ICS 17.160  
 
Reference number  
DRS 237: 2020  
© RSB 2020  
  
 RWANDA 
STANDARD  DRS 
237 
 
Second edition  
2020-mm-dd 
 
Vibration  — Tolerance limits  
 
   
DRS 237: 2020  
©RSB 2020 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB2020  
All rights reserved. Unless  otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce thi s document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 237: 2020  
iii                ©RSB2020 - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ ......................  6 
2 Normative references  ................................ ................................ ................................ ............................  6 
3 Terms and definitions  ................................ ................................ ................................ ...........................  6 
4 Requirem ents ................................ ................................ ................................ ................................ ....... 10 
Annex  A (Informative)  General information on vibration and air overpressure and Blasting 
practice  ................................ ................................ ................................ ................................ .................  11 
A.1 Introduction  ................................ ................................ ................................ ................................ ..........  11 
Annex  B (informative)  General guidelines for ground vibration and air overpressure monitoring  ....... 13 
B.1 Part 1— Ground Vibration monitoring  ................................ ................................ ..............................  13 
B.1.1  General  ................................ ................................ ................................ ................................ .................  13 
B.2.1  General  ................................ ................................ ................................ ................................ .................  15 
B.2.3  Sensor coupling  ................................ ................................ ................................ ................................ ..... 1 
B.2.4  Burial or attachment methods  ................................ ................................ ................................ .............  2 
B.3 Part 3— Air overpressure monitoring  ................................ ................................ ................................ . 3 
B.3.3.1  Programming considerations  ................................ ................................ ................................ ..............  3 
 DRS 237: 2020  
©RSB 2020 - All rights reserved                  iv 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards. Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 237 was prepared by Technical Committee RSB/TC41, Environment protection . 
In the preparation of this standard, reference was made to the following standard (s): 
TZS 1471, Tolerance  limits for environmental vibration  
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second edition cancels and replaces the first (RS  237:2014) been technically revised.  
Committee membership  
The foll owing organizations were represented on the Technical Committee on Environment 
Protecti on(RSB/TC 41) in the preparation of this standard.  
Appropriate Community Sanitati on & Energy Service international (ACSE -1) 
Biofuel Rwanda  
Cimenterie du Rwanda  (CIMERWA)  
Compagnie pour l’environement et le Developement ( COPED)  
Energy water  and Sanitation Authority (  EWASA)  
Kanombe Military Hospital.  
Kinazi cassava plant  
King Faisal Hospital  
Pear Energy Co mpany  
Resources efficient  and cleaner Production Center ( RECP)  DRS 237: 2020  
v                ©RSB2020 - All rights reserved  
 Rwanda Environnent Management Company  (RWEMACO)  
Rwanda En vironnent Mangement Authority ( REMA)  
Rwanda Utility Regulatory Authority  
Sulfo Industries  
UMUTARA Polytechnic  
University of Rwanda - College of Arts and Social Sciences (UR -CASS)  
University of Rwanda - College of Science and Technology ( UR-CST)  
Rwanda Transport and Development Agency (RTDA) - co-secretariat  
Rwanda  Standards Board  (RSB) – Secretariat  
 
