Q&A: The higher the precision, the easier it is to misjudge? Uncovering the real stability logic of production line airtightness testing

As a source manufacturer in the field of airtightness testing and quality engineering for 17 years, JCGK has seen too many factories pursuing the "airtightness test" for the sake of "quality".Extreme Precision" and choose the wrong equipment.

Today I want to tell you a very real truth:Those 0.02% F.S. high-precision parameters that strike you at first glance may well be the most sophisticated traps in the industry!The

Official nominal accuracy & cost tables for the world's top pressure sensor brands:

Precision echelon	True Accuracy	Branding	Estimated cost (¥)	Marginal notes
Metrological/laboratory grade	0.008%~0.02%F.	Paroscientific	40000~80000+	The cost of a single piece is higher than that of the whole machine of ordinary domestic hermetic tester.
		Mensor/WIKA	15000~30000	Sensor Module for High-Level Calibration
High-end industrial/aerospace grade	0.025%~0.05%F.	Rosemount 3051S	8000~20000	High-end industrial process standard
		Honeywell PPT2	4000~10000	Intelligent Temperature Compensation Sensor
OEM On-Board Chip Level	Less than 0.02%F.	Precision MEAS/TE	600~1000	24-bit ADC chip, easily advertised by stealing concepts

Mid-range of the marketairtightness leak detectorIt's impossible to install a metrological grade sensor that costs tens of thousands of dollars.

I. Three worlds, three perceptions

When we talk aboutaccurate"At the time, there was a clear cognitive stratification in the industry

airtightness leak detectorSelection tutorial: avoid getting caught up in meaningless parameter involution

Tier 1: Parameter Definers(The Few Who See Through)

This type of engineer doesn't look at the marketing speak and only cares about thePhysical Limits and Measurement ModelsThe

They're very clear:

• "% F.S." butFull scale errorLimited practical reference value
• resolution (of a photo)decide whether or not"Catching" tiny leaks
• repeatableDecide whether or not you can.Stabilization" pass or fail

For them.Accuracy is not a number, but a complete system of measurement capabilitiesThe

Tier 2: Rational Users(People who start to question)

This type of user already understands:

• 0.1% F.S. does not represent true-high accuracy.
• Differential pressure method is overall better than direct pressure method
• Measured stability is far more important than nominal parameters

They do:

• Carefully compare the parameter sheets of different brands
• Require suppliers to provide on-site prototype testing
• A rational trade-off between cost-effectiveness and performance

They are close to the truth, only one core perception is missing:Accuracy never equals full detection capabilityThe

Tier 3: People Surrounded by Marketing(Most of the easiest to step on)

This is the most common phenomenon in the industry:

• by "0.02% F.S.The eye-catching parameters of the "Battle of the Bands" attract
• Simply assume that the smaller the value the better
• Completely ignore environmental impact, tooling design, algorithm optimization

Final Results:
Paying a high price for a device with 'beautiful parameters'I'm not sure what I'm talking about, but I'm talking about the production line.Drifting data, many misjudgments, frequent reworkThe

II. The truth about precision - five neglected determinants

You can putairtightness leak detectorThink of it as aHe who listens to the sound of leaks」：It's good for the ears alone.(Sensors)Far from it, but also the environment is quiet, the work equipment is sealed, the judgment logic is reliable, in order to measure the real resultsThe

Factor 1: Sensor Accuracy(Ceiling of theoretical capacity)

The sensor determines the systemTheoretically, how subtle a change can be discernedThe

Common accuracy intervals:

• Mid-range equipment: ±1%% F.S.
• High-end devices: 0.1% ~ 0.2% F.S.

