Leak detector


Leak detector is used in bearing inspection and lubrication failure monitoring/mechanical fault diagnosis/condensing valve inspection/pressure and vacuum leak detection/leakage amplifier application/electrical partial or Arc discharge detection/heat exchanger, boiler and condenser/ultrasonic sound test, fire electrical discharge, bearing, gear, gearbox, engine, electric pump cavitation, motor, compressor, operating equipment and lubrication failure detection, ultrasonic sealing Destruction test, cargo box, weld seam, hatch, gasket, electrical equipment detection, electrical partial discharge (corona), high voltage arc, ignition, spark, leakage trace, insulation aging, power switch, transformer, relay, Circuit breaker, busbar/board, insulation device detection, heat exchanger, boiler and cooler, condenser, exhaust system, heating system, pressure test, pressure/vacuum, container, air, oxygen, nitrogen, refrigerant Leakage, valve/valve, hydraulic valve seat leakage or blockage detection, steam flap, steam dewatering gate, air pipe detection, mechanical fault diagnosis, ultrasonic sound test, car/aircraft/ship cabin sealing test, power transmission line detection, Long-distance inspection, pipeline and pipeline leak detection, general mechanical fault detection and elimination.

Leak detection serves all walks of life. As long as there is a leak in the environment, it is indispensable to detect potential hazards to achieve the effect of leak detection!

System application flexibility

The application flexibility of the system involves the detection method, detection medium, measurement system, operation method, automatic deviation correction function and expansion accessories of the equipment.

1. The detection method will directly affect the detection result. Choosing the detection method suitable for the product to be tested will maximize the detection effect.

2. The detection medium is preferably clean air with no pollution and low cost.

3. The measurement system will automatically help you complete the volume conversion.

4. Automatic deviation correction can effectively improve the detection accuracy and efficiency.

5. The extended accessory can help you connect to a computer and other equipment to track and analyze the data of the tested product.


1. Leakage inspection of tires and pipelines;

2. Leakage inspection of heating system;

3. Steam Internal leakage inspection;

4. Compressor air leakage inspection;

5. Refrigerator, air conditioning system, etc. leakage inspection;

6. Engine Leakage inspection of the seal;

7. Positioning measurement of the local discharge source of transformers, etc.;

8. Inspection of the bearings of motors and various machinery, etc.;

9. Detection of electrical discharge of switchgear, transformers, insulation devices, circuit breakers, relays, busbars, etc.;

10. Airtightness detection of airtight cabins;

11. The airtightness test of the whole car;

12. The air tightness evaluation and test of the room.

Working principle

Leak detector (mainly ultrasound-based SDT270 series imported from Belgium):

If a container or pipe is full When the internal pressure of the gas is stronger than the external pressure, due to the large pressure difference between the inside and the outside, once the container has a leak, the gas will rush out from the leak. When the size of the leak hole is small and the Reynolds number is high, the rushing gas will form turbulence, and the turbulence will generate a certain frequency of sound waves near the leak hole. The frequency of the sound wave vibration is related to the size of the leak hole. When the leak hole is large, the human ear The air leakage sound can be heard. When the leakage hole is small and the sound wave frequency is greater than 20kHz, the human ear can not hear it, but they can spread in the air and are called no-load ultrasonic waves. Ultrasound is a high-frequency and short-wave signal, and its intensity decays rapidly as the propagation distance increases. Ultrasound has directivity. Using this feature, you can determine the correct leak location.

Ultrasonic Leak Detector SDT is a leak detector with ultrasonic detection method, which can check the leakage of air, gas, vapor and liquid transportation pipelines and various equipment. If used in conjunction with the attached signal generator, it can also check the sealing conditions of refrigerators, sealed containers, air conditioning systems, tires, compressors, and various infusion pipelines. It is a powerful tool for improving the environment and saving energy.

With the ultrasonic signal generator, it can detect many environments.

Detection method

Pressure measurement method

In today's industrial airtightness inspection, pressure inspection is one of the most commonly used inspection methods. When the test volume is small, the leakage rate can be set from 0.1cc/min.

