AbstractIn this work we share our experience in the deployment of a Wireless Gas Sensor Network (WGSN) in an operational boiler facility. Our setup is based on a state-of-the-art WGSN platform which ensures reliable gas detection and long–term operation of the network. We first describe the deployment of the network and then evaluate its wireless links using Received Signal Strenght Indicator (RSSI) and Link Quality Indicator (LQI) metrics

Baranov, Alexander

Passerone, Roberto

Sleptsov, Vladimir

Somov, Andrey

Spirjakin, Andrey

Spirjakin, Denis

In this work we share our experience in the deployment of a Wireless Gas Sensor Network (WGSN) in an operational boiler facility. Our setup is based on a state-of-the-art WGSN platform which ensures reliable gas detection and long-term operation of the network. We first describe the deployment of the network and then evaluate its wireless links using Received Signal Strenght Indicator (RSSI) and Link Quality Indicator (LQI) metrics

Andrey Somova

Denis Spirjakinb

Andrey Spirjakinb

Er Baranovb

Vladimir Sleptsovb

Roberto Passeronec A

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Safe delivery of sensed data in wireless sensor networks for gas leak detection: a boiler facility scenario

Andrey Somov

Denis Spirjakin

Andrey Spirjakin

Alexander Baranov

Vladimir Sleptsov

Roberto Passerone

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Procedia Engineering

Safe Delivery of Sensed Data in Wireless Sensor Networks for Gas Leak Detection: a Boiler Facility Scenario

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Safe Delivery of Sensed Data in Wireless Sensor Networks for Gas Leak Detection: a Boiler Facility Scenario 

 Procedia Engineering  47 ( 2012 )  873 – 876 
1877-7058 © 2012 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Symposium Cracoviense 
Sp. z.o.o.
doi: 10.1016/j.proeng.2012.09.286 
Proc. Eurosensors XXVI, September 9-12, 2012, Kraków, Poland 
Safe delivery of sensed data in wireless sensor networks for 
gas leak detection: a boiler facility scenario 
Andrey Somova,*, Denis Spirjakinb, Andrey Spirjakinb, Alexander Baranovb, 
Vladimir Sleptsovb, Roberto Passeronec a 
aCREATE-NET, Via alla Cascata 56/D, 38123 Trento, Italy  
bMoscow State Aviation Technological University, Orshanskay 3, 121552 Moscow, Russia 
cUniversity of Trento, Via Sommarive 5, 38123 Trento, Italy 
 
Abstract 
In this work we share our experience in the deployment of a Wireless Gas Sensor Network (WGSN) in an operational 
boiler facility. Our setup is based on a state-of-the-art WGSN platform which ensures reliable gas detection and long-
term operation of the network. We first describe the deployment of the network and then evaluate its wireless links 
using Received Signal Strenght Indicator (RSSI) and Link Quality Indicator (LQI) metrics.  
 
© 2012 Published by Elsevier Ltd. 
 
Keywords: wireless sensor network; communication; catalytic gas sensor; gas leak; WSN deployment; WSN performance. 
1. Introduction 
Nowadays, methane monitoring in boiler facilities is performed by wired systems [1]. The major 
drawbacks of wired monitoring systems are their maintenance cost and their large demand in terms of use 
of cables which constrain the way the system can be deployed. Recently, the trend has been to shift 
towards the application of the Wireless Sensor Network (WSN) paradigm for gas monitoring, which can 
easily be deployed anywhere it is required and provides high flexibility and ease of maintenance. The use 
of this technology is today possible thanks to semiconductor and catalytic sensors with low power 
consumption on board of a WSN node that are able to meet the standard [2] of gas monitoring and energy-
aware sensing [3] requirements. 
 