The Brutal Truth About the Industry:
The vast majority of sensors do not meet the 0.02% F.S. level on their own.. Much of the ultra-high precision that is advertised is essentiallyParameter patchwork, not real realizable capabilitiesThe

Brand name	Core Model	Accuracy/Resolution	Core findings
France Adeche ATEQ	F620	Compound error: ±(1% Rdg + 1 Pa) Display resolution: 0.1 Pa (500 Pa range)	Adopting scientific reading+noise labeling system, objectively reflecting the physical real boundary, not claiming 0.02%F.S. System accuracy
Japan Cosmo	LS-R700	Detection resolution: 1 Pa (core); special models up to 0.1 Pa	Extremely high stability thanks to intelligent air paths and precise calibration, with resolution focused on engineering practical values.
China JCGK	JC-C10005	Differential pressure accuracy 0.075%F.S.; display resolution: 0.01Pa, 0.001ml/min	Push resolution to the limits of engineering with intelligent air paths and precise calibration for extreme stability.

Well-known on the marketairtightness leak detectorParameter list of representative models of the brand

Factor 2: Manifold Seal Stability(Key to being grossly underestimated)

If you compare the inspection system to a pipeline, the valve manifold is a "pipeline".Switching valves".

A direct consequence of an unstable seal:

• The device itself has micro leaks
• Continuous drift of measurement data
• The end result is completely distorted

There is no more embarrassing situation:The instrument itself "leaks" before the product is measured.The

Factor 3: Ambient temperature(unseen interference killer)

It is a fundamental law of physics that gases are extremely sensitive to temperature:

• Temperature rises → Pressure rises
• Temperature fluctuation → false leakage signal appears

It's like measuring the size of a balloon in hot air, the reading keeps changing, but the balloon itself isn't leaking at all.

Real Case:
An automotive parts plant inspection line has a 40% higher false positive rate in the summer than in the winter.The root cause is unstable temperature control in the workshopThe

Factor 4: Tooling(The most overlooked link)

This is the hardest hit area with the highest incidence of miscarriages of justice:

• Poor sealing surface fit → direct false leakage
• Deformation of fixture structure → Continuous data drift
• Insufficient positioning accuracy → Very poor repeatability

Many of the so-called "product quality problems" are actually "fixture leakage"The
set pattern of behaviorPoorly designed workwearcanMake high-end equipment perform less well than ordinary equipment with high-quality workholdingThe

Factor 5: Software algorithms(Core for determining the upper limit of the system)

The algorithm is the brain of the system and directly determines the final detection limitThe

Core competencies include:

• Temperature compensation algorithm
• Noise filtering mechanism
• Intelligent decision logic
• Data traceability and analysis

The measured data show that:
With the same set of hardware and different algorithm optimization, the actual accuracy difference can be as high as3~10 timesThe

III. Professional assessment - two non-skippable validation steps

Step 1: Standard calibration

goal: Verify that the instrument is operating properly within the standard accuracy range.

methodologies: Periodic calibration using a standard leakage source.

It's like getting a vision test, not to prove how good your eyesight is, but to first confirm that your measurement baseline itself is reliable.

Step 2: Repeatability testing

Test Methods::

1. Selection of the same standard parts
2. Continuous test ≥ 5 times
3. Record the range of data fluctuations for each

Qualifying standards::
The fluctuation range should be kept within ±1% rdg Inside.

Even a high nominal accuracy means nothing if the repeatability is not up to standard. Like a ruler that reads differently every time you measure the same object, the ruler is a waste product.

IV. The Biggest Myth - Why Higher Accuracy May Not Be Right for You

Misconception: Pursuing Ultimate Precision

Many procurement and engineering staff are stuck in a fixed mindset:

• The highest accuracy of helium detection is always the best
• The smaller the parameter number, the more advanced the equipment
• Imported equipment is naturally superior to domestic equipment

Correct cognition: matching needs is the core

To use a very blunt analogy at a glance:

Testing needs	The right tool for the job	Unsuitable tools
Find the Bucket Loophole	Flashlight + Water	electron microscope
Check for chip defects	electron microscope	ordinary magnifying glass

You certainly wouldn't use an electron microscope to find a bucket crack because:

1. A great waste of cost for a great deal of material
2. Complicated operation and low productivity
3. Harsh environmental requirements and troublesome post maintenance

airtightness meterSelection, exactly the same logic.

