Bruel & kjaer 2513 User manual

InstructionManual

Integrating Vibration Meters Types 2513 and 2516

8n,ll&Kjoof'

...

Type2513

A pair

of

ultra-compact

all solid-state Vibra-

tion Meters

for

measuring Vibration Sever-

ity,

Hand-Arm

Vibration and wide-band

vi-

brations between 10

Hz

and 10 kHz. The

thermometer-type

display reads vibration

velocity

or

acceleration

In

two

selectable 1-

to-100 ranges, with a choice

of

RMS,

Max-

RMS, Peak, and Peak/60 s Leq indications.

The engineering-units graduations are met-

ric on the 2513, and

g's/inches-per-second

on the 2516. An AC output socket permits

connection

of

a recorder or analyzer.

+

BrUel

&

Kjcer

INTEGRATING VIBRATION METERS

TYPES 2513 and 2516

2513

from

serial

number

842642

2516

from

serial

number

1033687

January

1986

This apparatus has been designed and tested according

to

IEC Publication 348, Safety

Requirements

for

Electronic Measuring Apparatus, and has been supplied in safe

condi-

tion. The present Instruction Manual contains

information

and warnings which should be

followed by the user

to

ensure safe operation and to retain the apparatus in safe

condi-

tion.

CONTENTS

1.

INTRODUCTION AND SPECIFICATIONS {PRODUCT DATA) .............................................................................. 1

2.

CQNTROLS..................................................................................................................................................................5

3.

OPERATION .................................................................................................................................................................8

3.1. INTRODUCTION .....................................................................................................................8

3.2. BATTERY INSTALLATION......................................................................................................8

3.3. MOUNTING THE 2513 AND 2516.........................................................................................9

3.4. CONNECTING

UP

AND MOUNTING THE ACCELEROMETER......................................10

3.5. TAKING A VIBRATION MEASUREMENT...........................................................................

11

3.6. FURTHER CONSIDERATIONS FOR HAND-ARM MEASUREMENTS............................ 12

3.7. DETERMINATION OF CREST FACTOR .............................................................................14

4.

USE WITH OTHER INSTRUMENTS........................................................................................................................16

4.1. PORTABLE GRAPHIC LEVEL RECORDER ......................................................................16

4.2. SERIAL FREQUENCY ANALYSIS USING A FILTER AND A LEVEL RECORDER........ 17

4.3. REAL-TIME FREQUENCY ANALYSIS ................................................................................19

4.4. MAGNETIC TAPE RECORDING .........................................................................................19

5.

SERVICE AND REPAIR.............................................................................................................................................

21

USES:

• Measurement of machine condition for mainte-

nance procedures

• Vibration Severity measurements

of

rotating and

reciprocating machinery

• Production quality control

• Occupational health investigations

of

powered

hand-tools

• Vibration and shock testing

• General vibration measurements

for

design, re-

search and development work

FEATURES:

• Choice

of

measurement units -

SI

with 2513,

g's

and

in/s

with 2516

• Robust, slim-line construction

• Compact pre-calibrated Piezoelectric Accelerom-

eter, with robust connection-cable, supplied

The

Types

2513

and

2516 Integrating

Vibration Meters have been developed

to

meet

the

needs of

the

user who re-

quires

an

economical

yet

accurate in-

strument

for day-to-day vibration mea-

surements. Compact

and

light enough

to

be carried

in

the

Document Folder

supplied,

they

incorporate several ad-

vanced features which enable

them

to

be used easily by busy personnel for

whom mechanical vibration measure-

ment

is only one ofmany activities.

The

2513 is graduated in metric units,

and

the

2516 in g's

and

in/s.

Fig.I. Documentation

of

measurements

taken on site with the Vibration Me-

ter in its folder

BP

0078-13

types 2513

and

2516

Integrating Vibration Meters

• True Peak, Max-Peak, RMS

or

RMS-Max. indica-

tion

of

vibration acceleration

or

velocity

• Vibration acceleration ranges cover 1 to

1000

m/s

2 (2513), 0,1 to 100g (2516)

• Vibration velocity ranges cover 0,1 to 100

mm/s

(2513), 0,01 to 10

in/s

(2516)

• Electronic integration of measurement for one-

minute

Leq

display (equivalent-energy level)

selectable

• Solid-state thermometer-type read-out covers

100:1 range

• Measures Hand-Arm vibration (to ISO/DP 5349

with Charge Attenuator available to order

or

alter-

native Accelerometer), Vibration Severity (to ISO

2954), or wide-band vibration

10

Hz

to 10kHz

• AC output for use with recorder, analyzer etc.

• Low-energy circuits for long battery life

$,uel

•

Kl••

~

Type

2613

·;

•

-

:-:}.

-

:-'

.

..

Typo2616

The

2513

and

2516

are

intended

for

four main kinds of application -

General

vibration

measure-

ments.

Vibration measurements are

valuable in many branches

of

industry.

Some examples of applications are:

shock measurement in rolling mills, leak

detection in pipes,

and

pulsation mea-

surements

in

pneumatic

and

hydraulic

systems. Fields of use include power

generation, mining, motor vehicles,

ships,

and

railways.

Condition

monitoring.

It

is

well

known

that

most kinds

of

machinery

failures are preceded by a rise in vibra-

tion level. Regular measurement of ma-

chine vibration level can be used

to

de-

cide whether

the

machine requires

maintenance. This can form

the

basis of

a systematic

and

economical

technique

The

Types

2513

and

2516

are

com-

pact

battery-powered

instruments

easily held

and

operated

in

one hand.

The

2513

measures

in

SI

units,

and

the

2516

in

g's

and

in/s. A

document

folder designed

to

contain

both

the

Vibration

Meter

and

an

A4

note-pad

--

,..,

Adaptor

I

UA

0641

Accelerometer

Ilia

Type

4384

•

Magnet..,_

UA

0642

-

Ferromagnetic

Disc YO

0070

Plug

JP

0213

l

tO

.t

•

l(jar

......

Type

211•

Fig.2.

The

interconnection arrangements

for the 2513

and

2516 (illustrated)

2

for scheduling maintenance.

It

is appli-

cable

to

a very wide range

of

industrial

plant, including machine-tools, steel,

board

and

paper

mills, chemical plants,

cement ovens, compressors, diesel en-

gines,

and

power stations.

Vibration

Severity

measure-

ments.

Vibration Severity is a

quantity

particularly useful in

the

evaluation of

the

running quality

of

rotating

and

re-

ciprocating machinery.

The

2513

and

2516 meet

the

requirements for

an

in-

strument

suitable for measuring Vibra-

tion Severity as laid down in ISO 2954

(1975). Vibration Severity criteria are

covered by ISO 2372, 2373

and

3945,

and corresponding national standards.

For quality-assurance personnel

and

technical

staff

engaged in buying or sell-

ing machinery,

the

2513

and

2516 pro-

vi~e ideal means of checking

that

the

for recording

measurements

taken

on

site is also

included

(Fig.l).

