Why Does a Combustible Gas Detector Alarm Even When You Cannot Find a Leak Malaysia
Why Does a Combustible Gas Detector Alarm Even When You Cannot Find a Leak Malaysia
You switch on a combustible gas detector, approach a pipe or machine, and the detector begins to alarm.
But after checking the area, you still cannot identify an obvious gas leak.
Does this mean the detector is faulty?
Not necessarily.
Portable combustible gas detectors such as the TASI TA702A and TA702B use sensitive sensors designed to respond to combustible gases and vapours. Detector response can therefore be influenced by the gas concentration, surrounding environment, sensitivity setting and other combustible vapours.
Understanding these factors can make gas leak troubleshooting more effective.
1. Sensitivity May Be Set Too High
High sensitivity is useful when initially searching for a possible leak.
However, once the detector begins responding, staying at the highest sensitivity may make it difficult to determine the exact source.
This is where the TASI TA702A High / Medium / Low sensitivity adjustment becomes useful.
A practical approach is:
High Sensitivity → Find the General Area
Then:
Medium Sensitivity → Narrow the Search
Then, where appropriate:
Lower Sensitivity → Investigate the Suspected Point
The objective is not simply to make the detector alarm.
The objective is to identify where the detector response becomes strongest and most repeatable.
2. Combustible Vapour May Be Present Nearby
A combustible gas detector may respond to more than one combustible substance.
The TA702 Series can respond to combustible gases and vapours including examples such as:
Methane
Propane
Ethanol
Gasoline vapours
Therefore, an alarm does not automatically prove that the exact gas you suspect is leaking.
For example, combustible vapours from another nearby source may influence the detector response.
Always consider the surrounding environment.
3. You May Be Detecting Gas Away from the Actual Leak Point
Gas does not necessarily remain exactly where it escapes.
Air movement can carry gas or vapour away from the original source.
As a result, a detector may respond at one position even though the actual leakage point is somewhere nearby.
Instead of assuming the first alarm location is the leak source, inspect systematically.
For example:
Pipe → Joint → Valve → Regulator → Hose → Equipment Connection
Compare how the detector responds at each point.
4. Air Movement Can Affect Leak Tracing
Fans, ventilation systems, extraction systems, open doors and other airflow can influence where gas or vapour travels.
This can make leak locating more difficult.
A technician should therefore consider the ventilation conditions when interpreting detector response.
The strongest reading in open air does not always correspond directly to the physical leakage point.
Follow the appropriate site safety procedure when investigating suspected gas leakage.
5. The Sensor May Need Time to Stabilize
Portable gas detectors should be operated according to the manufacturer's startup and operating instructions.
Immediately beginning an inspection before the instrument is ready can lead to confusing results.
Allow the detector to complete the required startup or warm-up process before relying on its response.
Do not assume that switching the instrument on means it is instantly ready for accurate troubleshooting.
6. The Probe May Be Too Far from the Suspected Connection
Small gas leaks may require the sensing area to be positioned close to the suspected source.
This is why the flexible probe on the TASI TA702 Series is useful.
Instead of checking only the general area around a machine, move the probe carefully around individual:
Pipe joints
Valve connections
Regulators
Fittings
Hose connections
Equipment connections
A systematic point-by-point inspection is usually more useful than randomly moving the detector through the air.
7. A Strong Alarm Does Not Automatically Identify the Gas
A combustible gas detector responds to combustible substances within its sensor capabilities.
It is not necessarily identifying the exact chemical compound that caused the response.
This distinction is important.
If a detector responds in an area containing several possible combustible vapours, additional investigation may be required to determine the actual source.
Do not interpret every alarm as:
“This is definitely methane.”
or
“This is definitely LPG.”
without considering the application and environment.
8. Check Whether the Response Is Repeatable
When troubleshooting, repeatability can provide useful information.
For example:
Move the detector away from the suspected location.
Then carefully approach the same point again.
If the detector repeatedly produces a stronger response around the same connection, that area deserves further investigation.
If the response appears randomly throughout the surrounding area, consider environmental influences and other combustible vapour sources.
9. TA702B Can Help Show Concentration Changes
The TASI TA702B provides additional indication including ppm / LEL and concentration trend information.
This can help technicians compare detector response while moving between different inspection points.
For example:
Point A → Low Response
Point B → Increasing Response
Point C → Stronger Response
This information can assist troubleshooting.
However, displayed concentration should always be interpreted according to the instrument's specifications and intended use.
10. When Should You Suspect an Instrument Problem?
If the detector behaves abnormally even after following the correct startup and inspection procedure, further checking may be required.
Possible warning signs include:
No response where a response is expected during an appropriate functional check
Continuous abnormal alarm behaviour
Unstable indication under consistent conditions
Physical damage to the probe or instrument
Battery or charging problems
Sensor performance that appears inconsistent
Follow the manufacturer's instructions for inspection, testing and servicing.
Do not intentionally expose a detector to an uncontrolled gas source simply to see whether it works.
Gas Detector Alarm Does Not Always Mean Instrument Failure
When a combustible gas detector alarms but the leak source is not immediately obvious, consider:
Sensitivity → Other Combustible Vapours → Airflow → Probe Position → Startup Condition → Inspection Technique
A sensitive detector is useful only when the operator understands how to interpret its response.
For maintenance technicians, systematic troubleshooting is more effective than simply searching for the highest number or loudest alarm.
Need Help with a Combustible Gas Detector in Malaysia?
MTM Precision supplies test and measurement instruments for factory maintenance, facility management, commercial kitchens, industrial troubleshooting and gas leak inspection.
If you are unsure whether the problem is the detector, the application or the inspection method, tell us:
Detector model
Gas being checked
Application
Where the alarm occurs
Whether the alarm is continuous or only at certain locations
This information can help identify the next troubleshooting step.
MTM Precision Sdn Bhd
Showroom & Service Centre
No 29-1 & 2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor.
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my
Serving customers throughout Malaysia including Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kelantan, Terengganu, Kedah, Perlis, Sabah and Sarawak.
27 Sep 2026
