FLD-Hydrogen-Series

Supported Applications

The Omega FLD Series comprises direct read variable area flow meters (rotameters) designed for the metering of gases and liquids. The series is explicitly documented for use with Air, Water, Nitrogen (N2), Hydrogen (H2), Carbon Dioxide (CO2), Argon (Ar), Helium (He), and Oxygen (O2). Documented applications include metering carrier gases in chromatography, indicating and controlling gases in manufacturing processes, liquid and gas measurement in laboratories and pilot plants, as well as flow and level indication.

Operating Conditions & Performance

The FLD Series operates with a maximum operating pressure of 200 psig/13.8 bars and a maximum operating temperature of 121 C (250 F). Standard accuracy is specified as plus/minus 5% of full scale (FS), with repeatability at plus/minus 0.25%. The useful flow range provides a minimum ratio of 10:1, where the minimum flow rate is defined as 10% of the maximum rate shown for each specific model.

For Hydrogen service specifically, available ranges include:

• 65 mm tubes (316 SS Frame): Maximum flows from 1.5 L/min to 42 L/min and 35 mL/min to 600 mL/min.
• 150 mm tubes (316 SS Frame): Maximum flows of 225 scfh and 100 mL/min.

Note that NIST traceable calibration is not available for this series. The meters are shipped completely assembled with mounting fittings, side plates, a protective magnifying front shield, back plate, built-in control valve, and flow tubes.

Configuration Options

The FLD Series offers configurable dimensions across tube lengths of 65 mm or 150 mm. Frames are available in aluminum (black anodized) or 316 stainless steel construction. The series supports various wetted materials and float types to accommodate different media requirements.

Construction Materials

• Flow Tubes: Heavy walled borosilicate glass with rib-guided or fluted designs for stable readings.
• Floats: Options include glass, red sapphire, 316 stainless steel, carboloy, and tantalum. Suffixes denote float material: G (glass), ST (316SS), C (carboloy), SA (red sapphire).
• Mounting Fittings: Aluminum (black anodized) or 316 stainless steel.
• O-Rings and Packing: Buna O-rings in aluminum/brass models; FKM O-rings in stainless steel meters. Optional perfluoroelastomer and EPR are available.

Housing & Mounting

• Sides Panels: Aluminum, black anodized.
• Front Shield: Polycarbonate resin with a longitudinal magnifier lens for enhanced reading resolution.
• Back Plate: 1/8 in thick white acrylics.
• Mounting Options: Standard panel mount (drill two 15 mm holes; maximum panel thickness 9.5 mm) or convertible to bench mounting using optional FLTR-1, FLTR-2, or FLTR-3 acrylic tripods with built-in spirit levelers.

Valve & Connection Options

• Process Connections: 1/8 NPT female inlet and outlet connections.
• Standard Valve: Built-in 6-turn needle valve. Inlet mounting is standard; for liquids, valves may be at inlets or outlets (top); for vacuum services, valves must be mounted at outlets.
• Valve Options:-NV suffix provides a unit without valve; -HRV suffix adds a 16-turn high resolution non-rising stem metering valve (available on 150 mm meters).

Key Product Differences

The series is organized by fluid type, tube length, and frame material. Model numbers follow the pattern FLD[fluid letters][4-digit tube/size/range number][float suffix][options]. For example, FLDA denotes Air, FLDW Water, FLDH Hydrogen, etc.

Key distinctions within the series include:

• Tube Lengths: 65 mm and 150 mm options affect maximum flow capacity and physical dimensions (e.g., inlet/outlet center distance is 114 mm for 65 mm size, 224 mm for 150 mm size).
• Frame Material: Aluminum frames are available for many gas applications; stainless steel frames are required or offered for specific fluids like Hydrogen (FLDH), Helium (FLDHE), and Oxygen (FLDO) in the documented variants.
• Oxygen Cleaning:-02CLEAN suffix indicates oxygen cleaning is performed on the unit at additional cost.