Each

Vi-

bration

Meter

is

supplied

with

a light-

weight Piezoelectric Accelerometer

Type

4384,

connected

to

the

instru-

ment

by a

sturdy

1,2 m coaxial cable

(see Fig.2).

Display

The

2513

and

2516

feature

a solid-

state

thermometer-type

display which

makes

them

especially easy

to

use

without

sacrificing accuracy.

It

con-

sists of a

column

of

41

red

light-emit-

ting

diodes (LEDs) covering a relative

amplitude

range of 1

to

100.

The

am-

plitudes

are

spaced

out

logarithmical-

ly,

thus

giving a

constant

accuracy

over

the

whole range.

The

LEDs, how-

ever,

are

equally spaced, so each suc-

cessive

LED

corresponds

to

an

ampli-

tude

11

%

greater

than

the

one below

it.

If

the

amplitude

measured

falls be-

tween

two

LEDs,

they

are

both

lit,

giving a resolution

of

6%.

The

display range

itself

can

be

switched

between

two

settings

differ-

ing

in

level by a factor

of

10, giving

an

overall

measurement

range

of

1000:1.

The

Leq

Concept

Anyone who has

tried

to

measure vibra-

tion with a conventional

instrument

will

have had

the

experience where

the

me-

ter

fluctuates so much

that

a kind of

visual average has

to

be

made of suc-

cessive readings.

It

is difficult

to

sustain

confidence in

the

validity ofsuch a mea-

surement,

and

in any case

the

"true"

level of such a fluctuating vibration

is

not

the

same

as

the

average reading.

What is needed is

an

indication of the

level which would have resulted in

the

same vibrational energy flow

at

the

measuring point, over a suitable period

of

time, as

the

fluctuating vibration

which actually occurred. This level is

widely known as

Leq

(for "Equivalent

Level").

vibration generated by a machine in op-

eration meets its contractual require-

ments. Because of

their

simplicity

of

op-

eration, only

the

briefest of introduc-

tions is needed before

the

user

starts

making accurate measurements with

the

2513 or 2516.

Hand-Arm

Vibration.

Of particu-

lar concern

to

manufacturers

and

users

of

portable power tools, and environ-

mental

health

authorities, are

the

ef-

fects of sustained exposure

to

vibration

transmitted

into

the

hands

and

arms of

their

operators.

The

2513

and

the

2516

incorporate

an

electronic weighting fil-

ter

to

permit measurements

to

.be made

of

the

overall level

of

exposure, in accor-

dance with

ISO/DP

5349 (Draft

1982-02-17) when used with a Charge

Attenuator available

to

order or a suit-

able alternative Accelerometer.

The

main

graduation

levels are

framed

in

"windows",

and

change

automatically

with

function setting. A

scale of decibel (dB)

graduations

is

provided in

addition

to

the

engineer-

ing-units scale.

The

60

s

Leq

facility

on

the

2513

and

2516

takes

the

vagueness

out

of

vibra-

tion

measurement

when

the

level is

fluctuating.

In

this

mode

of

operation,

the

display builds

up

an

indication

of

the

60s

Leq,

computed

by

mathemati-

cal

integration

from all

the

mean

square

levels occurring since

the

mea-

surement

started

(hence

the

name

"Integrating

Vibration

Meter").

At

the

end

of 60 s

the

measurement

is

termi-

nated

and

the

display

held

for a fur-

ther

60s.

After

that

the

instrument

is

automatically

switched off,

to

save

batteries.

The

operator

can

thus

write

down a single figure for

the

vibration

measurement,

with

complete confi-

dence

that

it

is a

repeatable

figure.

When

the

Leq

function is selected,

the

display simultaneously indicates

the

maximum

peak

value.

In

effect,

it

becomes two displays.

There

is no pos-

sibility of

ambiguity

because

the

max-

imum

peak

vibration

can

never be less

than

the

Leq

value (Fig.3).

Vel. &I I

-

SO

Reset

(Battl

f!'."'3-:

::--

30

•

On/Off

•

Fig.3.

The

display

of

the 2513, showing

Leq

and·Max. Peak indications simulta-

neously

The

display

can

also be

set

to

read

running

peak

levels only,

with

1s de-

cay-time

constant,

and

RMS

values,

with a 1s

time

constant.

Either

instan-

taneous

or

maximum

RMS

indication

may

be selected.

All

the

display functions

are

avail-

able

with

a choice

of

indication

of

vi-

bration

acceleration

or

velocity. ·

The

preferred

parameter

depends

on

the

application.

Three

different

weight-

ings

may

be

selected

-

Linear,

Sever-

ity

and

Hand-Arm.

The

display

flashes

if

an

overload occurs,

and

the

level

indication

is

suppressed

until

the

overload is removed,

to

help

avoid

false

measurements.

The

display

can

also be

set

to

indicate

battery

condition.

Vibration

Transducer

The

Type

4384 Piezoelectric Accel-

erometer

supplied

with

the

2513

and

2516 is

of

Delta-Shear

®

construction,

and

is

trimmed

during

manufacture

to

achieve a

Uni-Gain

® sensitivity

of

1pC

per

m/s

2•

This

ensures

inter-

changeability

between

all 2513/2516's

and

4384'

s,

and

eliminates

the

need

for sensitivity

adjustment

of

the

Vi-

bration

Meter

by

the

user.

Calibration

of

the

overall

measuring

system

(4384

plus 2513/2516) is

not

normally

neces-

sary,

but

it

can

be

checked

using

the

Type

4291

or

4294 Accelerometer Cal-

ibrator

(not

included).

The

extended

frequency

response

of

the

2513/2516

measuring

system

(Fig.4) is

of

advantage

where

vibra

-

tions

to

be

measured

are

caused by

cavitation,

turbulence,

roller-bearing

defects, etc.

The

phase

response

has

also

been

optimized

for

accurate

shock

measurement.

The

Mounting

Magnet

UA 0642

supplied

with

the

Accelerom-

eter

is

designed

to

exploit

the

full fre-

quency

range

of

the

2513/2516 system.

A disc

made

of

self-adhesive

PTFE

(2

supplied)

may

be

placed

under

the

Magnet

if

electrical isolation

of

the

Accelerometer from

the

mounting

sur-

face is

required.

Ferromagnetic

Ce-

menting

Discs YO 0070, like

the

one

supplied

with

the

Magnet,

may

be

glued

to

regular

measuring

positions,

using epoxy resin

or

cyanoacrylate

ad

-

hesive,

and

left

permanently

in

place.

Alternatively

the

Accelerometer

can

be

mounted

directly

by

a

Threaded

Stud

(supplied)

in

a

tapped

hole

in

the

mounting

object.

To

connect

the

Accelerometer

to

the

Vibration

Meter,

a

sturdy

Cable

AO 0193,

designed

to

withstand

the

co

(I)

~

-10------1----~""'--i--

-+-'~="-"::---+--\------;x0

,3

~

(I)

en

C

0

C.