 DRS 237: 2020  
©RSB 2020 - All rights reserved                  6 
 Vibration —Tolerance limits  
1 Scope  
This Draft Rwanda standard specifies limits for general vibration including occupational environmental and air 
overpressure. Tolerance limits in this standard are given with a view to protect people against risk to their health 
and safety, and to minimize annoyance to people in residential premises and other sensitive sites exposed to 
vibration  
2 Normative references  
The following documents are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the edition  cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
RS ISO 45001: 2018 Occupa tional health and safety  management systems — Requirements with guidance for 
use 
3 Terms and definitions  
For the purposes of this standard , the follow ing terms and definitions apply/  
3.1 
Air overpressure  
Airborne pressure waves generated by blasting produced over a range of frequencies including those are audible 
and those, which  are below the lower end of the audible spectrum . 
3.2 
Daily exposure limit period  
Duration that is used as reference in defining daily exposure values  
3.3 
Exposure action value  DRS 237: 2020  
7                ©RSB2020 - All rights reserved  
 Exposure Action Value (EAV) is the daily amount of vibration exposure value above which action must be taken 
to control exposure  
3.4 
Exposure Limit Value ( ELV)  
maximum  permissible amount of vibration exposure value  
3.5 
Exposure value a (8)  
is the vibration magnitude that a person is exposed to in a day normalized to a period of 8 hours using the 
following formula:  
𝒂(𝟖)=𝒂√𝑻
𝟖 
where  
a vibration magnitude and ;  
T exposure period in hours.  
3.6 
Ground vibration  
Level of vibration (peak particle velocity) measured in mm/s in the ground anywhere on the sensitive site. The  
measurement point should be at least the longest dimension of foundations of building or structur e away from the 
building or structure if possible.  
3.7 
Hand -arm vibration  
Vibration which is transmitted into the hands and arms during a work activity.  DRS 237: 2020  
©RSB 2020 - All rights reserved                  8 
 3.8 
occupational environment  
Physical surrounding and social environment at workplace  
3.9  
Peak Particle Velocity  
The maximum instantaneous sum of the velocity vectors of the ground movement measured in three orthogonal 
directions (expressed in millimetres per second ). 
The resultant PPV is calculated by producing a vector sum of the three (3) separat e directional recordings:  
𝑽=√𝒗𝒗  𝟐+𝒗𝒍 𝟐+𝒗𝒕𝟐 
where  
v vertical ;  
l longitude;  and 
t transverse for every point of the recording  
3.10  
Sensitive site  
Any land within 10 m of residence, hospitals, schools, or other premises in which people could reasonably expect 
to be free from undue annoyance and nuisance caused by vibration. The 10 m will be measured from the 
boundaries of the property  
3.11  
Subsonic vibration  DRS 237: 2020  
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 Repetitive motion of an object with frequency lower than 20Hz it cannot be perceived by human ear but it can be 
felt 
3.12  
Vibration  
Mechanical oscillations or the repetitive motion of an object about an equilibrium point  
3.13  
Vibration magnitude, a  for hand -arm vibration  
Vibration magnitude , a, for hand -arm vibration is the root -mean -square acceleration  magnitude in m/s2    evaluated 
from the measurement in three orthogonal directions at the vibrating surface in contact with the hand using the 
following formula : 
 
𝒂=√𝒂𝒙𝟐+𝒂𝒚𝟐 +𝒂𝒛𝟐 
where  
 𝑎𝑥, 𝑎𝑦, 𝑎𝑧 are the root -mean -square acceleration magnitude in three orthogonal directions  
3.14  
Vibration magnitude, A for Whole Body vibration  
Vibration magnitude, A for whole body vibration is the root -mean -square acceleration magnitude  in m/s2 measured 
in one of the largest vibration of the three orthogonal directions at the supporting surface  
3.15 
Whole body vibration  
Vibration, which  is transmitted into the body, when seated or standing, through the supporting surface.  DRS 237: 2020  
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 4 Requirements  
4.1 Tolerance limits to protect people against risk to their health and safety are given in Table 1 and Table 2; 
these limits do apply mostly to occupational environment. Table 3 and Table 4 gives tolerance limits to minimize 
annoyance to people from environmental vibra tion, the limits shall be applicable to residential premises and other 
sensitive sites.  
Table 1 — Tolerance limits for whole body vibration  
Daily exposure 
limit period  Daily exposure 
limit value  Daily exposure 
action value  
8 h 1.15 m/s2 0.5 m/s2 
 
Table  2 — Tolerance for limits for hand arm vibration  
Daily exposure 
limit period  Daily exposure  
limit value  Daily exposure 
action value  
8 h  5 m/s2  2..5 m/s2  
Table  3 — Tolerance for limits for ground vibration at sensitive sites  
Limit on ground vibration   Test method  
5 mm/s PPV at all times   Seismograph (See Annex B)  
Table  4 — Tolerance for limits for subsonic vibration/air over pressure  
Limit on sensitive sites   Test method  
120 dBL at all times   S Seismograph (See Annex B)  DRS 237: 2020  
11                ©RSB2020 - All rights reserved  
 Annex  A 
(Informative)  
 
