Eranntex MS104K-M Oxygen Alarm for Confined Space Safety Malaysia
Eranntex MS104K-M Oxygen Alarm for Confined Space Safety Malaysia
Oxygen is essential for breathing, but both insufficient and excessive oxygen can create serious workplace hazards.
An Eranntex MS104K-M portable multi-gas detector configured with an O₂ sensor can continuously measure oxygen concentration and warn workers when the level crosses the programmed alarm thresholds.
What Is the Normal Oxygen Level?
Fresh outdoor air normally contains approximately 20.9% oxygen by volume.
A reading that differs from the expected level may indicate:
Oxygen displacement
Oxygen consumption
Poor ventilation
Leakage of another gas
A combustion or oxidation process
An oxygen-enriched environment
Sensor or calibration problems
The required alarm limits should follow the workplace risk assessment, applicable procedure and regulatory requirements.
What Causes Oxygen Deficiency?
Oxygen levels may fall when another gas displaces the surrounding air.
Possible causes include:
Nitrogen purging
Carbon dioxide release
Argon or other inert gases
Methane accumulation
Refrigerant leakage
Process-gas leakage
Fermentation
Biological decomposition
Oxygen can also be consumed by:
Rusting
Combustion
Welding
Microbial activity
Chemical reactions
Workers breathing inside a poorly ventilated space
An atmosphere does not need to contain a known toxic gas to become dangerous.
Where Can Oxygen-Deficient Atmospheres Occur?
Potential locations include:
Storage tanks
Process vessels
Manholes
Sewers
Underground chambers
Silos
Ship compartments
Utility tunnels
Cold rooms
Nitrogen-purged areas
Wastewater facilities
Enclosed factory spaces
These environments should be assessed before entry according to the site’s confined-space procedure.
Why Oxygen Enrichment Is Also Dangerous
An oxygen-enriched atmosphere can make combustible materials ignite more easily and burn more rapidly.
Possible sources include:
Leaking oxygen cylinders
Damaged oxygen hoses
Medical or industrial oxygen systems
Incorrect purging
Process-equipment leakage
The oxygen sensor is therefore used to detect both low and high oxygen conditions.
What Does an O₂ Sensor Actually Measure?
The O₂ sensor measures oxygen concentration in the atmosphere around the detector or in a sample drawn through the pump system.
It does not identify:
Which gas displaced the oxygen
Whether a specific toxic gas is present
The concentration of an unknown inert gas
Every possible atmospheric hazard
For example, a reduced oxygen reading may indicate gas displacement, but additional sensors are required to identify gases such as CO₂, methane or nitrogen-related conditions.
Common Four-Gas Configuration
For general confined-space safety, the MS104K-M is often configured with:
O₂: Oxygen
EX: Combustible gas
CO: Carbon monoxide
H₂S: Hydrogen sulphide
This combination allows the instrument to monitor several common atmospheric hazards simultaneously.
However, specialised applications may require different gases and measuring ranges.
Testing Before Confined-Space Entry
The MS104K-M supports connection to an external pump for remote sampling.
Before entry, the operator can draw samples from:
The upper section
The middle section
The lower section
Areas near connected pipelines
Poorly ventilated corners
This allows the atmosphere to be checked while the operator remains outside the space.
Allow sufficient time for the sample to travel through the hose and for the reading to stabilise.
Why One Oxygen Reading Is Not Enough
Conditions inside a confined space can change because of:
Ventilation failure
Opening of a valve
Release of trapped gas
Disturbance of sludge
Welding or hot work
Introduction of cleaning chemicals
Entry of exhaust fumes
Ongoing biological activity
Continuous or repeated monitoring may be required during the work.
A safe reading before entry does not guarantee a safe atmosphere later.
What Should You Do When the Oxygen Alarm Activates?
If the detector produces an oxygen alarm:
Follow the site’s emergency procedure
Leave or do not enter the affected area
Do not ignore or silence the alarm
Inform the responsible supervisor
Investigate the cause from a safe location
Provide suitable ventilation where appropriate
Retest before allowing entry or work to continue
Never assume that the alarm is caused by a faulty sensor without first treating the atmosphere as potentially dangerous.
Why Does the O₂ Reading Change in Fresh Air?
Possible reasons include:
Sensor ageing
Incorrect fresh-air adjustment
Detector zeroed in contaminated air
Temperature or pressure changes
Humidity effects
Low battery
Sensor contamination
Calibration drift
Electronic or sensor fault
If the reading remains abnormal in known fresh air, the detector should undergo the required inspection, bump test and calibration.
Can You Zero the Detector Anywhere?
No.
Fresh-air adjustment must only be carried out in an atmosphere known to be clean and safe.
Zeroing in an oxygen-deficient or contaminated area may cause the detector to display misleading readings.
If clean air cannot be confirmed, use the correct zero-air procedure or seek technical guidance.
Bump Test and Calibration
A bump test verifies that the oxygen sensor and alarms respond when exposed to appropriate test gas.
Calibration verifies and adjusts the displayed measurement using certified reference gas.
The detector may require calibration after:
A failed bump test
Sensor replacement
Unstable readings
Physical damage
Long storage
Over-range exposure
Scheduled calibration expiry
A detector that fails testing should not be used for safety-critical work.
Oxygen Sensor Service Life
Oxygen sensors have a limited working life.
Actual service life depends on:
Sensor technology
Manufacturing and activation date
Frequency of use
Temperature and humidity
Exposure conditions
Storage
Calibration history
An old sensor may respond slowly, drift or fail calibration.
Sensor condition should be verified through testing rather than judged only by the detector’s external appearance.
Common Oxygen-Monitoring Mistakes
Avoid:
Assuming no smell means the air is safe
Monitoring oxygen without checking other identified gases
Testing only at the confined-space opening
Entering before completing pre-entry testing
Zeroing in an unknown atmosphere
Ignoring a small but persistent abnormal reading
Continuing work after an alarm
Skipping bump tests
Using an overdue calibration
Assuming ventilation eliminates the need for monitoring
The oxygen detector must be part of a complete safety system.
Is the MS104K-M Suitable for Your Application?
The MS104K-M may be suitable when you require:
Oxygen monitoring
Detection of up to three additional gases
Remote pump-suction sampling
Personal diffusion monitoring
Confined-space pre-entry checks
Multiple alarm methods
Data storage
Pump-blockage warning
The complete gas configuration should be selected according to the workplace hazards.
Why Choose MTM Precision?
MTM Precision supplies gas detectors, environmental monitoring instruments, industrial testing equipment and safety measurement solutions throughout Malaysia.
Our team can assist with:
Oxygen and multi-gas detector selection
Gas and measuring-range configuration
Confined-space application matching
Diffusion and pump-sampling requirements
Sampling accessories
Bump-test and calibration enquiries
Product quotation and availability
Basic operating guidance
After-sales and technical coordination
Request an Eranntex MS104K-M Quotation
Tell us:
Which gases need to be monitored
Required measuring ranges
Workplace and application
Confined-space requirements
Pump-sampling distance
Number of detectors
Required accessories
Calibration-document requirements
MTM Precision can help select an MS104K-M configuration based on the actual atmospheric hazards.
Contact MTM Precision
MTM Precision Sdn Bhd
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.
Website: www.mtmpre.com.my
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
We support customers throughout Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Perlis, Terengganu, Sabah and Sarawak.
14 Sep 2026