~

-20

(I)

>

~

tolerances)

0

C.

en

~

-+-,R,c,-----+---""1r-'----+--'-+------;x0,1

~

ai

a:

~

-30!----,..f',---f-------1-------.~---jf---..:;.,_

.+-----11-----,----1,------1x

0,

03

Un

,.___...._

___

I--

_____

I--

____

----IIL-L""'-=......L-~=----------'xo,01

10

100

1 k

10k

Frequency

(Hz) 100 k

821300

Fig.4.

Th

e fre

qu

ency r

es

ponse

we

ig

htin

gs

of

th

e 2513

and

2516 (ex

cludin

g Accelerometer).

Th

e re

spon

se for

Hand-Arm

weig

htin

g

appli

es

to vibration ac

ce

leration (se

v.

and

Lin

.

dB

s r

e.

1

nm/

s,

Hand-Arm

dB

s r

e.

I

µm

/,

,

;2)

Integrating

Vibration

Meter

2513

or

2516

Portable Graphic

Level Recorder

2317

801209/2

Fig.

5.

Measurement

and

analysi

s

systems

which

ma

y

be

built

round

the

2513 or 2516

rigours

of

regular shop-floor use, is

provided.

This

Cable is

suitable

for

use over a wide

temperature

range

(-74°

to

+180°C),

and

generates

neg-

ligible

internal

noise.

It

is

terminated

with

robust

TNC

coaxial connectors.

Connection

to

the

Accelerometer is via

an

Adaptor,

UA 0641, which incorpo-

rates

a seal

to

provide good

mechani-

cal

contact

and

moisture-resistance.

The

Accelerometer

may

alternatively

be

used

with

a

standard

Accelerome-

ter

Cable (AO 0038,

supplied)

and

Adaptor

JP

0162 (available as

an

ac-

cessory) for

measurements

on

light

-

weight

structures.

A

number

of

alternative

Accelerom-

eters

are available from

B&K

for vari-

ous

applications

.

In

particular,

for

Hand-Arm

measurements

to

ISO/DP

5349 (1982-02-17),

"Hand-Arm"

Transducer

Set

Type

4392 is recom-

mended

for

the

2513 (with some small

correction for Accelerometer sensitiv-

ity tolerance).

This

set

comprises a

miniature

Accelerometer

Type

4374

and

two

adaptors

which overcome

the

problem

of

the

transducer

interfering

with

the

operator's

grip. Alternatively,

for

the

2516,

the

Miniature

Acceler-

ometer

Type

4375 is available or, for

both

2513 & 2516,

the

Accelerometer

Type

4384

supplied

can

be

used

to-

gether

with

an

optional

Charge

Atten-

uator.

Use

with

Other

Instruments

Fig.5 shows a

number

of

other

B &K

instruments

which

may

be

used

to

ex-

tend

the

applications

of

the

2513 or

2516.

The

AC

Output

of

the

Vibration

Meter

may

be

connected

to a

Portable

Level

Recorder

Type

2317

to

generate

graphic

hard-copy

recordings

of

vibra-

tion

level over a period of time, such

as

during

machine

run-up

and

shut-

down.

The

addition

to

this

combina-

tion

of a

Tunable

Band

Pass

Filter

Type

1621, which

can

be synchronized

with

the

recorder,

permits

serial fre-

quency analysis of vibration.

However, for r~gular

vibration

anal-

ysis, use

of

the

2513

or

2516 with

the

Portable

Tape

Recorder

Type

7005

(which includes FM recording facili-

ties

for good phase-response) is rec-

ommended.

The

recordings can

then

be

played

back

through

a Real

Time

Analyzer,

such

as

Type

2031, 2032,

2033, 2034

or

2131.

Frequency

analysis

gives

an

extra

dimension

to

the

inves-

tigation

of

mechanical vibrations,

and

extends

the

scope

of

machine

condi-

tion

monitoring

to

failure prediction.

3

Specifications 2513 and 2516

MEASUREMENT AMPLITUDE RANGES:

2513 Selectable Ranges: 1

to

100

and

10

to

1000m/s

2

acceleration;

0,1

to

10

and

1

to

100

mm/

s

velocity

2516 Selectable Ranges:

0,1

to

10

and

1

to

100g

acceleration;

0,01

to

1

and

0,1

to

10in/s

velocity

Hand-Arm Range (2513

and

2516): 100

to

160

dB

re 10-6

m/s

2 when

used

with

a

suitable

Charge

Attenuator

or

alternative

Acceler

-

ometer

Maximum Internal Noise: 2513: 0,2

m/s

2

ac-

celeration,

o,

1

mm/s

velocity;

2516: 0,02 g

ac-

celeration,

0,007

in/s

velocity

MEASUREMENT FREQUENCY RANGES:

Lin:

10Hz

to

10kHz

±

3dB

(tolerance

at

high

-

er

frequencies

In

this

range

is

dependent

on

good

mounting

of

Accelerometer)

Sev:

10Hz

to

1kHz,

to

ISO 2954 (1975)

H-A: 8 Hz

to

1kHz,

to

ISO

DIP

5349

(Draft

1982-02-17)

INDICATION:

Level Indicated:

Instantaneous

or

Maximum

True

Root-Mean-

Square

(RMS),

with

1s

time

constant

True

Peak,

with

1s

decay-time

constant

60s Leq

simultaneously

with

Maximum

Peak

Overall Accuracy:

(at

80 Hz) ±

6%

(including

Accelerometer

sensitivity

tolerance).

Tem-

perature

sensitivity

± 0,05

dB/°

C.

Vibration

sensitivity

-20

dB

(relative

to

the

vibration

level

at

the

Accelerometer).

Magnetic

sensi-

tivity

negligible

for

field

strengths

up

to

100

Alm

Shock Measurement Accuracy:

(with

half-

sine

impulse)

+2

-3

dB

for

0,1

to

5

ms

Im-

pulse, ± 1

dB

for

0,5

to

2

ms

Impulse.

RMS Crest-Factor: 3

for

full

scale

indication,

worst

case, 100

at

3%

of

full

scale

RMS Max. Droop: Held

Indication

will

fall

by

not

more

than

6%

of

indication

per

minute

Peak Rise-Time: 6%

per

µS.

For

a

rectangu-

lar

step, 60

µ.s

Leq/Max.-Peak function:

Display

gives

two

simultaneous

Indications.

Lower

Is 60s

Leq,

upper

Is

Max.-Peak.

Display

flashes

until

MEASUREMENT CHARACTERISTICS:

Sensitivity: 1

pC

per

m/s

2 ±

2%

{10pC/g)

Capacitance: 1,2nF

approx.

(Incl. 1,2m

ca-

ble).

Actual

value

given

on

calibration

chart

Mounted reaonance: 35

kHz

(threaded-stud)

Transverse aenaltivity:

Max

. 4%

of

main-

axis

sensitivity.

