21128-11-02 | Bently Nevada -29°C to +121°C Velocity Transducer Housing

What Is the 21128-11-02?

When harsh environmental conditions threaten sensor integrity, the 21128-11-02 from Bently Nevada provides robust protection. This velocity transducer housing is constructed from 303 stainless steel, designed to shield velocity sensors from hose-directed water, corrosion, physical abuse, and other adverse conditions. Properly installed, it meets NEMA 4X and IP65 requirements, making it a reliable choice for non-hazardous locations.

With a temperature rating of -29°C to +121°C (-20°F to +250°F), this housing ensures consistent performance across extreme thermal environments. Its unthreaded base with a 28.5 mm (1.125 in) diameter and tall cap accommodates Velomitor CT sensors, as well as 9200 or 74712 Seismoprobe models with isolated bases.

Key Features & Technical Specs

• Material: 303 stainless steel for corrosion resistance.
• Temperature Rating: -29°C to +121°C (-20°F to +250°F).
• Moisture Protection: Resistant to moisture and corrosion but not submersible.
• O-ring Material: Neoprene for reliable sealing.
• Weight: 1.6 kg (3.55 lb) without sensor or fittings.
• Outlet Port Size: 1/2-in NPT explosion-proof fitting.
• Internal Mounting Thread: 1/2-in 20 UNF for 21128 and CA21128 models.

The distinctive spec here is the tall cap option, which is required for installing Velomitor CT sensors or Seismoprobe sensors with isolated bases. This design flexibility ensures compatibility with key sensor types without additional adapters.

Applications & Use Cases

Industries such as oil and gas, power generation, and water treatment benefit from the 21128-11-02 housing. For example, in a refinery where hose-down cleaning is routine, this housing prevents water ingress and corrosion, extending sensor life. Similarly, in outdoor turbine monitoring, the -29°C to +121°C range allows reliable operation in freezing winters and hot summers. By choosing this housing, engineers reduce replacement costs and downtime associated with sensor damage.

Installation Guide

Mount the 21128-11-02 using the 1/2-in 20 UNF internal thread for standard installations. For the BA42608 model, use the 5/8-in 18 UNF-2B thread. Ensure the outlet port is fitted with a 1/2-in NPT explosion-proof fitting for hazardous area compliance. When using the 21128 Housing, cable part number 89477-AA is necessary to connect the Velomitor Sensor to a monitor. Always follow Bently Nevada's installation manual for torque specifications and sealing requirements.

Maintenance & Reliability

Regularly inspect the neoprene O-ring for cracks or wear to maintain the IP65 seal. Clean the housing exterior with a damp cloth—avoid abrasive cleaners that could damage the stainless steel finish. Because the housing is not submersible, ensure it is installed above potential flood levels. This simple maintenance routine maximizes the housing's service life and protects your sensor investment.

Compatible Systems

The 21128-11-02 is designed for Bently Nevada velocity transducers such as the Velomitor CT, 9200 Seismoprobe, and 74712 Seismoprobe with isolated base. It requires cable part number 89477-AA for sensor-to-monitor connection. For integration with monitoring systems, refer to Bently Nevada's compatibility documentation.

Common Questions About the 21128-11-02

Q: What is the temperature range of the 21128-11-02?

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

Q: Is the 21128-11-02 submersible?

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

Q: What material is the O-ring made of?

A: The O-ring material is neoprene.

Q: What is the weight of the housing?

A: It weighs 1.6 kg (3.55 lb) without sensor or fittings.

Q: What cable is needed for the Velomitor sensor?

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

Product Support & Availability

The 21128-11-02 is in stock and ready to ship from Petro Auto Tech. Contact our team for pricing and lead times. We are your trusted source for Bently Nevada industrial automation parts.