* Corresponding author. Tel.: +39-0461-408 ext. 406; fax: +39-0461-421-157. 
E-mail address: asomov@create-net.org. 
Available online at www.sciencedirect.com
© 2012 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Symposium Cracoviense 
Sp. z.o.o. Open access under CC BY-NC-ND license.
Open access under CC BY-NC-ND license.
874   Andrey Somov et al. /  Procedia Engineering  47 ( 2012 )  873 – 876 
In this paper we present a novel application where a WSN is used to monitor methane levels in an 
operational boiler facility in Moscow. Since the sensing capabilities have been evaluated in our recent 
work [3][4] this contribution focuses on the evaluation of wireless communication between the network 
coordinator and the sensor nodes. In such a safety-critical application, the measured data must arrive in 
time as well as the quality of control strongly depends on the quality of wireless communication.  
2. Hardware and Network Operation 
The WGSN consists of 9 sensor nodes (Figure 1a) and 1 network coordinator (Figure 1b). The network 
coordinator is based on a STM32F102C6 microcontroller, uses a ETRX3 communication module 
(IEEE802.15.4, ZigBee, 2.4 GHz), and is plugged into the main power supply (220 V). The wireless 
sensor nodes are based on a AtXmega32A4 microcontroller and have the same communication part. The 
nodes are supplied by two 2D-batteries, wired in series. The sensor nodes can operate autonomously more 
than 1 year [3]. To support the stable communication between the nodes and coordinator, all wireless 
devices in the network have an external antenna. 
 
  
(a) (b) 
Fig. 1. (a) Wireless gas sensor node in the casing. Visible parts: antenna, power supply (2 x D-batteries, 1.5 V), and catalytic sensor 
(on the right side of packaging); (b) Network coordinator. LCD display shows the status of the sensor nodes in the network. 
 
Figure 2a shows the current flowing through the sensor and the sensor temperature during its heating 
till 450 °C which is the normal operation temperature for the sensor. The time necessary to heat the sensor 
to enable its operation is approximately 1 s. Figure 2b shows the sensor response at different 
environmental conditions. 2% CH4 can be detected in approximately 0.35 s. 
 
(a) (b) 
Fig. 2. (a) Heating temperature ‘2’ and heating current ‘1’ of the sensor w.r.t. heating time; (b) Sensor’s respons in volts (heating 
pulses are 2.8 V) w.r.t. environmental conditions: ‘1’ - air, ‘2’ – 0.25% CH4 in the atmosphere, ‘3’ – 2% CH4 in the atmosphere. 
t, s t, s 
T,
 °C
 
I, m
A
 U
, V
 
875 Andrey Somov et al. /  Procedia Engineering  47 ( 2012 )  873 – 876 
Apart from the methane measurement, the wireless sensor nodes perform self diagnostics which 
includes the monitoring of voltage level of the batteries and the sensor heater status. 
The network coordinator shows the status of four sensor nodes at a time on a TFT display. The status 
includes: 
• Sensor node ID and its availability in the network. To support this option, every 30 minutes the nodes 
send an acknowledgement to the network coordinator which updates their statuses: green window 
means the sensor node is in the network, grey window means it is out of network (see Figure 1b);  
• Battery charge status can take the values: ‘charged’, ‘voltage below 2.2 V’, ‘discharged’. 
• Current methane concentration. The WGSN operates according to two hresholds (0.5% and 1%) of 
methane concentration in the environment: (i) <0.5%: nothing happens, (ii) 0.5% – 1%: alerting of the 
network coordinator, (iii) >1%: alerting of the main control system, sound alarm, and the sensor node 
status highlighte with red colour. 
For this deployment, we have upgraded and improved the WGSN research platform we introduced in 
our previous work in [2]. For example, the current commercially-oriented platform supports remote 
reprogramming (RR) of sensor nodes and employs external antennas.  
3. Deployment and Experimental Results 
The access to a real boiler facility gives us the opportunity to experimentally evaluate the features of 
this environment which were not investigated in WGSN before. The WGSN, comprising 9 sensor nodes 
and 1 network coordinator (see Figure 1), is deployed in the boiler facilities (service rooms and the main 
hall) on a territory over 2000 m2. The sensor nodes are fixed at approximately 10 m height and one is near 
the boiler B3 as shown in Figure 3. The thickness of the brick walls is approximately 50 cm.  
 