Orientation

of

minimum

sen-

sitivity

marked

on

case

Piezoelectric material: PZ23

Base-strain aenaltivity:

Typically

0,02

m/s

2

(0,002

g)

per

µStrain

(measured

In

base

plane

.at 250µ.Straln

to

ANSI

S2.11-1969)

Temperature transient aenaltivity:

Typically

0,8m/s~

per

00

(0;044g

per

°F)

(to

ANSI

S2.11-1969)

Magnetic aenaitlvlty:

Typically

7

m/s

2

per

T

(0,07g

per

k Gauss),

measured

at

50

Hz

and

0,03T

'

measurement

terminated

after

60s ± 2%;

then

display

held

for

further

60s

Display:

41-element

LED

"thermometer"

style

Brightness Adiustment:

Automatic

compen-

sation

for

ambient

lighting

by

photo-sensitive

transistor

Resolution: 6% (0,5dB).

Intermediate

levels

are

signified

by

Illumination

of

2

adjacent

LEDs

Scales:

Engineering

units

(m/s

2

and

mm/s

on

2513,

g's

and

in/s

on

2516)

with

logarithmic

graduations,

plus

dB

re 1

µm/s

2

and

1

nm/s

(2513) as

0dB

(1o-7

in/s

on

2516).

For

Hand-

Arm

measurements

to

ISO/DP

5349

(Draft

1982-02-17)

a

20dB

Charge

Attenuator

WB 0726

(for

2513)

and

a

12dB

Charge

Atten-

uator

WB 0778

(for

2516) are available.

Alter

-

natively, a

"Hand-Arm"

Transducer

Set

Type

4392

(with

2513)

or

a

Miniature

Accelerome-

ter

Type

4375

(with

2516)

may

be

used

Overload Warning:

Display

flashes

and

level

indication

is

suppressed

until

overload

is re-

moved

OTHER CONTROLS:

Reset:

Operating

any

switch

resets

the

In-

strument.

Pushing

"Reset"

indicates

battery

condition

on

the

display

On/Off: Push

for

on,

push

for

off

AC Out:

Sub-miniature

socket

accepting

2,5

mm

jack-plug

JP 0213

or

cable

AO

0173

for

connection

of

a

recorder

or

analyzer. Full

insertion

of

plug

disables

automatic

switch-

off.

Output

impedance

100

In

series

with

33µF.

Open-circuit

voltage

1V ± 6%

corre-

sponds

to

full

scale

Indication.

Min.

load

10k0

BATTERIES:

Type: 3 x 1,5V

cells

to

IEC

specification

LR6

("Penlight"

or

"AA" size), e.g.,

alkaline

cells

QB 0013

Life: 2000

Leq

measurements

or

24

hours'

continuous

measurement

In

room

lighting.

In

bright

sunlight

continuous

measurement

life

falls

to

10

hours

Specifications 4384

Acoustic sensitivity:

Typically

10

mm/

s2

(0,001 g)

at

154

dB

SPL (2

to

100Hz)

Temperature range:

~74°C

(-101°F)

to

+

250°C

(+

482°F)

Shock: ±

200km/s

2

(±

20000g)

max.

peak

parallel

to

main

axis

Vibration limit

(within

linear

frequency

range):

60km/s

2

(6000g)

continuous

peak

stnewave

along

main

axis;

1

km/s

2

(100g)

with

magnet

UA

0642

PHYSICAL CHARACTERISTICS:

Weight: t 1g (0,4oz), excl. rn,ountlng

accessories

Height:

19,6mm

(0,81n),

ex

.cl.

mounting

and

miniature

10-32

UNF

screw-locking

coaxial

connector

PHYSICAL CHARACTERISTICS:

Weight: 350g (12,4oz) excl. 4384

Height: 187

mm

(7,4 in)

with

4384

cable

disconnected

Width: 72

mm

(2,8 in)

Depth: 22

mm

(0,9 in)

Temperature Range:

-10°

to

+ 50°C (14°

to

122°F)

Humidity: O

to

90% AH

(non-condensing)

ACCESSORIES SUPPLIED:

Piezoelectric

Accelerometer

.........

..

Type

4384

Document

Folder

......................

...

.

...

..

.

...

KE 0198

1,2m (4 ft)

TNC-to-TNC

Acceler-

ometer

Cable

................

..

...............

...

..

.

AO

0193

Adaptor,

TNC

plug

to

Accelerom-

eter

............................................

....

...........UA 0641

Mounting

Magnet

...................................UA 0642

(includes 1

Ferromagnetic

Disc

.

...

.

..

...

YO

0070

and 2 PTFE

Isolating

Discs

......

...

.......DS 0553)

2,5

mm

(0,1in)

Sub-Miniature

Jack

Plug..

....

.

...

.

..

.......

..

............................ JP 0213

3

Alkaline

Cells

..

..........

...

................

..

..... QB 0013

Measurement

Record

Pad

..

....

..

....

.......

QP

4992

ACCESSORIES AVAILABLE:

2,5

mm-Jack-to-BNC

Cable

(1,5 m)

...

............

....

........

..

.....................

AO

0173

Adaptor,

10-32

UNF

miniature

coaxial

connector

to

TNC

(for

connection

of

other

Accelerome-

ter

Cables

to

2513

or

2516)..................JP 0162

20dB

Charge

Attenuator

..................... WB 0726

12dB

Charge

Attenuator

..................... WB 0778

1

kHz

High-Pass

Filter......................... WB 0772

Mechanical

Filter

.............

..

....,.............

..

UA 0559

(Available as a

set

of

5.......

...

.

..

.........

..

UA 0553)

"Hand-Arm"

Transducer

Set...

........

Type

4392

(for

2513)

Miniature

Accelerometer

....

...

........

...

Type

4375

(for

2516)

Tripod

Bush

Adaptor

..

....

...

.....

....

.......... DB 1112

Accelerometer

Calibrator

.............

...

Type

4291

Accelerometer

Calibrator

...

.............

Type

4294

Diameter: 13,5

mm

(0,53

in)

body

and

mount-

ing-surface

Base:

Titanium,

14mm

(0,6in)

hexagon,

with

central

10-32

UNF

tapped

hole

for

mounting

ACCESSORIES SUPPLIED:

1,2m (4

ft)

Accelerometer

Cable

with

miniature

10-32

UNF

screw-

locking

coaxial

connectors

.................

AO

0038

10-32

UNF

Threaded

Steel

Stud

........YO 2960

ACCESSORIES AVAILABLE:

3m

Accelerometer

Cable

with

miniature

10-32

UNF

screw-lock-

ing

connectors

.......................................

AO

0122

Tube

of

Cyanoacrylate

Adhesive

.......as0007

AC OUT:

2.

CONTROLS

--1

va1.J

Range

Selector---+----"

'T

.....

1,.

.....

-----Function

Selector

-

=.

..

11.-

1!!1!1

":

;,.

·-

·

---Reset

(Batt.)

Display----+-------<

=-20

On/Off

ImJ

-:

-•

•-..-----'Vn/Off

:

="7

•

AC

Out

=-,}

-

f·

.•

.

