Series-NF401

Supported Applications

Weiss Instruments Series NF401 leakproof pressure gauges are stainless steel cased, liquid-filled industrial instruments designed for severe applications involving vibration, corrosion, and pulsating conditions. The product overview identifies suitability for agricultural equipment, hydraulic systems, oil field equipment, pumps, compressors, and car wash systems.

Operating Conditions & Performance

The series supports pressure ranges from vacuum to 15,000 psi across various model configurations. Accuracy varies by case size and construction: ±1.6% of span for the LF251/LF252/NF252 models; 1% of span for LF441/LF442/NF402 models; and 1/2% of span for LF602/NF602 models.

Process connections are provided as 1/4" NPT bottom or center back. Wetted materials include Phosphor Bronze, Type 316 Stainless Steel, Brass, and Type 316 S.S., depending on the specific series model. The standard filling medium is Glycerine (rated +20°F to +150°F), with Silicone available as a special order for -40°F/150°F service.

A warning in the documentation notes that misuse may cause explosion and personal injury, advising users to read ANSI B40.1 before installation or use. It further states that Glycerine can combine with strong oxidizing agents including chlorine, nitric acid, and hydrogen peroxide to result in an explosion.

Configuration Options

The series is offered in 2 1/2", 4", and 6" case sizes. Housing materials include Type 304 stainless steel with polished stainless steel crimped or bayonet rings, depending on the model.

• Case Sizes: 2 1/2" (Series LF251/LF252/NF252), 4" (Series LF441/LF442/NF402), and 6" (Series LF602/NF602).
• Mounting Options: Direct mounting, wall or panel mounting. Specific configurations include U-Clamp (e.g., Series LF251U/LF252U), Front Flange (e.g., Series LF251F/LF442F), and Back Flange (e.g., Series NF602BF).
• Window Materials: Clear acrylic, Safety glass, or Tempered Glass depending on the series.
• Dial Markings: psi & kPa markings are available on specific models such as LF251/LF252/NF252 and NF402.

Key Product Differences

The series distinguishes between liquid-filled (LF) and non-liquid filled or industrial stainless steel case variants. The 6" models feature a bayonet ring, while the 2 1/2" crimped ring cases utilize Type 304 stainless steel with Phosphor Bronze tubes up to 6000 psi for LF251.

Specific model differences include:

• Series LF251/LF252/NF252 (2 1/2"): Ranges extend from vacuum, compound, and pressure to 6000 psi or 10,000 psi. Tubes are Phosphor Bronze for LF251 up to 6000 psi; Type 316 Stainless Steel is used for higher ranges in other models.
• Series LF441/LF442/NF402 (4"): Ranges extend from vacuum, compound, and pressure to 5,000 psi or 15,000 psi. The NF602 model includes a blow out disc.
• Series LF602/NF602 (6"): Features Type 316 stainless steel tubes and sockets with threaded restrictors; ranges extend to vacuum, compound, and pressure up to 15,000 psi.