Based on the direct pressure detection method, the structure design of the test device can be made as compact as possible and the volume of the test system can be minimized as much as possible. In this way, higher working reliability can be obtained and a larger test range can be achieved. The resolution of the test signal depends on the level of the test pressure.

When the differential pressure method is used, because the resolution of the test signal has nothing to do with the level of the test pressure, under a higher test pressure, a higher test accuracy can be obtained than the direct pressure test method.

Using the pressure reduction method and under the overpressure of the tested workpiece, it can simulate the normal working conditions.

Based on the pressure increase method and the partial pressure test method, it can greatly suppress the influence of the temperature change and the instability of the volume caused by the plugging fixture or the workpiece, and its suppression effect is better than Pressure reduction method. When using the pressure increase method and working under overpressure, the balance phase in the test process can be omitted. In addition, the test pressure is not limited by the pressure range of the measuring components, the reason is that they have nothing to do with the test pressure.

Flow measurement method

In the pressure measurement method mentioned above, the larger the measured volume, the smaller the measurement signal will become; while in the flow method, the measurement signal It has nothing to do with the size of the measured volume. This is very convenient when calibrating the system. The flow signal in the flow method can directly reflect the amount of gas leakage set for calibration.

Generally speaking, the volume flow method (for example, through the pressure drop of a throttling element) can complete the leak test (small leak rate) and flow test (large leak rate) in the same test system. For example, when monitoring the fuel system passage, the instrument using the volume flow method has the same detection element (differential pressure sensor) to continuously detect the leakage of the other system by the pressure reduction method.

When the mass flow method (thermal measurement method) is used, the test signal is not only independent of the measurement volume, but also has nothing to do with the measurement pressure. The test signal will directly express the amount of leakage in the form of the standard unit of leakage rate cc/min, without the need to calculate the leakage rate (for example, pressure measurement).

Leak detection host technical parameters

Mainly refers to SDT/UE ultrasonic leak detector

Function: Multi-function detector

Display: High contrast, LCD with backlight display, 100×32 pixels

Keyboard: 8 function keys

Range: -10dBμV~120dBμV

Measurement resolution: 0.1 dBμV

Sensitivity: it can detect leaks with a pressure of 6psi, an aperture of 0.1mm, and a distance of 70 feet

Minimum limit: 1×10-2~1× 10-3std.cc/sec.FREON

Accuracy: ±0.5dBμV

Signal to noise ratio: -5dBμV typical

Bandwidth: (-3dB) 2kHz

Automatic shutdown: automatic shutdown at preset time

Working temperature: -15℃ to +60℃

Battery pack: 1.3 Ah rechargeable Ni-MH battery

Use 8~10 hours when the backlight is off

Charging time: 5~6 hours

Life span: 500~1000 charges/ Discharge cycle

Shell: rolled aluminum, rubber protective cover

Size: 203x38x88mm (LxHxW)

Weight: about 700 grams (including battery and leather case )

Resolution and accuracy

When purchasing leak detection equipment, resolution and accuracy are important factors. How to know the inspection capability of the equipment system requires understanding the following questions:

1. The resolution of the A/D converter does not represent the resolution of the system. When selecting the equipment, you will encounter the advertisement of 0.0001psi resolution, but you are not told that this resolution will only appear when the range is very small, and you may not be able to use it. The resolution of the system should be comprehensively given according to the range of the instrument.

2. The highest accuracy is not equal to the actual detection accuracy. The highest accuracy is often the result when the comprehensive factors (such as temperature, pressure, etc.) are in an ideal state. The comprehensive error should be considered in the actual test, and the accuracy of the instrument should be comprehensively given in the calibration certificate to meet the accuracy level of the national standard.

3. The detection rate is not fixed, but varies according to the volume of the test piece. If someone provides you with a detection rate without knowing what you are inspecting, then you should consider the credibility of the product.

4. Detection sensitivity depends on the entire system, including parts and detection specifications. If you encounter a promotion of 0.01CC/min, you should doubt that it may be able to achieve such a sensitivity in a specific environment, but it is extremely difficult to achieve in the actual detection process.

5. The final test result you should believe is the assessment result of the verification department. Only the suppliers who show you the certification of the authoritative department are truly trustworthy.

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