......,

-2

-

..

•'

Bruel

•

Kjar

...

y.,.,_

2613

t

Tripod Mounting Bush

Ffg.

2.

1.

Controls

of

the 2513

(the

controls

of

the

2516

are

identical)

Coaxial

socket

for

connection

of

a

recorder

or

frequency analyzer.

Accepts

2,5

mm

jack-plug

JP 0213 and

jack-plug-to-BNC

cable

AO 0173. Full

insertion

of

plug

disables

automatic

switch-off.

AC

out-

put

voltage

proportional

to

instantaneous

conditioned

signal (i.e.,

ac-

celeration

or

velocity,

Hand-Arm

etc., as selected). 1 V

corresponds

to

full scale

indication.

Accuracy

(including

Accelerometer)

± 6%. Output

impedance

10 n in series

with

33 µF.

Minimum

load

impedance

10 kn.

Overload level 6,2 V

pk-pk

approx.

5

DISPLAY:

FUNCTION SELECTOR:

INPUT:

ON-OFF:

RANGE SELECTOR:

6

Thermometer-type

display

scale

composed

of

41

red light-emitt:ing

di-

odes (LEDs). The brightness is

automatically

controlled

to

compensate

for

the level

of

ambient

illumination. The measured level is

indicated

by the illumination

of

one

or

two

LEDs. When the level

to

be

indicated

is

intermediate

between those

of

two

adjacent

LEDs, they both light.

Overload is

indicated

by flashing

of

the full scale LED. In the case

of

PEAK-Leq,

two

simultaneous

indications

are given -Peak (upper in-

dication), and

current

accumulated

dose

(lower indication). The

display

flashes while the

Leq

reading is building up, and

becomes

steady at the

correct

indication

after

1 minute. The

left-hand

display

scale shows

decibels

(dB) and the right-hand scale shows engineering units. The dB

graduation

values and the

engineering-units

full-scale level are shown

in

windows

and are linked

automatically

to

the setting

of

RANGE SE-

LECTOR.

Four-position

slide-switch

for

selecting the displayed function(s).

"RMS

-Max":

Maximum

RMS level

to

have

occurred

since the

mea-

surement began.

Time-constant

1

s.

"RMS -1s":

Current

RMS level.

Time-constant

1

s.

"Peak -1s":

Current

Peak level.

Maximum

speed

of

response 6%

(0,5 dB)

per

µs. Decay

time-constant

1

s.

"Peak -Le/':

Dual-indication

setting

of

Leq

(the equivalent steady lev-

el with the same energy

content-fully

explained in

Chapter

1

).

Mea-

surement takes place

during

the

first

60

s

after

the

function

is

select-

ed.

After

60 s the measurement is

terminated

and the

two

indications

held

for

a

further

60

s.

Upper

indication

shows

maximum

Peak

to

have

occurred

since measurement started.

Lower

indication

shows

accumu-

lated

dose

during the measurement; then shows 60 s

Leq-

The

lower

indication

is removed

if

a plug is inserted

into

the AC OUT socket. The

measurement may be restarted

by

pressing RESET (BATT.).

Coaxial

socket

at the

pointed

end

of

the

instrument

for

connection

of

vibration

transducer.

Accepts

standard TNC plugs,

accelerometer

ca-

ble AO 0193 (TNC-TNC),

or

TNC

adaptor

JP 0162

for

connection

of

standard

accelerometer

cables AO 0038 (with miniature

coaxial

plugs).

Intended

for

use

with

Piezoelectric

Accelerometer

Type

4384

or

any

alternative

accelerometer.

Push-button

for

switching

the

instrument

on and off. The

display

should

operate

immediately

after

a 3 s

warm-up/reset

following

switch-

on. The

instrument

switches

off

two

minutes

after

the last reset,

except

when a plug is fully inserted

into

the AC OUT socket.

Four-position

slide-switch

for

selecting the

vibration

acceleration

or

velocity

range

of

the DISPLAY and the AC OUT socket. The full scale

level is shown in the

window

to

the

right

of

the

top

of

the DISPLAY

and is

automatically

changed when the

switch

setting

is altered. Equiv-

alent levels in

decibels

(dB) referred

to

1

µm/s

2

acceleration

or

1

nm/s

(2513)

or

10-7

in/s

(2516)

velocity

are also

automatically

shown in the

five

windows

to

the

left

of

the DISPLAY.

RESET (BATT.):

TRIPOD MOUNTING BUSH:

WEIGHTING SELECTOR:

"Acc.":

Two

acceleration

ranges,

with

full scale levels

of

1

km/s

2

(2513), 100 g (2516), in the

upper

"Acc."

position;

and 100

m/s

2 (2513),

10 g (2516), in the

lower

"Acc."

position.

"Ve/.":

Two

velocity

ranges,

with

full

scale

indications

of

100

mm/s

(2513), 10

in/s

(2516), in the

upper

"Vel."

position;

and 10

mm/s

(2513),

1

in/s

(2516), in

the

lower

"Vel."

position.

Push-button

switch

for

checking

the

battery

condition

and resetting the

instrument.

If the DISPLAY

indication

lies

within

the range

marked

"Battery"

while the

switch

is

kept

pressed, the

batteries

are

satisfac-

tory. If the

indication

is lower,

they

should be replaced (see

section

3.2). The

switch

also resets the

instrument

-i.e.,

starts

a

new

mea-

surement

in the 60 s

Leq

mode,

resets

the

Max. Peak and Max. RMS

memory,

and

restarts

the

2-minute

automatic

switch-off

timer.

Located

near the

bottom,

of

the

rear

of

the

instrument

case. The thread

is UNC 1

/4

in x 20 (standard

tripod

mounting-thread).

Three-position

switch

which

may

be altered using a

miniature

screw-

driver

such as QA 0001. The

position

of

the

white

spot

indicates

the

weighting

selected.

"H-A":

For

measurement

of

Hand-Arm

vibrations

between 8 Hz and

1 kHz. For

measurements

to

ISO/DP

5349, RANGE SELECTOR should

be

set

to

one

of

the

"Vel."

positions

(normally

the

upper

position)

when

"H-A"

is selected.

"Sev.":

For

measurement

of

Vibration

Severity, 10 Hz

to

1 kHz. For

measurements

to

ISO 2954, RANGE SELECTOR should be

set

to

one

of

the

"Vel."

positions

when

"Sev."

is selected. Can also be used

to

provide

1 kHz

low-pass

filter

with

RANGE SELECTOR in one

of

the

"Acc."

positions.

"Lin.": The

frequency

response

is flat (linear) ± 3 dB

for

the

parameter

selected

(acceleration

or

velocity)

between 10 Hz and 1OkHz. The

rate

of

signal

attenuation

at

frequencies

below

and

above

this

range

is

18

dB

per

octave

and

-18

dB

per

octave

respectively.

7

3.