General information on vibration and air overpressure and 
Blasting practice  
A.1 Introduction  
This document is intended to provide  information to members of the public living close to blasting operations 
regarding the environmental impact of blast -induced ground vibrat ion and air overpressure  
A.2 Basics on blasting  
Each country has its own set of rules and regulation regarding the use of explosives. In each country,  blasting 
operations can only be undertaken by highly qualified personnel working under strict rules and guidelines . 
A.2.1  Environmental Impact of Blasting  
When explosives are detonated in a blast hole much of the energy is used to break up and move the ro ck or 
concrete. However, there is always some energy left over and this is converted into to vibration that travels away 
from the blast area through both the ground and air. The vibration through the air is generally known as air 
overpressure. In the case of demolition vibration can be generated by the impact of the structure on the ground 
surface.  
A.2.2.  Information on Ground Vibration  
A.2.2.1  As the ground vibration travels away from the blast area the level rapidly reduces. The level of vibration 
felt at  any location is controlled by the design of the blast, the distance to the blast and the intervening geology. 
As the vibration travels through the ground it may arrive at a building and this structure will then also vibrate. If 
people are inside the build ing then they may feel that the structure has responded in such a fashion that damage 
must have occurred.  
A.2.2.2 The level of blast vibration that causes damage to structures has been extensively investigated over 
many years by researchers worldwide. All of this research has shown that very high levels of vibration are 
required before damage is likely to occur.  
A.2.3. Air overpressure  DRS 237: 2020  
©RSB 2020 - All rights reserved                  12 
 A.2.3.1 . The vibration that travels away from a blast area through the air is both audible and sub audible.  
A.2.3.2 . Like g round vibration, levels of fair overpressure decay rapidly with distance from the blast area.  
A.2.3.3.  However, in this case the level depends to a great extent on the weather conditions at the time of blasting  as 
well as the blast design. Air overpressure travels through the air slower than vibration through the ground and it will 
therefore arrive at a location after the ground vibration.  This time lag can be as much as several seconds at distances 
over 1km.  
A.2.3.3 . As the air overpressure travels away from the blast area it may also interact with structures. When  such 
air overpressure waves arrive at a structure it may cause rattling of windows, doors etc. The level of air over 
pressure  likely  to break  windo ws is also very  well researched  and is incredibly  high. Such  levels  are only likely to 
be exceeded close to blasting operations employing unconfined explosive charges. Like ground vibration it is 
common for air overpressure levels to be recorded as peak levels. In this case the units will be Pascals or 
decibels . 
A.2.4. Human response  
As has already  been noted the human body is a very sensitive receptor for vibration.  This response is enhanced 
if that person is inside of a structure due to the response of the structure to both the ground vibration and air 
overpressure. It is also known that structures will also response acoustically causing even greater concern 
amongst people inside the structure.  
A.2.5. Human response  
It is good practice to measure the vib ration emissions from the blast site at the nearest residence.  
A.2.5. Environmental Monitoring  
A.2.6.1. Blasting is necessary in all aspects in the modern society . 
A.2.6.2. Blasting may cause some short -term environmental impact . 
A.2.6.3. Alternatives to blasting exist but usually cause more disturbance and inconvenience . 
  DRS 237: 2020  
13                ©RSB2020 - All rights reserved  
 Annex  B 
(informative)  
 
General guidelines for ground vibration and air overpressure  
monitoring  
B.1 Part 1— Ground Vibration monitoring  
B.1.1  General  
Blasting seismographs are deployed in the field to  record the levels of blast -induced ground vibration and air 
overpressure.Accuracyoftherecordingsisessential.Theseguidelinesdefinetheuser’sresponsibilitieswhen deploying 
blasting seismographs in the field and assume that the blasting seismographs conform t o the  ‘Performance 
Specifications for Blasting Seismographs”.  
B.1.2  Procedure  
B.1.2.1  . Read the instruction manual and be familiar with the operation of the instrument ; 
Every seismograph comes with an instruction manual. Users are responsible for reading the appropriate sections and 
understanding the proper operations of the instrument before monitoring a blast . 
B.1.2.2   Seismograph calibration  
Annual calibration of the seismograph is  recommended  
B.1.2.3 . Keep proper blasting  seismograph records;  
a user’s log should note, date, time, place and other pertinent data.  
B.1.2.4.   Document  the location of the seismograph  
This include the name of the structure and where these  is mograph  was placed  on the property  relative  to the 
structure. Any person shoul d be able to locate  and identify the exact monitoring location at a future date.  DRS 237: 2020  
©RSB 2020 - All rights reserved                  14 
 B.1.2.5  Knowandrecordthedistance to the blast  
The horizontal distance fromtheseismographtothe blast should be known to at least two significant digits. For 
example a blast within 1 000 m or feet would be measured to the nearest tens of meters or feet respectively and a blast 
within 10 000 m or feet would be measured to the nearest hundreds of feet or meters respectively. Where  elevation 
changes exceed 2.5 h: 1v,slant  distances or true distance should be used . 
B.1.2.6   Record the blast  
When seismographsaredeployed inthefield, the timespentdeployingtheunit justifiesrecordinganevent. As practical,  set 
thetriggerlevelslowenoughto record  a blast.  
B.1.2.7  Record the full time history waveform  
A paragraph summary or single peak value recording options available on many seismographs should not be used for 
monitoring blast -generated vibrations. Operating modes that report peak velocities over a specified time interval are 
not recommended when recording blast - induced vibrations . 
 
