281.491.2331 13839 West Bellfort Street Sugar Land, Texas
281.491.2331 13839 West Bellfort Street Sugar Land, Texas
ISO 9001:2015
U.S. Patents
90 + U.S. Patents
Since 1954
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Where to Use

  • Downstream of turbine meters or rotary meters to protect against high gas velocities and rotor over-speeding
  • Anywhere it is necessary to limit capacity, maintain clean flow, and minimize pressure loss

Enforcing the Speed Limit

The Welker FLN Flow Limiting Nozzle puts the brakes on rotor over-speeding to protect your turbine or rotary meter from damage and preserve its accuracy.

Install the FLN downstream of your meter between two raised face flanges to protect against high gas velocities that can occur when pressurizing and blowing down the pipeline and during times of high demand. The FLN helps develop the flow profile of the gas after limiting flow, reducing turbulence and minimizing pressure loss. Each FLN is custom designed for your meter and application, so you can be assured your meter will run within its normal working range.

Data SheetFLN Data Sheet
Over Range Protection
Stop Running Your Meter Ragged

Proven Over-Range Protection

Over-speeding your meter may be permissible for short durations, but why run the risk? Operating a meter outside of its normal working range can damage the measuring mechanism, negatively affecting the meter’s accuracy and your bottom line. The FLN provides proven cost-effective meter protection. That means less maintenance, more useable gas, and more revenue!

Funneled Flow

High Recovery Design

Unlike an orifice plate, the FLN does not create an abrupt restriction or create a permanent pressure loss. With a convergent inlet, short throat, and divergent outlet, the FLN contains and controls the expanding flow to reduce pressure and turbulence. This high recovery design limits the amount of wasted energy so there is minimal pressure loss in the system.

High Recovery Design
Make of it What You Will

Tailor to Your Needs

One inch or eight? High pressure or low pressure? Carbon steel or stainless steel? Standard insertion or reverse insertion? Welker customizes every FLN to your meter make and model and process conditions for optimal protection.

Don't Lose Your Bearings

Additional Meter Protection

The FLN provides excellent over-range protection for your meter. For added meter protection and process automation, install a Welker Oiler. The Oiler automatically delivers a small fixed volume of lubricant to prevent bearing burnout.

The Oiler


FLN Flow Limiting Nozzle
Materials of ConstructionCarbon Steel (Standard) or 316/316L Stainless Steel
Pipeline ConnectionSize: 1", 2", 3", 4", 5", 6", 8", or 12"

Rating: 150, 300, or 600 ANSI RF
FeaturesLifting Eyebolt (for 8" and 12")
Stud Bolts and Nuts