1. New Cosmos Electric, Co., Ltd.,
October, 2015 ICHS, Yokohama
Performance evaluation of the miniaturized
catalytic combustion type hydrogen sensor
Hiroshi Miyazaki, Hiromasa Tanjyoh, Kengo Suzuki, Tomoaki Iwami
New Cosmos Electric, Co., Ltd.,
Osaka, Japan

2. Outline 1. Background 2. Structure and characteristic of
the miniaturized hydrogen sensor
3. Evaluation of response property
by the hydrogen diffusion experiment
4. Summary

3. Backgrounds Key point of hydrogen alarm systems
New Cosmos electric develops, manufactures, and provides of hydrogen safety-related products and maintenance
Key point of hydrogen alarm systems
Early detection of the hydrogen leak accident emergency 　 　　　　
Higher performance hydrogen sensor is required
detection range
response time
Accuracy
Long life
High durability 　　　　
Hydrogen alarm systems
Our gas alarm system has been adopted in
22 hydrogen stations in Japan

4. Purpose of this study Early detection of the trouble
Compressor unit on the hydrogen station
= container with forced ventilation
Hydrogen leaks out
⇒ hydrogen concentration keep low
⇒ Trouble detection is late
Early detection of the trouble
= even such a condition must detect hydrogen
Confirmed the influence that a leak point and the ventilation rate gave in the hydrogen sensor output by a hydrogen diffusion experiment

5. Structure of the m-CS sensor
The Fast-Response Hydrogen Sensor “μ-CS Sensor” 　　　　　　　　　　　　　　　
miniaturized
Φ 0.2mm
Φ 0.7mm
Conventional Detector Element
m-CS Detector Element
Micro-fabrication technology
Catalytic technology
Φ 10mm Pt wire 　　　　
Pd – Pt
Catalyst 　　　　
Alumina 　　　　　
Micro Heater Coil
Catalyst material

6. Characteristic of the m-CS sensor
1. Fast response : 90％ Response time < 1 sec.　　　　　　
2. Fast stand-up : Warm-up time < 1 sec.　　　　
3. Very low power consumption : < 65mW　　　　　　
4. Resistance to silicone compound : Deterioration rate ≦10％ 　　　　　
5. Wide temperature / humidity range : -35 to 100℃ / 0 to 100%RH 　　　
6. Long life : Sensitivity decrease rate less than 10% / 15years　　
7. High durability : High tolerance to vibration and impact strength. 　　　　
m-CS sensor　　　　　　
Φ 0.2mm　　　　

7. Evaluation result of the silicone poisoning and the life time
Silicone poisoning test
Life time test 90 10 20 30 40 50 60
Sensor output / mV 2 4 6 8 12
Time / year 14 70 80
-10
Air
H2 4000ppm
H ppm
H ppm
H ppm
H ppm
+10%
-10%
Evaluation result of silicone poisoning
Evaluation result of long-term stability
Test result of resistance to Silicone Poisoning at 1% HMDSO*1 for 20h exposure.
The μ-CS sensor life span can be expected for 15 years
The μ-CS sensor have durability to even high-concentration silicone vapor.
*1HMDSO = Hexamethyldisiloxane

8. Evaluation of the response properties
T90 response time
(= 90% arrival time to saturated output)
μ-CS sensor = 0.7 sec.
Conventional sensor = 3.5 sec.
Figure. Constitution outline of the
response evaluation setup
1000
2000
3000
4000
5000
6000 20 40 60 80
100
Time / sec.
Sensor output
(H2 concentration conversion) / ppm
m-CS sensor
Conventional sensor
10sec.
10sec. cycle
1000
2000
3000
4000
5000
6000
Sensor output
(H2 concentration conversion) / ppm 1 2 3 4 5 6 7 8 9 10 11 12
Time / sec.
m-CS sensor
Conventional sensor
1sec.
1sec. cycle
The response properties to 5000ppm hydrogen comparison between the μ-CS sensor and the conventional sensor.

9. The hydrogen diffusion experiment
Experiment method
Figure. The setup simulating unit
The ventilation rate on this condition is about 1.1times/min, in other words, an air in the container is substituted at the rate of 1.1 times for 1min.

10. The hydrogen diffusion experiment Result 1-1
TEST-1 H2 Leakage:2L/min
-2000
2000
4000
6000
8000
10000
12000 5 10 15 20 25 30 35 40 45 50
Time / sec.
Sensor output
(H2 concentration conversion) / ppm
Alarm level
m-CS sensor
Start
3.8s
30s
Conventional
sensor
μ-CS sensor output sharply fluctuate.
The fluctuation of the conventional sensor output was smaller than μ-CS sensor.
Warning time of μ-CS sensor is 3.8sec. and the conventional sensor is 30sec..
The fast response sensor is useful for the early detection of the hydrogen leak.

