Which Gas Detector Do I Need? CO vs H2S vs O2 vs NH3 vs SO2 Malaysia
Which Gas Detector Do I Need? CO vs H2S vs O2 vs NH3 vs SO2 Malaysia
Which portable gas detector should you buy?
Do you need a CO detector, H2S detector, O2 detector, NH3 detector or SO2 detector?
For many customers, the difficult part is not choosing a brand.
The difficult part is identifying which gas actually needs to be monitored.
The OTYWELL G10S single gas detector series allows customers to select a detector according to the target gas and application.
MTM Precision is introducing five configurations:
G10S-CO - CO: 0-1000 ppm
G10S-H2S - H2S: 0-100 ppm
G10S-O2 - O2: 0-30% VOL
G10S-NH3 - NH3: 0-100 ppm
G10S-SO2 - SO2: 0-20 ppm
This guide explains how to identify the appropriate detector.
Start With the Application
Instead of asking:
"Which gas detector is best?"
start with:
"Where will I use the detector?"
Examples include:
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Boiler room
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Generator room
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Wastewater treatment plant
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Sewer
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Manhole
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Tank
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Vessel
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Cold storage
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Refrigeration plant
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Compressor room
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Factory
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Process plant
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Industrial maintenance
The application provides the first clue about which gases may need to be evaluated.
CO Detector - When Should You Consider It?
CO means:
Carbon Monoxide
The OTYWELL model for dedicated CO monitoring is:
G10S-CO
Range: 0-1000 ppm
Potential applications can include:
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Boiler rooms
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Generator rooms
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Combustion equipment
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Workshops
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Factories
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Engine-related environments
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Industrial maintenance
If CO is the identified target gas, the G10S-CO can be considered where its range matches the requirement.
CO Is Not CO2
This is an important distinction.
CO = Carbon Monoxide
CO2 = Carbon Dioxide
They are different gases.
A CO detector does not automatically measure CO2.
If the customer requests carbon dioxide monitoring, confirm that the selected detector contains the appropriate CO2 sensor.
H2S Detector - When Should You Consider It?
H2S means:
Hydrogen Sulphide
The OTYWELL model for dedicated H2S monitoring is:
G10S-H2S
Range: 0-100 ppm
Potential applications can include:
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Wastewater treatment
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Sewage
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Sewer maintenance
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Manholes
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Pump stations
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Sludge areas
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Industrial wastewater
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Palm oil mill wastewater
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Certain confined space applications
If H2S is the identified target gas, G10S-H2S can be considered.
Can I Use Smell to Detect H2S?
Human smell should not be used as a substitute for appropriate gas monitoring.
Where H2S has been identified as a hazard, suitable gas detection equipment should be used according to the workplace procedure.
Instrument-based monitoring is required rather than relying on human senses.
O2 Detector - When Should You Consider It?
O2 means:
Oxygen
The OTYWELL model for dedicated oxygen monitoring is:
G10S-O2
Range: 0-30% VOL
Potential applications can include:
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Tank entry
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Vessel inspection
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Manholes
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Pits
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Underground chambers
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Utility spaces
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Certain confined space applications
The G10S-O2 monitors oxygen.
It does not measure H2S, CO or LEL.
Is an O2 Detector Enough for Confined Space?
Not automatically.
If the work procedure requires only dedicated oxygen monitoring, an O2 detector may be considered.
However, if the required parameters include:
LEL + O2 + H2S + CO
then an O2-only detector does not provide the complete set of measurements.
An appropriate multi gas detector should be considered.
NH3 Detector - When Should You Consider It?
NH3 means:
Ammonia
The OTYWELL model for dedicated NH3 monitoring is:
G10S-NH3
Range: 0-100 ppm
Potential applications include refrigeration systems where ammonia is actually used, such as certain:
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Cold storage facilities
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Industrial refrigeration plants
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Compressor rooms
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Food processing plants
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Frozen food facilities
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Seafood processing facilities
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Meat processing plants
Always confirm the refrigerant first.