OPERATION

3.1. INTRODUCTION

This

Instruction

Manual tells you all you should need

to

know

about

the

correct

opera-

tion

of

the Types 2513 arid 2516

Integrating

Vibration

Meters. However, many

other

general

aspects

of

vibration

measurement

must

be

considered

by

the 2513/6 user

if

the

measurements

obtained

are

to

be accurate, repeatable and meaningful.

Many

of

these

aspects

are

discussed

in the

accompanying

introductory

booklet

"Measuring

Vibration",

which

should be read in

conjunction

with

this

Instruction

Manual. For convenience in the

field, a

short-form

Instruction

Manual is included, and

short-form

instructions

are also

printed

on the

back

of

the 2513/6. Your B & K representative can

supply

you

with

further

advice

and

applications

literature

relating

to

your

specific

vibration-measurement

re-

quirements.

3.2. BATTERY INSTALLATION

8

The Types 2513 and 2516 are

powered

by three 1,5 V alkaline cells

of

IEC size LR6

(AA

size,

"penlight"),

B & K

order

number

QB 0013.

To

install

or

replace these,

proceed

as

follows:

1. Slide

off

the

bottom

panel (marked "BATTERY

COVER")

in the

direction

of

the

arrow

marked

"OFF".

2.

Slide

out

installed batteries,

if

any.

3.

Insert fresh

batteries

into

the

bottom

of

the instrument,

taking

care

to

get

the

polari-

ty

correct,

as

indicated

in the

diagram

on the case.

4.

Slide the

battery

cover

back

on, in the

direction

of

the

arrow

marked

"ON"

(getting

it

the

wrong

way

round can

make

it

difficult

to

remove

Fresh alkaline

batteries

will

give

approximately

2000 60 s

Leq

measurements,

24

hours'

continuous

measurement

in

room

lighting,

or

1O

hours'

continuous

measurement

in sun-

light.

To

ensure

validity

of

measurements, press

ON/OFF

to

switch

the

instrument

on

and

check

the

battery

condition

before

use by pressing RESET (BATT.). Healthy

batter-

ies are

signified

by a DISPLAY

indication

within the

"Battery"

range while the

switch

is

kept

pressed.

Dry

batteries

of

the

correct

size

may

be used in the 2513

or

2516. However, they are

not

recommended

as

their

lives are

shorter

than alkaline

batteries

and less predictable.

There

may

also be a

greater

risk

of

damage

to

the

instrument

from

exhausted

dry

batteries.

If the

instrument

is

stored

for

a long time, the

batteries

(of

whatever

type) should be

removed

to

avoid

any

risk

of

their

leaking and

damaging

the instrument.

G)

810476

Fig. 3.1.

Mounting

the 2513 in the document folder

KE

0198

3.3. MOUNTING THE 2513 AND 2516

The 2513 and 2516 have a UNC 1

/4

in x

20

threaded

socket

in the rear panel

so

that

either

Vibration

Meter

may

be mounted on a

tripod

or

secured in the

Document

Folder

KE 0198 supplied (see Fig.

3.1

). For mounting the

Vibration

Meter

on a

tripod

with

a

3/8

inch bush, an

adaptor

DB 1112 is available as an

accessory.

The plastic

container

DZ 9576

attached

to

the Folder has

two

unthreaded lugs

to

engage

with

the

socket

on

the

Vibration

Meter, enabling the latter

to

be mounted

for

use

by

either

right-handed

or

left-handed

personnel. The Folder can

accommodate

a

pad

of

A4 Machine

Vibration

Record Sheets QP 4992 (one supplied; more may be

obtained

from

B & K representa-

tives), and when shut

protects

the 2513/6 from damage. The

Accelerometer

should be

secured

by

clamping

it

magnetically

to

the metal plate in the

plastic

container

using the

Mounting

Magnet

supplied,

with

the cable

wrapped

round the

plastic

container

as shown

in Fig. 3.1. If the Folder is

to

be used by left-handed personnel, the

metal

plate should be

unfastened and

moved

to

the other end

of

the plastic

container.

Fig.

3.2

.

Removing

the 251316

from

the

Document

Folder

KE

0198

When the Folder is opened

for

measurement

or

note-taking,

the

front

cover

should be

folded

right

back

and fastened

to

the

back

cover

using the

press-studs

provided

on the

9

flap. The Folder can then be

supported

and held

with

one

hand, using

the

strap

as

shown

in Fig.

3.1

(5).

To

facilitate

removal

of

the

2513/6

from

the Folder, the

plastic

container

has a hole at each end,

enabling

the

instrument

to

be pushed

out

from

the

rear

(Fig. 3.2).

3.4. CONNECTING UP AND MOUNTING THE ACCELEROMETER

10

Fix

the

TNC-to-miniature-plug

Adaptor

UA

0641

to

the

Accelerometer

Type 4384, and

connect

the

Accelerometer

to

the

Vibration

Meter

using

the

TNC-to-TNC

cable

AO 0193

supplied

(see Fig.

2,

Chapter 1

).

For

Hand-Arm

vibration

measurements

to

ISO/DP

5349

(1982-02-17),

a Charge

Attenuator

should _be

interposed

between

the

Accelerometer

ca-

ble and the

Vibration

Meter,

or

an

alternative

Miniature

Accelerometer

should

be

used,

as

explained

in

section

3.6. If

vibration

measurements

are

to

be

taken

on

light-weight

structures,

the alternative

Accelerometer

Cable

AO 0038 should be used

connected

di-

rectly

to

the Accelerometer. If the

Vibration

Meter

is

to

be

operated

a

greater

distance

from

the

Accelerometer, Reinforced 3 m

Accelerometer

Cable

AO 0122 (available as an

accessory),

may

be used,

connected

directly

to

the

Accelerometer.

Each

of

these

alter-

native

cables, and the alternative

Miniature

Accelerometers

suggested

for

Hand-Arm

vibration

measurements, require

Adaptor

JP 0162 (available as an

accessory)

to

connect

it

to

the

Vibration

Meter. Cable in free length and sets

of

connectors

can also

be

ob-

tained.

Details are available

from

B & K

representatives

.

Note

that

although

the length

of

the

cable

used

does

not

affect

the

calibration

of

the

Vibration

Meter.

the use

of

very

long

connecting

cables can lead

to

an increase in the

noise

level,

making

measurement

of

very

low

vibration

levels

impossible.

The

Accelerometer

should

be

firmly

mounted

on the

vibrating

object,

using the

Mounting

Magnet

UA 0642 supplied (Fig.

2,

Chapter

1

),

or

one

of

the

alternative

mounting

methods

described

in

Chapter

1 and the

booklet

"Measuring

Vibration".

Firm

mounting

of

the

Accelerometer

is essential as the

method

and

quality

of

mounting

can influence the

response

to

high frequencies. The

accuracy

of

some

measuremel"!_ts

may

be

adversely

affected

if

unsuitable mounting

methods

are used.

