1:15–1:20; LUGB-VRd holds the full 1:70 at ±0.5%. (3) Custody transfer: insertion is never acceptable for billing; the point-velocity × K-factor method is not recognized by metrology authorities. (4) Line size DN150 or smaller: the flanged LUGB-VRd costs barely more than insertion plus hot-tap labour at that scale, and the insertion probe series itself starts at DN200.

Both share the same upstream-straight-pipe discipline; ≥10D upstream and ≥5D downstream of the bluff body, growing to 25D upstream after a 90° elbow. The difference is how the sensor enters the line. A flanged vortex flow meter installation requires cutting the pipe and bolting a new spool between flange pairs, so you schedule a shutdown. An insertion flow meter installation uses a 1″–2″ threaded boss plus ball valve welded onto the live pipe, so the process keeps running. Our configurator locks the Chebyshev 1/8-ID insertion depth before it generates the model code.

The LUGB insertion type flow meter handles gas, dry steam, and clean single-phase media; compressed air, natural gas, oxygen, nitrogen, hydrogen, and saturated or superheated steam. Insertion electromagnetic probes need conductive liquid and do not read gas. Insertion ultrasonic probes target clean liquids. Insertion turbine probes carry moving parts and require recalibration. The insertion type vortex flow meter sheds Karman vortices off a bluff body sampled at the Chebyshev 1/8-ID point, which is why the LUGB-VRd build; 2024 China Instrument Society Top-10; anchors this application at ±1.5% reading accuracy.