21128-12-01 | Bently Nevada 3/4-in NPT Velocity Transducer Housing

Introduction to the 21128-12-01 Bently Nevada Velocity Transducer Housing

When harsh environmental conditions threaten the reliability of your velocity sensors, the 21128-12-01 from Bently Nevada provides a robust solution. This housing is constructed from 303 stainless steel and meets NEMA 4X and IP65 requirements when properly installed. It is designed to protect sensors from hose-directed water, corrosion, physical abuse, and other adverse conditions. The 21128-12-01 is preferred for most non-hazardous applications, making it a versatile choice for industrial monitoring.

Key Features and Technical Specifications

• Mounting Thread and Cap: 3/4-in 14 NPT with tall cap
• Cable Exit Fitting: 1/2-in NPT plug
• Temperature Rating: -29°C to +121°C (-20°F to +250°F)
• Moisture Resistance: Resistant to moisture and corrosion but not submersible
• O-ring Material: Neoprene
• Weight: 1.6 kg (3.55 lb) without sensor or fittings
• Internal Mounting Thread: 1/2-in 20 UNF (for 21128 and CA21128)
• Outlet Port Size: 1/2-in NPT

The tall cap option is required for installing a Velomitor CT or a 9200 or 74712 Seismoprobe with an isolated base. This housing also requires cable part number 89477-AA to connect the Velomitor Sensor to a monitor.

Applications and Use Cases

In industrial settings where sensors face moisture, corrosion, or physical impact, the 21128-12-01 delivers reliable protection. It is ideal for use in manufacturing plants, oil and gas facilities, and water treatment operations. The housing ensures that velocity transducers remain operational in environments with hose-directed water or corrosive atmospheres. Additionally, its NEMA 4X and IP65 ratings make it suitable for outdoor installations where weather resistance is critical.

Installation and Setup

Installing the 21128-12-01 involves mounting the housing using the 3/4-in 14 NPT thread and securing the cable exit with the 1/2-in NPT plug. Ensure the O-ring is properly seated to maintain the IP65 seal. For Velomitor CT or Seismoprobe installations, use the tall cap option. Always follow Bently Nevada guidelines to achieve the specified environmental protection.

Maintenance and Reliability

Regular inspection of the O-ring and housing seals helps maintain moisture resistance. The 303 stainless steel construction resists corrosion, extending service life in demanding conditions. Periodic checks for physical damage or wear ensure continued protection. The neoprene O-ring should be replaced if any deterioration is noticed to preserve the IP65 rating.

Compatibility and Integration

The 21128-12-01 is compatible with Bently Nevada velocity sensors such as the Velomitor CT, 9200 Seismoprobe, and 74712 Seismoprobe. It requires cable part number 89477-AA for Velomitor sensor connections. The housing fits standard 1/2-in NPT cable fittings and uses a 1/2-in 20 UNF internal mounting thread for 21128 and CA21128 models.

Troubleshooting and Common Issues

If moisture enters the housing, check the O-ring for damage or improper seating. Ensure the cable exit plug is tightened correctly. For sensor connection issues, verify that cable 89477-AA is used and properly terminated. If the housing does not meet IP65 requirements, inspect all seals and threads for wear.

FAQ about the 21128-12-01

Q: What is the temperature rating of the 21128-12-01?

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

Q: Is the 21128-12-01 submersible?

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

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

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

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

A: The O-ring material is neoprene.

Q: What is the weight of the 21128-12-01 without sensor?

A: The weight is 1.6 kg (3.55 lb) without velocity sensor or fittings.

Product Support and Availability

The 21128-12-01 is in stock and ready to ship from Petro Auto Tech. Contact our team for pricing and availability. We provide fast delivery and reliable support for your industrial automation needs.

Customer Case Scenario

In a chemical processing plant, velocity sensors monitoring pump vibrations were failing due to corrosive fumes. By installing the 21128-12-01 housing, the sensors were protected from corrosion and moisture, reducing replacement costs and improving uptime. This illustration shows how the housing extends sensor life in challenging environments.