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

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

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

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 http://www.iwatani.co.jp/jpn/newsrelease/detail.php?idx=1178 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

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

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　　　　

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 H2 10000ppm H2 20000ppm H2 30000ppm H2 40000ppm +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

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.

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.

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.

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.

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

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.

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

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.

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

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

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

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

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

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..