Solid State MOS Operating Principle

Solid State MOS (Metallic Oxide Semiconductor) sensors contain an electric conductor made up of a micro heater and a sensing element that is a proprietary mixture of metal oxides. As current travels through the element during exposure to clean air, a base resistance is established. When a gas comes into contact with the sensor element surface, a change in sensor resistance occurs.

• Alumina chips resistance change is caused by a loss or gain of surface electrons as a result of absorbed O2 reacting with the target gas
• The magnitude of resistance change is proportional to gas concentration
• Porous oxide layers are deposited or printed on a substrate
• Electrodes are located at the oxide/chip interface

Primary Applications for NE-MOS Sensors

▪ Crude Oil Tank Storage - Tank farms storing crude oil and H2S require continuous monitoring for gas leaks. In addition to the tanks, common leak sources include pipes and valves, which require sensors.

▪ Remote Oil / Gas Well Sites - Oil and gas well production sites require H2S protection in and around the site. Common monitoring locations include the well heads, flare stacks and storage tanks.

▪ Oil / Gas Drilling Sites - Leaks, such as blowouts in oil drilling applications, are subject to releasing large quantities of H2S gas into areas around the site. Typical gas monitoring locations include the driller stand, bell nipple, shale shaker, and mud tank.

Primary Performance Specifications

Full Scale Range	FM Certified Temperature Range	Relative Humidity Range	Response Time	Accuracy Linearity
0—100 ppm H2S & 0—300 ppm NH3	-40°C to +60°C (-40°F to +150°F)	0—95% RH Non Condensing	T50 < 4 sec. T90 < 13 sec. (20ppm range)	± 2ppm

Performance Certifications - Hazardous Approvals

▪ Factory Mutual (FM) Class 6310, 6320
▪ CSA 22.2 No. 152
▪ ANSI/ISA-S 92.0.01
▪ SIL2 by TÜV SÜD

▪ CSA | ATEX | INMETRO | GOST-R
    - Ex/AEx/EEx/BR-Ex/1Ex d IIB+H2
    - Class 1, Div/Zone 1, Groups BCD

▪ Temperature Rating: T5
▪ IP Rating 66/67
▪ Housing Rated NEMA Type 4x

Comparing Sensor Technologies

	Conventional Electrochemical Sensors	Traditional Metal Oxide (MOS) Sensors	NET SAFETY NE-MOS Sensors
Accuracy in High Temperatures	NO	NO	YES
Longevity in Extreme Climates	NO	NO	YES
Accuracy in Humid Air	NO	NO	YES
Accuracy in Dry Air	NO	YES	YES
Stable Calibration Over Time	YES	NO	YES
Fast Recovery From Concentrated Gas Exposure	NO	NO	YES
Sensor 'Sleep' Issues	NO	YES	NO

NE-MOS Technology Sensor Advancements

• Advanced Materials Throughout Sensor Construction
The properties of materials used are now application specific to increase overall performance

• Nano Structured Materials
Composition of materials is controlled at the nano-scale to increase density of "tubes" and to create consistent grain size which greatly improves response and stability

• Temperature Of Operation
Through the use of robust ceramic substrates, a much higher micro-heater temperature can be utilized which provides faster response, greater sensitivity, enhanced stability and prevents carbon build-up which is believed to be partly responsible for traditional MOS sensors "falling asleep".

Electron Microscopy Images (inset image above-right)
Figure 2. - shows increased density and uniformity of material "tubes" which absorb O2 and targeted gases.
Figure 2A. - shows traditional MOS material with it's abstract tube uniformity and low density.
Figure 2B. - shows traditional MOS material with carbon build-up which is theorized to inhibit gas absorption.

Net Safety NE-MOS Sensor Key Advantages

• Detects small quantities of gases (less than 20 ppm)

• Next generation - greatly enhanced stability and performance

• Fast H2S Response [T50 < 4 sec. | T90 < 13 sec. @ 20ppm range]

• Recovers quickly from high gas concentration exposures

• Ideally suited for dry/hot applications

• 2 Year sensor warranty