  
(a) (b) 
Fig. 3. (a) WGSN deployed in an operational boiler facility (30 x 70 m) where C is the network coordinator, 1–9 are the sensor 
nodes, B1–B3 are the boilers; (b) sensor node ʋ6 near boiler B3 
 
The first experiment (see Figure 4a) demonstrates that links with low RSSI might have high LQI and 
vice versa. For example, the location of sensor node ʋ7 ensures approximately the same RSSI value as 
for the sensor node ʋ6, but this signal has the lowest LQI and can not be demodulated.  
For the evaluation of LQI and RSSI stability during a 24-hours deployment in the boiler environment, 
we measured both metrics between sensor node ʋ3. The LQI level is sufficiently stable during the day 
time (0-250 and 850-1565 minutes). However, there might be significant LQI drops during the night 
(9pm-7am or 250-850 minutes in Figure 4b). The RSSI is less stable even during the day, but is generally 
around -80 dBm. In night hours, the RSSI may be reduced up to almost -90 dBm. This can be explained 
by the harsh environment of the boiler facility, e.g., the night temperature in the beginning of May in 
Moscow can reach 12 °C (26 °C during the day time) that also impacts the level of humidity.  
876   Andrey Somov et al. /  Procedia Engineering  47 ( 2012 )  873 – 876 
-86 -85 -84 -83 -82 -81 -80 -79 -78
20
40
60
80
100
RSSI, dBm
PD
R
,
 
%
 
 
80 100 120 140 160 180 2000
20
40
60
80
100
LQI
PD
R
,
 
%
 
 
1 2 3 4 5 6 7 8 9-100
-50
0
50
100
150
200
250
300
Sensor node
Va
lu
e
 
LQI
RSSI, dBm
0 500 1000 15000
200
400
LQ
I
 
 
-90
-80
-70
Time, minutes
RS
SI
,
 
dB
m
RSSI, dBm
LQI
 
 
 
 
 
 
 
 
 
  a)       b) 
Fig. 4. (a) Wireless link assessment between each sensor node and the network coordinator using LQI and RSSI metrics (average 
values after 100 measurements); (b) LQI and RSSI evaluation during 1565 minutes (approximately 26 hours). 
 
Figures 5a and 5b plot the Packet Delivery Rate (PDR) values w.r.t. RSSI and LQI. A good link 
(PDR>80%) can be achieved when the RSSI is higher than -79.3 dBm and the LQI is over 200.4. 
 
 
 
 
 
 
  a)       b) 
Fig. 5. Relation between (a) RSSI and average PDR; (b) LQI and average PDR 
 
The experimental results show that both the RSSI and LQI metrics should be carefully analyzed before 
the WSN deployment in a safety-critical environment: the dangerous gas can be detected within 1 s, but 
the data delivery may fail due to low LQI at high RSSI. 
Acknowledgements 
We acknowledge the NATO Collaborative Linkage Grants CBP.CLG.984158 and Russian Federal 
Program “Development of Electronic Components and Radio Electronics” Grant No. 01.426.11.0050. 
References 
[1]  PlottnerM, Berger O, Stab H, Fischer WJ, Konig P, Schwartz A. Miniaturized gas monitoring system employing several 
SAW sensors. In: Proceedings of the International Frequency Control Symposium and PDA Exhibition, Seattle, WA, USA, 
2001, p. 520-527. 
[2]  Standard EN 50194:2000: Electrical Apparatus for the Detection of Combustible Gases in Domestic Premises. Test 
methods and performance requirements (2000). 
[3]  Somov A, Baranov A, Savkin A, Ivanov M, Calliari L, Passerone R, Karpov E, Suchkov A. Energy-aware gas sensing 
using wireless sensor networks. In: Proceedings of the 9th European Conference on Wireless Sensor Networks, Trento, 
Italy, 2012, p.245-260. 
[4]  Somov A, Baranov A, Savkin A, Spirjakin D, Spirjakin A, Passerone R. Development of wireless sensor network for 
combustible gas monitoring. J Sensors and Actuators, A: Physical 2011; 171:398-405. 


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