FLD-Nitrogen-Series

Supported Applications

The Omega FLD Series comprises direct read variable area flow meters (rotameters) calibrated for specific gases and liquids. The series is designed for metering carrier gases in chromatography, indicating and controlling gases in manufacturing processes, liquid and gas measurement in laboratories and pilot plants, as well as general flow and level indication.

While the broader FLD family supports Air, Water, Argon, Carbon Dioxide, Helium, Hydrogen, Oxygen, and Nitrogen, this specific series is calibrated for Nitrogen (N2). The instruments feature rib-guided or fluted metering tubes to ensure stable readings.

Operating Conditions & Performance

The FLD Series operates within defined pressure and temperature limits suitable for laboratory and process environments. Key performance specifications include:

• Accuracy: Standard accuracy is plus/minus 5% of full scale (FS).
• Repeatability: Plus/minus 0.25%.
• Useful Flow Range: Minimum 10:1; the minimum flow rate is 10% of the maximum rate shown for a specific model.
• Maximum Operating Pressure: 200 psig/13.8 bars.
• Maximum Operating Temperature: 121 C (250 F).

Note that NIST traceable calibration is not available for this series.

Configuration Options

The Nitrogen-calibrated models are offered in two tube lengths, 65 mm and 150 mm, with a variety of float materials to accommodate different flow ranges. The series supports the following configuration options:

Housing and Mounting

• Frames: Aluminum (black anodized) or 316 stainless steel.
• Mounting Style: Standard panel mount with two retaining nuts supplied; convertible to bench mounting using optional FLTR-1, FLTR-2, or FLTR-3 acrylic tripods with built-in spirit levelers and leveling screws.
• Dimensions (Panel Mount): Drill two 15 mm (0.59 in) holes; maximum panel thickness is 9.5 mm (0.375 in).

Sensor Elements and Wetted Materials

• Floats: Available materials include glass, red sapphire, 316 stainless steel, carboloy, and tantalum.
• Flow Tubes: Heavy walled borosilicate glass with interchangeable tubes for easy exchange.
• O-Rings/Packing: Buna O-rings in aluminum/brass models; FKM O-rings in stainless steel meters. Optional perfluoroelastomer and EPR are available.

Valves and Connections

• Process Connection: 1/8 NPT female inlet and outlet connections.
• Standard Valve: Built-in 6-turn needle valve (inlet mounted standard).
• Valve Options: -NV suffix for units without a valve; -HRV suffix for a 16 turn high resolution non-rising stem metering valve on 150 mm meters.
• Orientation Notes: For liquids, valves may be at inlets or outlets (top); for vacuum services, valves must be mounted at outlets. If unspecified, units ship with valves at the inlet.

Special Service Options

• -02CLEAN: Oxygen cleaning option available.

Key Product Differences

The FLD Nitrogen-Series is distinguished by its specific calibration for N2 and the availability of different frame materials. Models are grouped in ordering tables by tube length (65 mm or 150 mm) and fluid type.

• Float Suffixes: Model numbers indicate float material via suffix: G for glass, ST for 316SS, C for carboloy, and SA for red sapphire.
• Nitrogen Ranges (65 mm): Models such as FLDN3301ST through FLDN3306S cover ranges including 12 L/min down to 6 mL/min and up to 200 mL/min, utilizing a 316 SS frame.
• Nitrogen Ranges (150 mm): Models such as FLDN3501ST through FLDN3506S cover ranges including 1.6 scfm down to 2 L/min and up to 500 mL/min, also utilizing a 316 SS frame.
• No-Valve Variants: Specific SKUs (e.g., FLDN3504C-NV) are available with the -NV suffix for applications requiring no valve assembly.