Not every cold room uses ammonia.
Does a Standard 4-in-1 Detector Measure NH3?
Not necessarily.
A commonly requested 4-in-1 configuration may contain:
LEL + O2 + H2S + CO
This does not automatically include NH3.
If ammonia is the target gas, specifically confirm that the selected detector has an NH3 sensor.
SO2 Detector - When Should You Consider It?
SO2 means:
Sulphur Dioxide
The OTYWELL model for dedicated SO2 monitoring is:
G10S-SO2
Range: 0-20 ppm
Potential applications can include certain:
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Factory environments
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Industrial processes
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Boiler areas
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Chemical processing applications
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Process plants
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Industrial maintenance activities
The actual requirement depends on the process and identified gas hazard.
Is G10S-SO2 a Flue Gas Analyzer?
No.
The G10S-SO2 is positioned as a portable single gas detector.
If the requirement is to measure SO2 directly inside a chimney, boiler exhaust, stack or process flue, a suitable flue gas or emission analyzer may be required.
Personal gas monitoring and stack emission measurement are different applications.
CO vs H2S
These gases are sometimes both found in industrial gas detector discussions, but they require different sensors.
G10S-CO
CO: 0-1000 ppm
G10S-H2S
H2S: 0-100 ppm
Choose according to the actual target gas.
H2S vs SO2
These names can also cause confusion.
H2S
Hydrogen Sulphide
OTYWELL:
G10S-H2S
Range:
0-100 ppm
SO2
Sulphur Dioxide
OTYWELL:
G10S-SO2
Range:
0-20 ppm
The detectors are not interchangeable.
NH3 vs H2S
Both may be associated with strong odours in certain environments, but they are different gases and require appropriate sensors.
NH3
G10S-NH3
0-100 ppm
H2S
G10S-H2S
0-100 ppm
Do not choose based on smell description alone.
Identify the actual gas.
O2 vs Toxic Gas Detector
Oxygen monitoring is different from monitoring toxic gases such as:
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CO
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H2S
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NH3
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SO2
The G10S-O2 measures oxygen concentration.
It does not replace a toxic gas detector when toxic gas monitoring is also required.
Quick Gas Detector Selection Table
| Application | Possible Target | OTYWELL G10S Model |
|---|---|---|
| Boiler Room | CO | G10S-CO |
| Generator Room | CO | G10S-CO |
| Wastewater | H2S | G10S-H2S |
| Sewer | H2S | G10S-H2S |
| Manhole | H2S and/or other parameters depending on requirement | G10S-H2S or suitable multi gas detector |
| Dedicated Oxygen Monitoring | O2 | G10S-O2 |
| Tank / Vessel | O2 and/or multiple gases depending on requirement | G10S-O2 or suitable multi gas detector |
| Ammonia Refrigeration | NH3 | G10S-NH3 |
| Compressor Room Using Ammonia | NH3 | G10S-NH3 |
| Dedicated Industrial SO2 Monitoring | SO2 | G10S-SO2 |
This table is a starting point only.
The final detector should match the actual risk assessment and work requirement.
What If I Need More Than One Gas?
This is where customers should consider moving from a single gas detector to a multi gas detector.
A commonly requested configuration is:
LEL + O2 + H2S + CO
OTYWELL G40S can be considered for customers requiring multi gas monitoring, depending on the selected sensor configuration.
Confirm the exact gases before ordering.
What If I Need Pump Sampling?
If the atmosphere must be sampled remotely, such as before entry into a tank, vessel, manhole or other space, a pump type detector may be required.
MTM Precision is introducing:
OTYWELL OT135S
Type: Pump Type Multi Gas Detector
MTM standard configuration:
EX + O2 + H2S + CO + CO2
The exact application and sampling requirement should be confirmed before selection.
G10S vs G40S vs OT135S
A simple way to understand the range is:
G10S
One target gas
Single gas monitoring.