Real-world examples: the true cost of over-precision

A 3C electronic factory introduced a set of imported equipment with an accuracy of 0.1% F.S. to test the waterproofing of cell phone cases.

Status after three months:

• Maintenance costs of equipment exceeded the budget by 3 times
• Additional modifications to the production line to meet environmental requirements
• The false positive rate is higher than the original domestic equipment

Root Cause:
The waterproof standard of the product is only 0.2% F.S. Accuracy is enough, too high accuracy rather amplify the environmental interference, so that the detection is more unstable.

V. Practical selection - how to choose the right oneAirtightness Tester

Principle 1: Look at the "reading error", not just the full scale error.

Prioritize from highest to lowest:
1️⃣ %rdg(reading error)-- the core, the real
2️⃣ Repeatability(Repeatability)-- directly determines stability
3️⃣ Resolution(resolution)-- Determine whether microleakage can be detected
4️⃣ %F.(Full scale error)-- for information only, of limited significance

Principle 2: Look at the "system capability", not the single point of beautiful parameters.

The five links must be assessed as a whole; a weak link is a weak whole:

Sensor Performance
    ↓
Manifold sealing
    ↓
Tooling Design
    ↓
Environmental adaptability
    ↓
Software algorithm optimization

Any shortcoming can become a bottleneck for the entire inspection line.

Principle 3: Look at the "production line performance" and do not believe in laboratory data.

Ask only three core questions before placing an order:

1. Is it stable?
   What is the range of data fluctuation for 72 hours of continuous operation?
2. Are there many misjudgments?
   Can the actual production line misjudgment rate be stabilized within 1%?
3. Is it durable?
   How much does the performance decay after a year of operation?

These three answers are more credible than any list of parameters.

VI. The Reality of Domestic Substitution - Technology Catch-up and Market Choices

Imported vs. national equipment: real capacity comparison

Imported equipment advantage:

• Deep brand accumulation and high market recognition
• Long technology iteration time and solid foundation
• Relatively mature global service system

Domestic equipment breakthrough point:

• System integration capabilities are improving by leaps and bounds
• Outstanding price/performance advantage
• Faster customization and service response

Core competencies of home-grown programs

Today more and more factories have seen the light:
The real gap is not in the parameters, but in the "system engineering capability".The

in order toJingcheng Gongke (JCGK)Domestic head manufacturers represented byThe core strengths are clear at a glance:

capability dimension	concrete expression
Multiple detection methods	Positive / Negative / Differential / Volume / Flow and other mainstream principles are covered.
Line Integration Capabilities	Provide complete automated inspection solutions
responsiveness	Local team, fast on-site commissioning and repair
Industry experience	New Energy / Automotive / 3C Electronics / Security Lighting / Medical Devices and other in-depth landing cases

in order toShenzhen Jingchenggongke Technology Co., Ltd.The value of the industry solution-oriented vendors represented by the company has never been "thecheaper", rather:

With a more reasonable cost, to achieve close to or even replace the imported stability performance

A Pragmatic Choice Proposal

Keep these points in mind when selecting equipment:
✔ Don't get carried away by "0.02% F.S.".
First distinguish whether it is %F.S. or %rdg, and whether it is a sensor parameter or a complete system parameter.

✔ Be sure to sample and test on site
Test with your product, in your production line environment, and the results will be most convincing.

✔ Prioritize manufacturers who understand production lines
Suppliers don't just sell equipment, they understand your process and pain points.

✔ Look at the total solution, not just the individual machine
Industrial design, software docking, after-sales protection, the lack of one.

Conclusion

In the airtightness testing industry, the numbers on the parameter list are never the whole truth. It is the systematic engineering of sensors, valve manifolds, tooling, environment and algorithms that really determines the testing capability. The key to choosing the right equipment is not to chase the highest precision, but to find the solution that best matches your production line.

Original Statement: This article was written byShenzhen Jingchenggongke Technology Co., Ltd.Written by the technical team, reproduced with attribution.Data sources: Precision Engineering internal test data and customer cases.