B.1.2.8  Set the sampling rate  
The seismograph should be programmed to record the entire blast event in enough detail to accurately reproduce 
the vibration trace. In general the sample rate should be at least 1000 samples per second . 
B.1.2.9  Know the data processing time of the seismograph  
Some units take up to 5 min to process and print data. If another blast occurs within this time the second blast 
may be missed . 
B.1.2.10   Know the memory or record capacity of the seismograph  
Enough  memory  must  be available to  store  the event.  The full wave  form should  be saved  for future  reference  neither 
digital  or analogy  form. 
B.1.2.11.  Know the nature of the report that is required  
For example, provide a hard copy in the field; keep digital data as a permanent record or both. If an event is to be 
printed  inthe field, a printer with paper is needed.  DRS 237: 2020  
15                ©RSB2020 - All rights reserved  
 B.1.2.12.  Allow  ample time for proper setup of the seismograph  
A para many errors occur when seismographs are hurriedly set -up. Generally, more than 15 min for set -up should 
be allowed from the time the user arrives at the monitoring location until the  blast.  
B.1.2. 13. know the temperature  
Seismographs have varying manufacturer specified operating temperatures.  
B.1.2. 14. Secure cables  
Suspended or freely moving cables from the wind or other extraneous sources can produce false triggers due to 
micro phonics . 
B.2 Part 2 - Groun d vibration monitoring  
B.2.1  General  
Placement and coupling of the vibration sensor are the two most important factors to ensure accurate ground 
vibration recordings.  
B.2.2 Sensorplacement  
B.2.2.1 The sensor should be placed  on or in the ground on the side of the structure towards the blast. A 
structure  can be a house , pipeline, telephone  pole,  etc. Measurements  on driveways,  walkways , and  slabs  are to 
be avoided where  possible.  
B.2.2 2 Location relative to the structure; Sensor placement should ensure that the data obtained 
adequately represents the ground -borne vibration levels received at the structure. The sensor should be 
placed within 3.05 m (10 feet) of the structure or less than 1 0 % of the distance from the blast, whichever is 
less. 
 
B.2.2.3  Soil density evaluation. The soil should be undisturbed or compacted fill. Loose fill material, 
unconsolidated soils, flower -bed mulch or other unusual mediums may have an adverse influence on  the 
recording  accuracy.  
B.2.2.4  The sensor must be nearly level  DRS 237: 2020  
1                ©RSB2020 - All rights reserved  
  
B.2.2.5.  The longitudinal channel should be pointing directly at the blast and the bearing should be 
recorded.  
B.2.2.6  Where access to a structure and/or property is not availa ble, the sensor should be placed closer 
to the blast in undisturbed  soil. 
 
B.2.3  Sensor coupling  
B.2.3.1  If the acceleration exceeds 1.96 m/s2 (0.2 g), decoupling of the sensor may occur. Depending on 
the anticipated acceleration levels spiking, burial, or sandbagging of the geophone to the ground may be 
appropriate.  
B.2.3.2  If the acceleration is expected  to be: 
a) less than 1.96 m/s2 (0.2 g), no burial or attachment is  necessary;  
 
b) between 1.96 m/s2 (0.2 g), and 9.81 m/s2 (1.0 g), burial or attachment is preferred. Spiking may be 
acceptable;  and 
 
c) greater than 9.81 m/s2 (1.0 g) , burial or firm attachment is  required.  
 
B.2.3.3  The following table exemplifies the particle velocities and frequencies where accelerations are 
1.96 m/s2 (0.2 g) and 9.81 m/s2 (1.0g).  
Table B.1 — Particle velocities and frequencies for accelerations  
Frequency, 
Hz 4 10 15 20 25 30 40 50 100 200 
Particle  
Velocity  
mm/s (in/s) at  
1.96 m/s2 (0.2 
g) 78.0 
(3.07)  31.2 
(1.23)  20.8 
(0.82)  15.6 
(0.61)  12.5 
(0.49)  10.4 
(0.41)  7.8 
(0.31)  6.2 
(0.25)  3.1 
(0.12)  1.6 
(0.06)  
Particle Velocity  
mm/s (in/s) at  
9.81 m/s2 (1.0  
g) 390 
(15.4)  156 
(6.14)  104 
(4.10)  78.0 
(3.07)  62.4 
(2.46)  52.0 
(2.05)  39.0 
(1.54)  31.2 
(1.23)  15.6 
(0.61)  7.8 
(0.31 ) 
 
