21128-03-01 | Bently Nevada 1/2-in NPT Velocity Transducer Housing

Solving Harsh Environment Challenges with the 21128-03-01

When a rotating machinery monitoring system must endure hose-directed water, corrosive atmospheres, or physical impacts, the 21128-03-01 from Bently Nevada provides a robust solution. This velocity transducer housing is constructed from 303 stainless steel and designed to meet NEMA 4X and IP65 requirements when properly installed. It ensures that sensitive velocity sensors remain operational in demanding industrial settings, reducing unplanned downtime and maintenance costs.

Key Features & Technical Specs of the 21128-03-01

• Outlet Port Size: 1/2-in NPT for secure cable exit.
• Internal Mounting Thread: 1/2-in 20 UNF for standard velocity sensors.
• Temperature Rating: -29°C to +121°C (-20°F to +250°F), suitable for extreme environments.
• Moisture Protection: Resistant to moisture and corrosion, but not submersible.
• O-ring Material: Neoprene ensures a reliable seal.
• Weight: 1.6 kg (3.55 lb) without sensor or fittings, easy to handle.
• Mounting Thread and Cap Option: 03 = 1/2-in 14 NPT for versatile installation.

One distinctive spec is the wide temperature range of -29°C to +121°C, which allows the housing to perform reliably in both freezing outdoor environments and high-temperature process areas. This eliminates the need for separate enclosures in many applications.

Real-World Applications for the 21128-03-01

In petrochemical plants, refineries, and power generation facilities, the 21128-03-01 is commonly used to house velocity transducers that monitor vibration on pumps, compressors, and turbines. Its corrosion-resistant 303 stainless steel construction withstands chemical splashes and washdowns. Because it meets IP65 requirements, it is ideal for outdoor installations exposed to rain and dust. The housing also protects sensors from accidental physical contact, ensuring consistent data collection.

Installation Guide for the 21128-03-01

Mount the housing using the 1/2-in 20 UNF internal thread for the velocity sensor. For cable exit, use the 1/2-in NPT plug provided with the 01 cable exit fitting option. Ensure the neoprene O-ring is properly seated to maintain the IP65 seal. When installing a Velomitor CT sensor, the tall cap option is required. Similarly, if using a 9200 or 74712 Seismoprobe with an isolated base, the tall cap option is necessary. For non-hazardous environments, the standard 21128 housing is preferred; for explosive atmospheres, use the CA21128 version with CSA certification.

Maintenance & Reliability Tips

Periodically inspect the neoprene O-ring for cracks or deformation to maintain the moisture seal. Check the mounting threads for corrosion or galling, especially in harsh chemical environments. The 303 stainless steel construction resists rust, but regular cleaning with a damp cloth is recommended to remove surface contaminants. Because the housing is not submersible, avoid prolonged immersion. Following these simple steps extends the service life of both the housing and the velocity sensor, reducing total cost of ownership.

Frequently Asked Questions about the 21128-03-01

Q: What is the temperature rating of the 21128-03-01?

A: The housing is rated for -29°C to +121°C (-20°F to +250°F).

Q: Is the 21128-03-01 submersible?

A: No, it is resistant to moisture and corrosion but is not submersible.

Q: What cable part number is needed to connect a Velomitor sensor to a monitor using this housing?

A: Cable part number 89477-AA is necessary for that connection.

Q: Can the 21128-03-01 be used in hazardous areas?

A: The standard 21128 is for non-hazardous environments. For explosive atmospheres, use the CA21128 explosion-proof version.

Product Support & Availability

The 21128-03-01 is in stock and ready to ship from Petro Auto Tech. Please verify current lifecycle status and availability with Petro Auto Tech before ordering.