1、 Preparation before use

1. environment check
   • cleanlinessThe detection area should be free of strong winds, dust, or corrosive gases (such as acid mist, solvent vapor) to avoid contaminating the sensor or affecting detection sensitivity.
   • Temperature and humidity：
     • Helium mass spectrometer leak detector: It is recommended to control the ambient temperature between 10 ℃~35 ℃ and humidity ≤ 85% RH to prevent condensed water from entering the equipment.
     • Halogen leak detector: Avoid using it in high temperature (>40 ℃) or high humidity (>90% RH) environments, as it may trigger false alarms.
   • electromagnetic interferenceKeep away from strong electromagnetic sources such as frequency converters, motors, and radio transmitters. If necessary, use shielded cables or install filters.
2. Equipment inspection
   • Visual inspectionConfirm that the shell of the leak detector is not damaged, the interface is not loose, and the display screen or indicator light is normal.
   • Air source inspection：
     • Helium mass spectrometer leak detector: Check the pressure of the helium cylinder (usually ≥ 10MPa) to ensure stable gas supply; If using a helium recovery system, the recovery efficiency needs to be verified.
     • Halogen leak detector: Check the refrigerant (such as R134a, R22) or tracer gas (such as SF6) storage to avoid depletion midway.
   • Calibration verificationUse standard leak holes (such as 1 × 10 ⁻⁶ Pa · m ³/s) to verify the sensitivity of the leak detector, ensuring that the error is within the allowable range (such as ± 10%).
3. Preparation of the inspected item
   • Cleaning treatmentClean the surface of the test piece with oil-free compressed air or alcohol to remove oil, dust, or moisture, and prevent nozzle blockage or interference with testing.
   • pre-vacuumIf there is air inside the inspected part, it is necessary to first use a vacuum pump to pump it to the specified pressure (such as ≤ 10Pa), and then inject tracer gas (such as helium) to avoid diluting the tracer gas concentration with air.
   • Isolation treatmentClose all valves of the inspected item to ensure system sealing; If inspecting pipelines, blind plates need to be used to seal both ends.

2、 Precautions during the operation phase

1. Parameter Settings
   • Selection of detection mode：
     • Spray gun methodSuitable for local leak location, the spray gun needs to be aimed at the suspicious area (distance ≤ 5mm) and slowly moved for scanning.
     • Gun suction methodSuitable for closed cavity detection, the suction gun needs to be inserted into the interior of the inspected object to extract air and analyze the leakage rate.
     • 真空箱法Suitable for batch inspection of small items, the inspected items need to be placed in a vacuum box, vacuumed and injected with helium gas, and leakage detected through the box sensor.
   • Sensitivity adjustmentSet a threshold according to the leakage rate requirements (such as 1 × 10 ⁻⁹ Pa · m ³/s) to avoid false alarms or missed detections caused by excessively high sensitivity.
   • response timeSet an appropriate response time (such as 0.5-2 seconds) to balance detection speed and accuracy (fast response may increase noise interference).
2. Tracer gas usage
   • Helium concentration control：
     • Spray gun method: The recommended helium concentration is 5% -10%. A high concentration may cause detection saturation, while a low concentration may decrease sensitivity.
     • Vacuum box method: The helium injection pressure needs to be stable (such as 0.1-0.5 MPa) to avoid pressure fluctuations affecting the detection results.
   • Helium recoveryIf helium is used for a long time, a recovery system (such as membrane separation or low-temperature condensation) needs to be equipped to reduce usage costs.
   • Alternative gasIn helium shortage or cost sensitive scenarios, hydrogen (with explosion-proof devices installed) or nitrogen+tracer (such as Freon) can be used, but the sensitivity may be lower than helium.
3. Operating Specifications
   • Avoid cross contaminationWhen detecting different inspected items, it is necessary to blow the spray gun or suction gun with clean air to prevent residual tracer gas from interfering with subsequent testing.
   • Prevent mechanical damageHandle the leak detector gently during operation to avoid collision or falling; The spray gun head needs to be replaced regularly (such as every 500 inspections) to prevent wear and tear from affecting the uniformity of airflow.
   • data recordingReal time recording of leak location, leak rate, and detection time for easy traceability and analysis; If software linkage is used, it is necessary to ensure stable data transmission.