G40S
Several target gases
Multi gas monitoring.
OT135S
Several gases + active pump sampling
Pump type multi gas monitoring.
This gives customers a logical progression based on the complexity of the job.
What If I Do Not Know Which Gas Is Present?
Do not guess.
Provide MTM Precision with information about:
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Application
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Industry
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Process
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Work location
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Equipment
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Existing detector
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Tender specification
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Safety requirement
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Gases mentioned by the consultant or customer
MTM Precision can help compare the available detector configurations against the stated requirement.
The actual hazard identification and safety procedure should still be determined by the responsible workplace personnel.
Personal Monitoring or Leak Searching?
These are also different requirements.
Personal Monitoring
The detector is carried by personnel to monitor the atmosphere around them according to the detector's operating principle.
Leak Searching
The objective is to locate the approximate source of a suspected leak.
A dedicated leak-search detector or different sampling method may be more suitable depending on the gas and application.
Tell MTM Precision which type of work you are performing.
Portable or Fixed Gas Detector?
Portable Detector
Carried by workers or used for temporary monitoring.
The OTYWELL G10S series is portable.
Fixed Detector
Installed permanently at selected locations for continuous monitoring.
A portable detector should not automatically replace a fixed gas detection system where permanent monitoring is required.
Some facilities may require both.
Bump Test and Calibration
Gas detector ownership does not end after purchase.
Users should understand:
Bump Test
Functional check of detector and alarm response.
Calibration
Checks detector response against an appropriate known reference and allows adjustment where required.
OTYWELL advises that instruments are 100% calibrated before shipment and can be supplied with calibration or test documentation.
After entering service, appropriate testing, calibration and maintenance should continue.
Sensor Life
For the OTYWELL G10S configurations being introduced by MTM Precision, typical sensor life is approximately:
2-3 years
Actual sensor life depends on sensor technology, gas exposure, environment, storage and maintenance.
The sensor should therefore be treated as a consumable part of the detector.
Five Questions Before Buying a Gas Detector
Before requesting a quotation, answer these five questions:
1. What gas do you need to detect?
CO, H2S, O2, NH3, SO2, LEL, CO2 or another gas?
2. How many gases need to be measured?
One or several?
3. Where will the detector be used?
Boiler, wastewater, manhole, tank, refrigeration plant, factory or another location?
4. How will the detector be used?
Personal monitoring, pre-entry testing, leak searching or area monitoring?
5. Do you need remote pump sampling?
Yes, no or not sure?
These answers make detector selection much easier.
Information to Send for a Quotation
Send MTM Precision:
Target Gas: If known
Application: Describe the job
Industry: If relevant
Required Range: If specified
Single or Multi Gas: If known
Personal Monitoring: Yes / No
Pre-Entry Testing: Yes / No
Pump Sampling: Yes / No / Not Sure
Quantity: Number of detectors
Calibration Requirement: If specified
You can also send a photo of the existing detector, datasheet, tender specification or consultant requirement.
OTYWELL G10S Gas Detector Supplier Malaysia
MTM Precision supplies the OTYWELL G10S single gas detector range for different industrial monitoring applications.
Available configurations include:
G10S-CO
CO: 0-1000 ppm
G10S-H2S
H2S: 0-100 ppm
G10S-O2
O2: 0-30% VOL
G10S-NH3
NH3: 0-100 ppm
G10S-SO2
SO2: 0-20 ppm
The correct gas detector should not be selected by price or appearance alone.
Start with:
Gas -> Application -> Range -> Number of Gases -> Sampling Method
Then select the detector.
Contact MTM Precision
MTM Precision Sdn. Bhd. (744811-A)
Telephone: +603-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com / enquiry@mtmpre.com.my
Website: www.mtmpre.com.my
Showroom & Service Centre:
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.
MTM Precision supplies gas detection and industrial testing equipment throughout Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Perlis, Terengganu, Sarawak and Sabah, Malaysia.
17 Sep 2026