Attention

to the

quality

of

Accelerometer

mounting

is

important

even

if

the

measurement

is

to

be

made with WEIGHTING SELECTOR

set

to

"H-A"

or

"Sev"

(which have

upper-

frequency

limits

of

1 kHz). As

explained

in the

booklet

"Measuring

Vibration",

insecure

mounting

of

the

Accelerometer

can lead

to

a

considerable

change

in

its

frequency

re-

sponse,

bringing

the mounted resonance

frequency

inside

the 10 kHz

frequency

range

of

the

Vibration

Meter.

Excitation

of

this

resonance can

cause

an

overload

indication

on

the

DISPLAY resulting from the

overload

of

the

circuit

stages

preceding the

weighting-

filters

in the

Vibration

Meter.

Mounting

the

Accelerometer

on a

Mechanical

Filter

UA

0559, available as an accessory,

provides

the

most

depen(:table

insurance

against

this

type

of

occurrence.

Note

that

the

Magnet

supplied

is

of

an

improved

design

capable

of

giving

accurate

results

over

the full frequency

range

of

the

Vibration

Meter

with

the

Type

4384

Acqeler-

ometer

supplied. However,

to

achieve

this, the

magnetic

surface

to

which

the

magnet

is

attached

must be

smooth

and should be

lightly

smeared

with

silicone

grease. The

grease

is

not

necessary

if

Hand-Arm

or

Severity

is

to

be measured.

The PTFE isolating

discs

DS

0553

(two

supplied)

enable the

Accelerometer

to

be

electri-

cally

insulated

from

the mounting surface. This is useful

to

prevent

the

formation

of

earth-loops

when the Vibration

Meter

is

connected

to

other

instruments.

The

discs

are

not

intended

for

protecting

the

instrument

or

the

user

against

hazardous

voltages

on the

vibrating

object.

When

mounting

the

Accelerometer

on a threaded stud, slacken

off

the

locking-ring

of

the TNC

connector

first

to

enable the

Accelerometer

and

Adaptor

to

be rotated

without

twisting

the cable.

3.5. TAKING A VIBRATION MEASUREMENT

The

procedure

for

taking a

vibration

measurement

with

the 2513

or

2516 is as follows:

1.

Check

the

batteries

as described in section 3.3.

2.

Connect

up

the

Accelerometer

and

mount

it on the

vibrating

object

as

described

in

section 3.4.

3.

Using a

miniature

screwdriver

such as

QA

0001, set WEIGHTING SELECTOR

to

"H-A"

for

Hand-Arm

measurements

to

ISO/DP 5349,

"Sev"

for

Vibration

Severity

measurements

to

ISO 2954,

or

"Lin"

for

wide;.band

measurements

(1

OHz

to

1OkHz), as required.

4.

Set RANGE SELECTOR

to

the

upper

"Acc."

or

"Vel."

position

as required. For

Hand-Arm

and

Vibration

Severity measurements

it

should be

set

to

the

upper

"Vel."

position. For

parameter

selection with wide-band measurements, refer to the

discus-

sion in the

booklet

"Measuring

Vibration".

5.

Set FUNCTION SELECTOR as required. Refer

to

Chapters

1 and 2

for

full

descrip-

tions

of

the

four

functions, and

to

"Measuring

Vibration"

for

a

discussion

of

the

methods

of

quantifying

vibration

level.

6.

Switch the

Vibration

Meter

on (if it is off) by pressing

ON/OFF

once, and

wait

3 s

for

it

to

warm

up/reset.

The instrument turns itself

off

automatically

two

minutes

after

the

operation

of

any

of

the controls,

to

conserve

the

batteries.

This

automatic

switch-off

may

be prevented by inserting the 2,5

mm

sub-miniature

jack-plug

JP 0213 supplied

into

the AC OUT socket.

7.

If the

displayed

indication

does

not

rise above the

lower

end

of

the scale, set

RANGE SELECTOR one position lower.

8.

If DISPLAY

overload

indications are experienced

which

cannot

satisfactorily

be

pre-

vented by changing the RANGE SELECTOR setting, the cause

may

be high frequen-

cies

overloading

the

input

circuits

of

the

Vibration

Meter. These usually result from

unsatisfactory

mounting

of

the Accelerometer (see

section

3.4).

Mount

the

Acceler-

ometer

more

securely,

or

remount

it

using a

method

known

to

give

a

better

high-

frequency response,

or

use a Mechanical Filter UA 0559 (available as an accessory).

The details

of

how

the DISPLAY indicates the

vibration

level are

explained

in

Chapter

1,

and summarized in

Chapter

2.

For

information

on

how

to

interpret

Hand-Arm

measure-

ments, see

section

3.6. When taking readings with the

right-hand

DISPLAY scale (engi-

neering _units),

check

the full scale indication shown in the

window

and,

if

necessary,

multiply

the actual

indication

by

1O

or

0,

1 as

appropriate.

When using the

left-hand

(decibel) scale,

note

that

the reference levels are 1

µm/s

2

acceleration

and (on the 2513

only) 1

nm/s

velocity. These levels enable measurements

to

be

made

directly

in

dBA

and

dBV

to

ISO

Draft

International Standard 1683.2,

"Preferred

reference

quantities

for

acoustic

levels",

1976. (Decibels are explained in the

booklet

"Measuring

Vibration".)

For measurements

to

Standards requiring reference levels

of

1O

µm/s

2 and (2513 only)

1

O

nm/s,

subtract

20 dB from the indication. The

velocity

reference

for

the dB scale on

the 2516 is 10-7

in/s.

11

When using the Peak-measuring

capability

of

the 2513/6

to

measure

shocks

and

impul-

sive

vibrations,

note that the measurement

bandwidth

can

affect

the

accuracy

of

the

measurement. The tolerances

for

this

kind

of

measurement are given

under

Specifica-

tions in

Chapter

1,

and the user is

cautioned

not

to

use the 2513/6

to

attempt

measure-

ments

for

which

more

advanced

instrumentation

is required. However, in many

applica-

tions, such as

for

example in

making

"before-and-after"

measurements

to

evaluate

shock-isolation

treatment, reduced

accuracy

is

acceptable

because the

objective

is

to

obtain

comparative

rather than

absolute

values.

To

switch

the

Vibration

Meter off, press ON/OFF once.

3.6. FURTHER CONSIDERATIONS FOR HAND-ARM MEASUREMENTS

12

Draft

International Standard

ISO/DP

5349,

"Principles

for

the measurement and evalua-

tion

of

human exposure to

vibration

transmitted

to

the

hand"

(1982-02-17)

contains

recommendations

for

vibration

exposure

limits. Each

of

these

limits

is a

function

of

vibration

frequency and duration. In the case

of

vibration

acceleration, the

limits

in-

crease in

proportion

to

frequency

over

most

of

the frequency range. When the Type

2513

or

2516 Integrating Vibration

Meter

has WEIGHTING SELECTOR set

to

"H-A"

and

RANGE SELECTOR set

to

one

of

the

"Vel."

positions, its response

with

respect

to

vibration

acceleration falls with frequency as shown in Fig. 3.3. The frequency response

is

effectively

the reciprocal

of

the

exposure

limits, and therefore these settings

permit

measurements

to

be taken whose frequency

weighting

complies

with

ISO/DP

5349.

gX

0,31------1---t-------'~--t----------j-10

~

m

~

u ~

u

~

g

C

0.