3、 Safety protection measures

1. Gas safety
   • Helium leakage treatmentAlthough helium is non-toxic, its high concentration may cause suffocation (oxygen concentration<19.5%). It should be used in a well ventilated environment and equipped with an oxygen concentration monitor.
   • Halogen gas protectionSome halogen gases (such as SF6) may decompose and produce toxic byproducts (such as hydrogen fluoride), so it is necessary to wear a gas mask or use a gas purification device.
   • Gas WarningIf hydrogen is used as a tracer gas, it should be kept away from sources of fire and static electricity, and equipped with an explosion-proof leak detector.
2. Electrical safety
   • grounding protectionEnsure that the leak detector is well grounded (grounding resistance<4 Ω) to prevent static electricity accumulation or lightning damage to the equipment.
   • Explosion proof designIn flammable and explosive environments such as chemical plants and gas stations, explosion-proof leak detectors (marked with Ex) should be selected and explosion-proof cables should be used.
   • Emergency stop deviceInstall an emergency stop button on the control panel to immediately cut off the power in case of an emergency.
3. personal protection
   • safety gogglesTo prevent eye injuries caused by spray gun backflow or high-pressure gas from helium cylinders.
   • Anti-static wrist strapWhen testing semiconductor or electronic components, it is necessary to wear an anti-static wristband to avoid electrostatic breakdown of sensitive devices.
   • protective glovesWhen operating high-temperature components (such as vacuum pump exhaust ports) or corrosive gases, it is necessary to wear heat-resistant or chemical resistant gloves.

4、 Maintenance and upkeep

1. Daily cleaning
   • Shell cleaningWipe the shell of the leak detector with a dry cloth to avoid using organic solvents (such as alcohol, acetone) to corrode the surface coating.
   • Spray gun/suction gun cleaningAfter each use, blow the inside of the spray gun with compressed air to prevent residual tracer gas or dust blockage.
   • Air inlet filtrationRegularly replace the air inlet filter (e.g. every 3 months) to prevent dust from entering the mass spectrometry chamber or sensor.
2. periodic calibration
   • internal calibrationConduct a comprehensive calibration every 6 months or 1 year (using standard leak holes and gas mixing devices) to verify sensitivity, linearity, and response time.
   • temperature compensationIf the ambient temperature changes significantly, it is necessary to calibrate separately at high and low temperatures and input the temperature compensation coefficient.
3. Replacement of vulnerable parts
   • Mass spectrometry chamber filamentThe filament life of a helium mass spectrometer leak detector is usually 500-1000 hours. If it displays "Filament Off" or signal attenuation, it needs to be replaced in a timely manner.
   • vacuum pump oilReplace the vacuum pump oil every 500 hours (if using Fomblin oil, it can be extended to 2000 hours) to prevent oil contamination from affecting pumping speed.
   • O-ringRegularly check whether the O-rings of each interface are aging or deformed. If cracks are found, they should be replaced immediately (usually every year).
4. Long term storage
   • clean and dryBefore being idle for a long time, clean the leak detector and wipe it dry to prevent rust or mold.
   • Gas source isolationClose the valve of the helium cylinder, discharge the residual gas in the pipeline, and avoid long-term deformation of the O-ring under pressure.
   • Storage environmentStore the leak detector in a dry (humidity<60% RH), ventilated, and non corrosive indoor environment, avoiding direct sunlight or high temperatures (such as>40 ℃).

5、 Common faults and troubleshooting

1. No signal or weak signal
   • reasonFilament breakage, mass spectrometry chamber contamination, and air inlet blockage.
   • processReplace the filament, clean the mass spectrometry chamber, and replace the intake filter element.
2. False or missed reporting
   • reasonImproper sensitivity setting, environmental interference, abnormal tracer gas concentration.
   • processRe calibrate sensitivity, stay away from electromagnetic sources, and adjust tracer gas concentration.
3. vacuum pump failure
   • reasonOil pollution, insufficient oil level, and motor damage.
   • processReplace the vacuum pump oil, replenish the oil, repair or replace the motor.
4. Software crash
   • reasonSystem crash, data overload, virus infection.
   • processRestart the device, clean up storage space, and install antivirus software.

6、 Special scenario precautions

1. High temperature environment detection
   • Choose a high-temperature resistant leak detector (such as a stainless steel shell material) and shorten the continuous working time (such as taking a 30 minute break every 2 hours).
   • Install a heat shield on the surface of the inspected item to prevent heat from being conducted to the leak detector sensor.
2. Strong corrosion environment testing
   • Choose an anti-corrosion leak detector (such as lined with polytetrafluoroethylene) and shorten the distance between the spray gun and the inspected object (such as ≤ 3mm) to reduce the contact time of corrosive gases.
   • Immediately rinse the spray gun with clean water and apply rust proof oil after testing.
3. Minor leakage detection
   • Use high sensitivity mode (such as 1 × 10 ⁻¹² Pa · m ³/s) and extend the detection time (such as detecting at each point for ≥ 5 seconds).
   • Cooperate with the building block method (dividing the inspected item into multiple small areas for individual detection) to improve positioning accuracy.

By strictly following the above precautions, the detection accuracy, stability, and service life of the Kelmer leak detector can be significantly improved, the failure rate can be reduced, and reliable guarantees can be provided for sealing testing. It is recommended to develop standardized operating procedures (SOPs) and have them executed by professionals or trained operators.