Brüel & Kjær VS-069 Vibration Velocity Sensor

The Brüel & Kjær VS-069 is the vertical-direction member of the standard Brüel & Kjær Vibro velocity sensor pair for permanent installation. It offers the same operating range of -40 to +80 °C, a 5 m open-end cable and a steel protective conduit as the VS-068, but its measurement direction is vertical. It is an electrodynamic sensor, so it produces its own signal without any supply voltage.

Vertical velocity sensing on machine casings

Use the VS-069 where the vibration of interest acts up and down, for example on the top of a bearing housing or a machine foot where the sensor stands on a horizontal surface. The measuring element is a coil on springs inside a permanent magnet field; when the casing moves, the coil moves relative to the field and induces a voltage proportional to velocity. The sensor measures absolute casing and bearing vibration in the range 10 Hz to 2000 Hz, or 1 Hz to 2000 Hz when the monitor applies linearization, and its natural frequency is 8 Hz ±10 %.

The stainless-steel housing is hermetically sealed and rated IP 66. The manual includes a separate admissible mounting range for vertical and horizontal versions, so check the drawing in the manual before fixing the sensor at an inclined point.

Technical specifications

Values below are taken from the Brüel & Kjær Vibro velocity sensor brochure (May 2024) and the VS-068 / 069 / 077 / 079 instruction manual (V10).

Cable protection and installation notes

The connection is an integrated 5 m shielded PTFE cable, 2 x 0.14 mm², 3.3 mm diameter, with open wire ends; the manual states that it can be extended to a maximum of 200 m via a terminal box. Signal polarity is stated for the white wire: a positive signal appears there for the bearing movement direction drawn in the manual. A steel conduit with PU sheath (11.5 mm outside diameter, 17 mm fitting, M12 x 1.5 thread) protects the cable, and the brochure installation example pairs the sensor with the AC-2104/0 junction box and AC-112 signal cable.

Fixing is by the central M10 thread. Fit the M10 x 25 mm stud 15 mm deep in the machine, secure it with a thread-locking agent and tighten the sensor to 14 Nm, or 7.1 Nm with the M10 x M8 adapter. The sensor and cable must not be loaded by the laid conduit during operation, because forces in the sensor system can corrupt the measuring result.

VS-069 compared with the other standard codes

All sensors below are listed in the brochure for permanent installation or Ex-area use.

If both directions are needed from one sensor, the brochure lists the VS-077. The VS-069 carries no hazardous-area approval; the VS-0169 is the Ex-area counterpart with its own marking, a 10 m cable without protective conduit and a narrower temperature range.

Typical measuring points for the VS-069

Vibration velocity in mm/s is the measure that ISO 20816 (formerly ISO 10816) applies to bearing housings and other non-rotating parts, so the VS-069 signal can be compared directly with the severity zones used in most maintenance programmes. The vertical version suits measuring points where the sensor sits on a flat horizontal face: the top cap of a pump or motor bearing housing, the bearing pedestal of a fan, or the foot and base frame of a machine where looseness or soft-foot problems show up as vertical vibration. Vertical-shaft pumps and agitators are another case where the sensor orientation needs to follow the actual direction of movement.

Many users install the VS-069 together with the horizontal VS-068 at the same bearing so that both radial directions are covered with matched sensitivity of 100 mV/mm/s. The sensor is passive, so no loop supply has to be routed to the machine. When fitting it, check the admissible inclination range in the manual, keep the steel conduit supported so that it does not load the sensor, verify signal polarity on the white wire, and log a baseline value at normal operating load as the reference for later trend alarms.

Documents and quotation

The official Brüel & Kjær Vibro velocity sensors brochure (English, 05/2024) is attached to this page and lists the order codes, electrical data, cable designs and dimensions. The brochure states that all data are non-binding, so confirm the exact order code, direction and cable arrangement against the current manufacturer documents before ordering. Seven Star LLC is an independent supplier based in Muscat and supplies this sensor on request with the quotation and the technical documents; no price is shown on this page. Related items are listed under Vibration Monitoring.