21128 and 42608 Velocity Transducer
Housings
Datasheet

Bently Nevada Machinery Condition Monitoring

141628 Rev. H

Description
Velocity Transducer Housings protect velocity sensors fromdamage caused by hose-directed water, corrosion, physicalabuse, or other adverse environmental conditions.
Constructed of 303 stainless steel, these housings aredesigned to meet NEMA 4X and IP65 requirements whenproperly installed.
The 21128 housing is preferred for most non-hazardous
environmental conditions. The CA21128 is the explosion-proof
version that is CSA certified for use in Classes I, II, and III,Division 1, Groups B, C, D, E, F, and G. It must be ordered andshipped with a CSA approved velocity sensor installed in theassembly. The BA42608 housing is used for BASEEFAapproved installations where compliance with BS EN 60079 14
is necessary. It provides the environmental and physicalprotection needed to comply with the IP65 rating defined in
IEC standard 144.
Each of these housings is now available with a tall cap. The
tall cap option is required if the customer wants to install aVelomitor CT in a housing. The tall cap option is also required
if installing either a 9200 or 74712 Seismoprobe with anisolated base into the 21128 housing.

21128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. H

Specifications
PhysicalOutlet PortSize

1/2-in NPTInternal Mounting Thread
21128 andCA21128

1/2-in 20 UNF

BA42608

5/8-in 18 UNF-2B

Weight

1.6 kg (3.55 lb) without velocity
sensor or fittings

Environmental
Temperature-29°C to +121°C (-20 °F to +250°F)
RatingMoisture

Resistant to moisture and corrosion
but is not submersible

O-ringMaterialNeoprene

2/821128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. H

Compliance andCertifications
FCC
This device complies with part 15 of theFCC Rules. Operation is subject to thefollowing two conditions:llThis device may not cause harmfulinterference.
This device must accept any
interference received, includinginterference that may cause
undesired operation.

RoHS
RoHS Directive 2011/65/EU

3/8

21128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. H

Explosion-proof Velocity
Transducer Housing including
Transducer

Ordering Information
For the detailed listing of country and productspecific approvals, refer to the Approvals Quick
Reference Guide (108M1756) available from
Bently.com.

CA21128 - AA-BB-CC-DD
B00 Transducer Mounting Angle/Minimum
Operating Frequency option is applicable toA00 and A01 Transducer Type Options. The
others are applicable to the A04 Transducer
Type Option.

Water and Corrosion-resistant
Velocity Transducer Housing

A: Transducer Type Option

21128 - AA-BB
Compatible with all Bently Nevada velocity
sensors having 1/2-in 20 UNF mounting
threads and a top mount connector. If
planning to install the Velomitor CT or9200/74712 sensors with an isolated base,
you must order one of the ‘tall cap’ options.
A: Mounting Thread and Cap Option
01

Unthreaded base, 28.5 mm (1.125 in)diameter

02

00

No Transducer

01

Includes 330500 Velomitor velocity sensor,
datasheet 141632

04

Includes 9200 Seismoprobe velocity
sensor, datasheet 141626

05

Includes 74712 Seismoprobe velocity
sensor, datasheet 141626

B: Transducer Mounting Angle/Minimum
Operating Frequency Option:
00

No option

3/4-in 14 NPT

31

0 ±2.5, 4.5 Hz (270 cpm)

03

1/2-in 14 NPT

32

45 ±2.5, 4.5 Hz (270 cpm)

04

1/2-in 14 BSP (G 1/2-in)

33

90 ±2.5, 4.5 Hz (270 cpm)

11

Unthreaded base, 28.5 mm (1.125 in)diameter with tall cap

36

0 ±100, 10 Hz (600 cpm)

12

3/4-in 14 NPT with tall cap

39

0 ±180, 15 Hz (900 cpm)

13

1/2-in 14 NPT with tall cap

C: Mounting Thread and Cap Option

14

1/2-in 14 BSP (G 1/2-in) with tall cap

01

Unthreaded base, 28.5 mm (1.125 in)diameter

B: Cable Exit Fitting Option

02

3/4-in 14 NPT

01

1/2-in NPT plug03

1/2-in 14 NPT

02

1/2-in NPT, explosion-proof fitting

04

1/2-in 14 BSP (G 1/2-in)

03

1/2-in NPT, explosion-proof and cablegrip fittings

11

Unthreaded base, 28.5 mm (1.125 in)diameter with tall cap

12

3/4-in 14 NPT with tall cap

13

1/2-in 14 NPT with tall cap

14

1/2-in 14 BSP (G 1/2-in) with tall cap

D: Cable Exit Fitting Option

4/8

01

1/2-in NPT plug02

1/2-in NPT, explosion-proof fitting

03

1/2-in NPT, explosion-proof and cable gripfittings

21128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. HIP65 Water and Dust-resistant
Velocity Transducer Housing
BA42608 - AA-BB
If this housing is used with 9200 or 74712
velocity sensors, the sensors must have ATeXor Multiple approvals and an isolator having
5/8-in 18 UNF-2B male threads and a top
mount terminal strip.
A: Mounting Thread and Cap Option
01

Unthreaded base, 28.5 mm (1.125 in)diameter02

3/4-in 14 NPT

03

1/2-in 14 NPT

04

1/2-in 14 BSP (G 1/2-in)

11

Unthreaded base, 28.5 mm (1.125 in)diameter with tall cap

12

3/4-in 14 NPT with tall cap

13

1/2-in 14 NPT with tall cap

14

1/2-in 14 BSP (G 1/2-in) with tall cap

B: Cable Exit Fitting Option
01

1/2-in NPT plug02

1/2-in NPT, explosion-proof fitting

03

1/2-in NPT, explosion-proof and cable grip
fittings

5/8

21128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. H

Graphs and Figures

Figure 1: Velocity Transducer Housing with Tall Cap
Dimensions are in millimeters (inches).

6/8

21128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. H

Figure 2: Velocity Transducer Housing with Standard Cap

7/8

21128 and 42608 Velocity Transducer Housings
Datasheet

141628 Rev. H

Copyright 2020 Baker Hughes Company. All rights reserved.

Bently Nevada, Orbit Logo, Seismoprobe and Velomitor are registered trademarks of Bently Nevada, a Baker Hughes
Business, in the United States and other countries. The Baker Hughes logo is a trademark of Baker Hughes
Company. All other product and company names are trademarks of their respective holders. Use of the trademarks
does not imply any affiliation with or endorsement by the respective holders.
Baker Hughes provides this information on an “as is” basis for general information purposes. Baker Hughes does
not make any representation as to the accuracy or completeness of the information and makes no warranties ofany kind, specific, implied or oral, to the fullest extent permissible by law, including those of merchantability andfitness for a particular purpose or use. Baker Hughes hereby disclaims any and all liability for any direct, indirect,
consequential or special damages, claims for lost profits, or third party claims arising from the use of theinformation, whether a claim is asserted in contract, tort, or otherwise. Baker Hughes reserves the right to makechanges in specifications and features shown herein, or discontinue the product described at any time without
notice or obligation. Contact your Baker Hughes representative for the most current information.
The information contained in this document is the property of Baker Hughes and its affiliates; and is subject tochange without prior notice. It is being supplied as a service to our customers and may not be altered or its content
repackaged without the express written consent of Baker Hughes. This product or associated products may becovered by one or more patents. See Bently.com/legal.

1631 Bently Parkway South, Minden, Nevada USA 89423
Phone: 1.775.782.3611 or 1.800.227.5514 (US only)
Bently.com

8/8