Transcript Protection at the workplace

Integration of a gas sensor in protective clothing
February 2014
Protection at the workplace
Integration of a gas sensor in protective clothing
Auteurs:
Marijke Timmermans
Jennifer Hesse
Saxion Kenniscentrum Design en Technologie
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Veiligheid op de werkvloer is een initiatief van het kenniscentrum Design en Technologie van
Saxion. Het project richt zich op de vraag hoe de veiligheid op de werkvloer te bevorderen met
behulp van ambient technologie. Het gaat daarbij om persoonlijke veiligheid, een veilige
omgeving en veilig gedrag. Het project is gestart op 1 januari 2011 en heeft een looptijd van
vier jaar. De consortiumleden zijn Saxion, Universiteit Twente, Novay, Thales Nederland, Norma
MPM, PANalytical, TenCate Protective Fabrics, Alten PTS en Noldus Information Technology.
Daarnaast is er een wisselende groep van deelnemende bedrijven die bij gelegenheid deelneemt
in het programmateam. Het project ontvangt subsidie van de Stichting Kennis Ontwikkeling HBO
onder registratienummer RAAK PRO-2-013.
Protection at the workplace
Integration of a gas sensor in protective clothing
ISBN/EAN: Titel: Risicoanalyse en pakket van eisen
Subtitel: Auteurs:
Projectreferentie:
Uitgever: Saxion Kenniscentrum Design en Technologie
Verschijningsplaats: Enschede
Verschijningsdatum: 21 februari 2014
Status document:
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Table of contents
INTRODUCTION ........................................................................................................ 4
ELECTRONICS ........................................................................................................... 5
HOUSING .................................................................................................................. 5
THE POCKET ............................................................................................................. 6
CONCLUSIONS AND DICUSSION ................................................................................. 7
REFERENCES ............................................................................................................. 8
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Introduction
As part of the RAAK project “Protection at the workplace” Saxion was requested to deliver a
quick prototype of the integration of a gas sensor in an Enexis overall.
Electronics and battery were given as shown in picture 1 and 2.
Figure 1: Electronics gas sensor;
Figure 2: Given battery, 3 x AAA
1 = natural gas sensor
2 = buzzer
3 = 2x LED
4 = on/off switch
5 = Mini USB for charging battery
6 = step-up converter
7 = bottom housing,
* = added by Saxion
It was immediately clear that the weak part of the construction would be the connection
between battery and PCB, being subject to movement continuously. Would it be possible to use
a smaller battery, and keep battery and pcb fixed and together in one small housing? The
housing can then easily be inserted in a pocket in the overall.
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Electronics
Reasons for 3 x AAA:

Minimum voltage 3.8V due to gas sensor [1]

Running time with 3 x AAA = 40 hrs.
Principally unaware of the specs of the gas sensor 2 batteries had already been ordered. Finally
it was chosen to use LP-443440-1S-3 with a step-up converter added, increasing the voltage
from 3.7 to 5. [2]
A mini-USB was added for charging the battery. It is recommended to switch off the sensor
when charging the battery.
Housing
Around the electronics and battery a simple housing was built, see the pictures below. The
dimensions kept to a minimum. The rounded edges are applied to avoid sharp edges in the
textile, for durability, visual, and easy insertion reasons.
Figure 4 Exploded view gas sensor
Figure 3 :Assembled sensor housing
Figure 5: Dimensions housing
Figure 4: Exploded view gas sensor
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The pocket
A tight pocket is made around the housing. The pocket is located close to the shoulder:

Buzzer within hearing distance, also with a noisy environment

Out of the reach-area when the user uses the pockets at the chest

Sensor is out of the way when working

This area is relatively free of external influence: minimal accidental contact with other
surfaces when working, keeping the sensor safe and clean.
An alternative position is considered at the hip

Standard location to carry hardware: within reach, and not in the way

Use of double layer of textile of reflection stripes.

Accessible from the outside
Figure 6: Pocket of the sensor, close to the
shoulder
Figure 7: Alternative pocket, using the
reflection stripes
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Conclusions and dicussion
A quick prototype has successfully been realized for insertion of the gas sensor in the overall.
The hardware seemed larger than necessary, making the entire unit larger and heavier than
necessary. If the electronics is smaller, a smaller battery is also recommended. The smaller the
more integrated and less obtrusive.
Also other, more accessible ways to switch the sensor
on/off are worth considering.
The housing is now top and bottom glued together. A click was integrated assuming smaller
tolerances. Assembly top and bottom should be reconsidered and tested with more accurate
manufacturing/prototyping methods.
From the two pockets tested the pocket at the shoulder is recommended, it facilitates more
freedom for optimal design and sizing of the pocket. For future development it is recommended
to think about the insertion/attachment of the sensor in more detail to create a minimal
tolerances in positioning of the housing, resulting in 100% alignment of the sensors and holes
for contact between sensors and external world. Also the location of the housing should be
tested and discussed with the final users.
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References
[1]
Applied Sensors. Natural Gas Sensor. CCF02072014_0000.pdf
[2]
Dubilier. Specification of Li-polymer Rechargeable Battery.
BAK - LP-443440-IS-3 - BATTERY, LITHIUM POL, 3.7V, 0.6AH.pdf
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