 
  
©RSB 2020 - All rights reserved                  2 
 B.2.4  Burial or attachment methods  
 
B.2.4. 1 The preferred burial method is excavating a hole that is no less than three times the height of the 
sensor, spiking the sensor to the bottom of the hole, and firmly compacting soil around and over the sensor.  
B.2.4.2  Attachment to bedrock is achieved by bolting, clamping or adhering the sensor to the rock surfa ce 
B.2.4.3  The sensor may be attached to the foundation of the structure if it is located within ± 0.305 m (1 - foot) 
of ground level. This should only be used if  burial, spiking or sandbagging isnotpractical.  
 
B.2.5  Other sensor placementmethods  
 
B.2.5.1  Shallow burial is anything less than described inB.2.4.  
B.2.5.2  Spiking entails  removing the sod, with minimal disturbance of the soil and firmly pressing the sensor 
with the attached spike(s) into theground  
B.2.5.3  Sand bagging requires removing the sod with minimal disturbance to the soil and placing the 
sensor onthebarespotwitha sand bagover top. Sand bagsshould belargeandlooselyfilledwithabout 4.55 k (10 
pounds) of  sand. When placed over the sensor the sandbag profile should be as low and wide as possible with a 
maximum amount of firm contact with the ground.  
B.2.5.4  A combination of both spiking and sandbagging gives even greater assurance that good coupling 
isobtained.  
B.2.5.5  Programming considerations  
B.2.5.6  Site conditions dictate certain actions when programming the seismograph . 
B.2.5.6.1  Ground vibration trigger level - The trigger level should be programmed low enough to trigger the 
unit from blast vib rations and high enough to minimize the occurrence of false events. The level should be 
slightly above the expected background vibrations for the area. A good starting level is 1.3 mm/s (0.05 in/s).  
B.2.5.6.2  Dynamicrangeandresolution - If theseismographisnotequippedwith anauto-rangefunction, the user 
should estimate the expected vibration level and set the appropriate range. The resolution of the printed 
waveform should allow verification of whether or not the event was a blast . 
B.2.5.6.3  Recording duration - Set the record time for 2 sec longer than the blast duration plus 1 sec for 
each 335 m (1100 feet) from the blast . 
 DRS 237: 2020  
3                ©RSB2020 - All rights reserved  
 B.3 Part 3— Air overpressure monitoring  
B.3.1  general  
 
Placement of the microphone relative to the structure is the most important factor.  
B.3.2  Microphone placement  
 
The microphone should be placed along the side of the structure, nearest the blast:  
a) themicrophoneshouldbemountednearthegeophonewiththemanufacturer’swindscreenattached;  
 
b) the microphone may be placed at any height above the ground ; 
 
c) if practical, the microphone should not be shielded from the blast by nearby buildings, vehicles or other 
large barriers. If such shielding cannot be avoided, the horizontal distance between the microphone and 
shieldingobjectshouldbegreaterthantheheight of theshieldingobjectabove the microphone ; 
d) if placed too close to a structure, the air blast may reflect from the house surfac e and record higher 
amplitudes. Structure response noise may also be recorded. Reflection can be minimized by placing the 
microphone near a corner of the structure; and  microphone may be placed at any height above the ground;  
e) the orientation of the micr ophone is not critical for air overpressure frequencies below 1 000 Hz. should 
be mounted near the geophone with the manu facturer’s wind screen attached.  
B.3.3.1  Programming considerations  
B.3.3.1  Trigger level;  when onlyanairoverpressuremeasurementis desired , the triggerlevelshouldbe low 
enough to trigger the unit from the air overpressure and high enough to minimize the occurrence of false 
events. The levelshould beslightly above theexpectedbackgroundnoisefor  therea.Agoodstartinglevel is 20 Pa 
(0.20 mill bars or 120 dB)  
B.3.3.2  Recording duration;  when only recording air overpressure, set the recording time for at least 2 
seconds more than the blast duration. When ground vibrations and air overpressure measurements are 
desired on the same record, follow the guidelines for ground vibration programming (Part IIC). 
 
 
 DRS 237: 2020  
 
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