21128-04-02 | Bently Nevada 1/2-in NPT Velocity Transducer Housing

How the 21128-04-02 Prevents Sensor Damage in Harsh Environments

When velocity sensors face hose-directed water, corrosive chemicals, or physical impact, the 21128-04-02 provides robust protection. Constructed from 303 stainless steel, this Bently Nevada housing meets NEMA 4X and IP65 requirements when properly installed. It resists moisture and corrosion but is not submersible, making it ideal for non-hazardous locations where environmental threats are present.

Key Features & Technical Specs of the 21128-04-02

• Mounting Thread and Cap Option: 04 = 1/2-in 14 BSP (G 1/2-in).
• Cable Exit Fitting: 02 = 1/2-in NPT explosion-proof fitting.
• Temperature Rating: -29°C to +121°C (-20°F to +250°F).
• O-ring Material: Neoprene for reliable sealing.
• Weight: 1.6 kg (3.55 lb) without sensor or fittings.
• Internal Mounting Thread: 1/2-in 20 UNF for 21128 and CA21128 models.
• Outlet Port Size: 1/2-in NPT.

The 21128-04-02 includes a tall cap option required for installing a Velomitor CT or a 9200/74712 Seismoprobe with isolated base. When using this housing with a Velomitor sensor, cable part number 89477-AA is necessary to connect to a monitor.

Applications & Use Cases for the 21128-04-02

This housing is preferred for most non-hazardous environmental conditions where sensors need protection from water jets, corrosive atmospheres, or mechanical abuse. Typical applications include rotating machinery monitoring in oil and gas, power generation, and pulp and paper industries. The 21128-04-02 ensures reliable vibration measurement by shielding velocity transducers from external damage.

Installation Guide for the 21128-04-02

Proper installation is critical to maintain NEMA 4X and IP65 ratings. Mount the housing using the 1/2-in 14 BSP thread and secure the cable exit with the 1/2-in NPT explosion-proof fitting. Ensure the O-ring is seated correctly to prevent moisture ingress. For tall cap configurations, verify clearance for the sensor assembly. Always follow Bently Nevada's installation manual for torque specifications.

Maintenance & Reliability of the 21128-04-02

Regular inspection of the O-ring and cable fitting prevents seal degradation. The 303 stainless steel construction resists corrosion, extending service life in wet environments. Periodically check for physical damage or debris around the housing. Because the housing is not submersible, avoid immersion in liquids. Following these steps reduces downtime and replacement costs.

Compatibility & Integration

The 21128-04-02 housing is designed for Bently Nevada velocity transducers. It requires cable 89477-AA for Velomitor sensor connections. The internal mounting thread (1/2-in 20 UNF) fits standard sensor bases. The tall cap option accommodates Velomitor CT and Seismoprobe models with isolated bases. Verify sensor dimensions before ordering.

FAQ about the 21128-04-02

Q: What is the temperature rating of the 21128-04-02?

A: The temperature rating is -29°C to +121°C (-20°F to +250°F).

Q: Is the 21128-04-02 submersible?

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

Q: What cable is needed for a Velomitor sensor in this housing?

A: Cable part number 89477-AA is necessary to connect the Velomitor sensor to a monitor.

Q: What is the weight of the 21128-04-02?

A: The housing weighs 1.6 kg (3.55 lb) without the velocity sensor or fittings.

Product Support & Availability

The Bently Nevada 21128-04-02 is available from Petro Auto Tech. Contact our team for current lead times and ordering assistance. We stock genuine Bently Nevada parts to support your industrial automation needs.