21000-28-05-00-105-04-02 Bently Nevada Proximity Probe Housing

Overview

The 21000-28-05-00-105-04-02 is an API 670 compliant, explosion-proof proximity probe housing assembly engineered by Bently Nevada. Designed for hostile industrial machinery environments, this assembly provides sealed enclosure protection for reverse-mount 3300 XL 8 mm proximity probes used in continuous vibration, shaft position, and axial displacement monitoring systems.

Constructed from die-cast aluminum with a 304 stainless steel sleeve, the 21000-28-05-00-105-04-02 modular housing allows external probe penetration adjustments without removing main machine casing covers. It carries CSA Type 4 ratings and intrinsically safe approvals for Class I, Division 1 and 2 hazardous locations.

Configuration Breakdown: 21000-28-05-00-105-04-02

• Base Housing Model: 21000 — Aluminum Body with 304 Stainless Steel Sleeve
  • [28] Probe Option: 3300 XL 8 mm Reverse Mount Probe (Hazardous Area Approved)
    • [05] Cable Length: 0.5 meter (20 inches) Miniature Coaxial Cable
  • [00] Standoff Adapter: No Standoff Adapter Included (Direct NPT Mounting)
    • [105] Probe Penetration Depth: 10.5 inches (266.7 mm) Sleeve Length
  • [04] Fitting Option: One 3/4-14 NPT Conduit Plug Installed
    • [02] Mounting Thread Option: 3/4-14 NPT External Process Connection Thread

Engineering Specifications & Structural Parameters

Cross-Model Specification Comparison & Technical Selection

Selection Engineering Guidance:

• System Generation Matching: Select the target unit based on your Proximitor sensor architecture. Option 28 (3300 XL) delivers linear extended scale performance and enhanced EMI immunity compared to legacy Option 16 (3300) transducers.
• Mechanical Clearance Calculations: Option 00 provides direct surface thread engagement for deep machine insertion (10.5 in). If external clearance between the machine wall and structural steel is constrained, select models with standoff adapters such as the 21000-16-05-15-072-03-02 to offset the outer dome housing.

Target Machinery & Industrial Field Applications

• API 612 Steam Turbines: Thrust position and radial vibration tracking on high-pressure casing glands.
• Centrifugal Gas Compressors: Shaft displacement surveillance on high-speed hydrocarbon barrel compressors.
• Boiler Feed Pumps: Continuous axial rotor position feedback under high ambient humidity and temperature cycling.
• Induced Draft Fans & Blowers: Machinery protection loops operating in Class I, Division 1 hazardous process gas areas.

Diagnostic Integration & Mechanical Integrity

• Internal sleeve design protects delicate coaxial cable runs against physical abrasion, oil saturation, and flying mechanical debris.
• Adjustable reverse-mount probe threaded sleeve permits precise target gap setting (typically -9.00 VDC or 1.0 mm baseline gap) prior to sealing the outer dome cover.
• O-ring body seal structure retains CSA Type 4 isolation, preventing moisture ingress into the conduit header during high-pressure washdown cycles.
• Compatible with TK-3 3-Channel optical gap verification tools and digital voltmeters connected to 3300 XL Proximitor sensor diagnostic terminals.

Global PLC Spare HUB's Insight

In high-vibration machinery installations, incorrect installation of the 21000 sleeve center-lock nut can lead to false thrust displacement trip alarms. The probe sleeve must be rigid within the machine shell tap; any axial play in the 304 stainless steel tube will mimic rotor movement to the 3300 XL eddy current sensor, shifting the DC gap voltage outside the calibrated -9.00 VDC baseline window.

During an overhaul on an offshore compressor deck, field technicians reported erratic vibration spikes on a 10.5-inch sleeve assembly. Diagnostic analysis using a dial indicator showed that thermal expansion on the long unguided 10.5-inch sleeve caused mechanical resonance at operating speeds. Installing a midpoint dampening bushing and re-torquing the 3/4-14 NPT thread seal restored mechanical stability, eliminating false vibration signals and maintaining continuous 24/7 protection.

Logistics, Delivery & Warranty Policy

• Factory Quality: Supplied as 100% genuine Bently Nevada hardware in original factory packaging.
• Warranty Assurance: Backed by a full 12-month factory-grade replacement warranty starting from dispatch date.
• Express Global Courier: Worldwide expedited priority shipment handled via FedEx, UPS, and DHL Express.
• Dispatch Lead Time: Factory inventory items ship within 24 to 48 hours following order confirmation.

Engineering Selection FAQ

How is the total probe sleeve penetration calculated when ordering a 21000 housing assembly?

Measure the distance from the outer surface of the machine mounting boss to the target shaft face, factoring in required probe gap clearance. Match this total depth directly to the suffix code (e.g., 105 represents 10.5 inches of internal penetration).

Can a 3300 XL probe with a 0.5-meter cable be extended directly to a remote monitor cabinet?

No, the 0.5-meter probe cable must connect to a matching 3300 XL extension cable and 3300 XL Proximitor sensor. The total combined length of probe plus extension cable must equal exactly 5.0 meters or 9.0 meters according to Proximitor tuning.

What is the primary benefit of selecting an aluminum body housing over stainless steel options?

The aluminum body (21000) provides lightweight structural protection and superior heat dissipation at a lower cost, suitable for standard API 670 installations. Stainless steel housings (24701) are recommended primarily for highly corrosive marine environments.

How do technicians reset probe gap voltage without disassembling the entire housing body?

Unscrew the outer dome cover, loosen the internal sleeve lock nut, and rotate the reverse-mount sleeve assembly using precision hand tools while monitoring the Proximitor output DC voltage until the target voltage (e.g., -9.00 VDC) is reached.

What maintenance procedure should be followed when replacing an internal probe in a hazardous zone?

Ensure loop power to the Proximitor sensor is isolated or verify the area is non-hazardous. Remove the housing dome cover, disconnect theClickLoc coaxial connector, loosen the sleeve retaining nut, and back out the reverse-mount probe without disturbing main process piping.

Tags