What the 21000 Assembly Is Designed to Do

The Bently Nevada 21000 is an all-metal housing assembly for externally mounted proximity probes. Its aluminum body uses a 304 stainless steel sleeve. Available elements include a dome cover, conduit ports, O-rings, thread sealing, a reverse-mount probe, fittings and a standoff adapter, supporting protected machine-case installation.

How to Read the Ordering Structure

The official format is 21000-AA-BB-CC-DDD-EE-FF. The AA field identifies the probe and connector choice, BB specifies probe-cable length, CC defines the optional standoff-adapter dimension, DDD records probe penetration, EE selects the fitting package and FF identifies the mounting thread. This structure explains why visually similar assemblies should not be treated as interchangeable. Procurement and maintenance teams should compare the entire code with the installed nameplate, drawing and probe system.

Where the Housing Fits

The series is intended for external proximity-probe mounting on machinery. It is relevant to instrumentation, reliability and maintenance teams working with shaft vibration or position measurement points that require a protected machine-case installation. The official data describes CSA Type 4 enclosure compliance and API 670 compliance for externally mounted housings, but hazardous-area approval depends on the exact housing and option combination. Approval markings and the destination country should therefore be checked rather than assumed from the family name.

Installation and Maintenance Checks

The probe lead must exceed the sleeve length. Combined standoff and penetration above 12 inches requires sleeve support near the probe. Penetration from 1.0 to 2.0 inches may require a machine-case counterbore. During maintenance, preserve the mounting thread, fittings and probe family, then inspect the full label before choosing a spare.

When to Review a Newer Housing Family

For a new installation where an explosion-proof housing is not required, Bently Nevada recommends reviewing the newer 31000/32000 housing family, which provides more flexible mounting options and improved environmental resistance. This does not make it an automatic replacement for an installed 21000 assembly. Mechanical dimensions, probe choice, approvals and mounting details still require project-level verification.

Recommended Bently Nevada Models

Before ordering, confirm model, approvals, cable length, dimensions, fittings, thread, quantity and label. Links appear only for verified StockOEMs product pages.

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