~

X

0,1

-20

~

.c

~

i

I I

<ii

Ix

0,031--------+---------+---------"ll;:--;-30

X 0,

01

-40

L1

-------1.L0-------1~0-:-0-------;-'1.

k

Frequency (Hz) 81040411

Fig. 3.3.

Hand-Arm

(H-A)

vibration

acceleration

frequency weighting,

with RANGE SELECTOR

set

to

"Ve/."

However, in

order

to

ensure

that

the displayed

amplitude

can be read in

acceleration

units

without

the need

for

a

conversion

factor,

a suitable Charge

Attenuator

should be

installed on the

Vibration

Meter

or

an

alternative

Accelerometer

of

lower

sensitivity

should be used. Use a

20

dB Charge

Attenuator

WB 0726 with the 2513, and 12 dB

WB 0778 with 2516 (both available

to

order). The Charge

Attenuator

is screwed

directly

into

the INPUT

socket

on top

of

the

Vibration

Meter, and the

Accelerometer

cable is

screwed

into the Charge Attenuator.

Instead

of

using a Charge

Attenuator

together

with the

Accelerometer

supplied, it

may

be preferred

to

use a Miniature Accelerometer Type 4374

or

4375 (available

as

accesso-

ries) connected

directly

to

the 2513

or

2516 respectively.

Either

of

these requires an

Adaptor

JP 0162 (also available

as

an accessory)

to

connect

the integral

cable

of

the

Miniature

Accelerometer

to

the TNC

connector

on the

Vibration

Meter. Also available

for

the 2513 is the

"Hand-Arm"

Transducer Set Type 4392,

which

comprises

a Type 4374

Miniature

Accelerometer

and

two

adaptors

which

overcome

the

problem

of

the

trans-

ducer

interfering

with the

operator's

grip. The Types 4374 and 4375 are

not

Uni-Gain®,

so

a small

correction

factor

may need

to

be applied

to

the

measurements

to

compen-

sate

for

the

manufacturing

tolerance

of

the individual

Accelerometer

used. This

correc-

tion

factor

can be

determined

from the statement

of

Charge

Sensitivity

on the

calibra-

tion

chart

supplied with each Accelerometer. If the

sensitivity

of

a Type 4374 used with

Type 2513 is

greater

than

O,

1 pC

per

m/s

2 (1,0

pC/g),

the

vibration

level measured

should be

reduced

proportionately,

and vice versa. Similarly,

if

the

sensitivity

of

a Type

4375 used

with

Type 2516 is

greater

than 0,25 pC

per

m/s

2 (2,5

pC/g),

the

vibration

level

measured should be

reduced

proportionately, and

vice

versa. The nominal

sensitivity

of

the

latter

Accelerometer

is 0,3

pC

per

m/s

2•

Although the

Vibration

Meter

must be set to

"Vel."

for

Hand-Arm

measurements,

it

is an

easy

matter

to

interpret

the measurements in

vibration

acceleration

terms

as required

by

ISO/DP

5349, especially if the dB scale is used. So long as the

appropriate

Charge

Attenuator

or

alternative Miniature Accelerometer is used, a reading on the 2513

or

2516

can be interpreted as

vibration

acceleration dB re 1

µm/s

2 (10-7 g) as in

ISO/DP

5349,

or

as

vibration

velocity

dB re 1O

nm/s

on the 2513, 4 x 10-7

in/s

on the 2516.

To

convert

a

Hand-Arm

reading in dB on either instrument

to

an

acceleration

value in engineering

units, use the conversion scale in Fig. 3.4. Alternatively,

to

use the

instrument

itself

as a

conversion

scale,

proceed

as follows:

1.

Note the dB reading.

2.

Switch RANGE SELECTOR

to

one

of

the

"Acc."

positions.

3.

Locate

on the dB scale the previously-noted dB reading.

4.

Read

off

the

corresponding

value in

m/s

2

or

g's

on the

engineering-units

scale.

The

conversion

identity

for

acceleration units is 1 g = 9,8

m/s

2•

For

most

practical

purposes

1 g = 1O

m/s

2

may

be used.

ISO/DP

5349 includes proposals

for

analyzing

Hand-Arm

vibrations

in

octaves

and

third-octaves.

The 2513/6 may be combined with

other

B & K

instruments

to

perform

analysis, as discussed in sections 4.2 and 4.3

of

this

Instruction

Manual.

~dB

.

100dB

.

110dB

s

120dB

. .

130d8

.

140(dBte

.

10

-

6tns

:2HfiO~B . 16Qid~ . / 170

"

L,

l I 'I III ' l

,,

I·t

I'

I l I I I I II I I

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' I I1'

,,

I

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I'I

'i'

I /I I I II ',I I I

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0,0316

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3 4

5m$

- 2 10 15 2ft ·

30

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40

50tnr

2 100

:.

150

200250316

791071

Fig. 3.4. Scale

for

conversion

of

acceleration

level (dB re 1

µmls

2) to

absolute

acceleration

units

mls

2.

Note: 1g = 9,8

mls

2

13

3.7. DETERMINATION OF CREST

FACTOR

14

-=-so

R-1

i

-

=-20

On

/Off

--

-

-=

-10

•

-

-:1

-

-::., }

Crest

factor

3,

75------

am

-.-.•.

~

~>

. 8

....,

0,

-2

0.

CD

__

_

..;

y1

B

nl

el &

Kj•

r + Type

25

13

Fig. 3.5.

Example

of

crest-factor

determination

.

Crest

factor

= (133 -121,5)

dB

= 11,5

dB

3,75:1

The

crest

factor

of

a steady

vibration

is

defined

as the

ratio

of

the

peak

level

to

the

RMS level. The Type 2513/6 RMS

indication

can

tolerate

exceptionally

high

crest

factors

without

reduction in accuracy.

Vibrations

with high

crest

factors

are rich in

harmonics

and have relatively

low

duty

cycles. The crest

factor

can

therefore

be used as a

guide

to

the

nature

of

the

vibration

source.

To

measure the crest

factor,

proceed

as follows:

1.

Measure

the

vibration

level

for

one

minute

(i.e., until the DISPLAY

stops

flashing)

with

the FUNCTION SELECTOR set

to

"Peak

-Leq".

2.

Using the dB scale,

subtract

the

lower

indication

from

the upper. The result is the

crest

factor,

in dB.

3.

To

convert

this value to a

numerical

ratio,

count

the

same

number

of

dB

up

from

the

bottom

end

of

the dB scale. The

corresponding

point

on the

engineering

units

scale

is the required

ratio

(see

example

in Fig. 3.5).

BRUEL & KJAER 2513 User manual

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