11. The hydrogen diffusion experiment Result 1-2
TEST-1 H2 Leakage:1L/min
-1000
1000
2000
3000
4000
5000 10 20 30 40 50 60 70
Time / sec.
Sensor output
(H2 concentration conversion) / ppm
m-CS sensor
Conventional sensor
Start
TEST-1 H2 Leakage:0.1L/min
Time / sec.
-100
100
200
300
400
500 10 20 30 40 50 60 70
Sensor output
(H2 concentration conversion) / ppm
m-CS sensor
Conventional sensor
Start
The fluctuation of μ-CS sensor's output was observed even the lower H2 leakage rate.

12. The hydrogen diffusion experiment Result 2
-1000
1000
2000
3000
4000
5000
6000 5 10 15 20 25 30 35 40 45 50
Sensor output
(H2 concentration conversion) / ppm
Alarm level
m-CS sensor
Conventional sensor
Time / sec.
Start
TEST-2 H2 Leakage:2L/min
In the case of high ventilation rate
Hydrogen leaks out
⇒ Hydrogen concentration keep low
μ-CS sensor output reached the alarm level
Useful for the construction of the hydrogen alarm system

13. The hydrogen diffusion experiment Result 3
TEST-3 H2 Leakage:2L/min
-2000
2000
4000
6000
8000
10000
12000 5 10 15 20 25 30 35 40 45 50
Sensor output
(H2 concentration conversion) / ppm
Alarm
level
m-CS sensor
Conventional sensor
Time / sec.
Start
The fluctuation of the μ-CS sensor output was extreme.
The local hydrogen concentrations greatly fluctuate under the influence of the complicated air flow.
The μ-CS sensor can detect a change of local hydrogen concentration at the real time.

14. The hydrogen diffusion experiment Result 4
TEST-4 H2 Leakage:0.1L/min
-1000
1000
2000
3000
5000 10 20 30 40 50 70 80
Time / sec.
Sensor output
(H2 concentration conversion) / ppm
m-CS sensor
Conventional sensor
Start 60
4000
In the case of Fan OFF = Poor ventilation (natural ventilation)
Hydrogen concentration = proportional to quantity of leakage
The μ-CS sensor and conventional sensor can detect

15. Summary
We had been developed the miniaturized catalytic combustion type hydrogen sensor (μ-CS) .
The μ-CS sensor’s life was estimated more than 15 years. Furthermore, μ-CS sensor had the high durability to the silicone vapor mixture conditions.
We confirmed by a diffusion experiment that a fast response sensor was suitable for the hydrogen detection under the high ventilation.
The μ-CS sensor was able to detect a change of local hydrogen concentration in real time.
We conclude that the μ-CS sensor is useful for the future hydrogen safety managements.
We would apply the μ-CS sensor to a hydrogen alarm system and a hydrogen detector for the fuel cell vehicle in future.

16. Hydrogen detector for FCV
Product of m-CS sensor
Hydrogen detector for FCV
KSV-50/51
Wearable gas detector
XP-380

18. The hydrogen diffusion experiment
Compressor unit
The setup simulating unit
Compressor unit on the hydrogen station
= container with forced ventilation

19. Diffusion experiment results
Leakage = 1 L/min
Leakage = 2 L/min
Sensor output 10 20 30 40 50
Time / sec.
m-CS sensor
conventional sensor
4000
6000
8000
10000
12000
(H2 concentration conversion) / ppm
2000
Start
Sensor output 10 20 30 40 50
Time / sec.
m-CS sensor
conventional sensor
4000
6000
8000
10000
12000
(H2 concentration conversion) / ppm
2000
Start

20. Diffusion experiment results
TEST-1 and 2 H2 Leakage:2L/min 10 20 30 40 50
Time / sec.
m-CS sensor
conventional sensor
4000
6000
8000
10000
12000
Sensor output
(H2 concentration conversion) / ppm
2000
Start
Leakage = 2 L/min 10 20 30 40 50
Time / sec.
m-CS sensor
conventional sensor
4000
6000
8000
10000
12000
Sensor output
(H2 concentration conversion) / ppm
2000
Start
Leakage = 2 L/min

21. Diffusion experiment results
TEST-1 and 4 H2 Leakage:0.1L/min (the slow leak mode)
-1000
1000
2000
3000
4000
5000 10 20 30 40 50 60 70
Time / sec.
Sensor output
(H2 concentration conversion) / ppm
Forced ventilation
m-CS sensor
Conventional sensor
Start
Natural ventilation

22. The hydrogen diffusion experiment
Experiment method
Hydrogen concentration simulation result based on the uniform diffusion model.
In this condition, H2 concentration is in 300ppm equilibrium at H2 leak rate 2L/min..