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Daily leak sensitivity checks and calibration

Leak testers and related products
Daily leak sensitivity checks and calibration
Pressure, flow meters and related topics

Q1.Why do leak sensitivity and other settings require daily checks?


Cosmo leak testers are designed to be reliable. For example, they are equipped with a self-check function which checks for any problems with valves and for decreased test pressure with each measurement (*1).However, if there was a mistake in the rearrangement or settings (alarm settings etc.), or if leak sensitivity has decreased for some reason, products which should be Fail could be misjudged as Pass.This kind of malfunction is extremely difficult to notice, so checks are required.
Be sure to check link sensitivity, not only at the start of the work day, but whenever the setup is rearranged or settings are changed.
(*1) The details of the self-check function differs according to the leak tester model.

Q2.What kind of devices are available for easily performing daily leak sensitivity checks?


There is a method of using a leak MASTER adjusted to cause a leak at a predetermined rate and another method of using a leak calibrator which can be set at will to cause a volumetric change appropriate for the leak rate.
The leak MASTER should be connected to the WORK measurement circuit and tested for leaks. The Pass/Fail judgment and the leak value displayed is used to check the sensitivity.
Leak calibrators could be of the ALC type, which operates due to pilot pressure built in to the leak tester, or be a hand-operated manual type.Manual types could be either a QLC type, which can cause volumetric change with a push of a button, or a LC type, which is set by turning a dial.


Q3.Which is more suited to daily checks—the leak MASTER or the leak calibrator?


The Leak MASTER and the leak calibrator both have their advantages.Choose the leak MASTER for simplicity and convenience of operation. Choose the leak calibrator for greater emphasis on stability after years of use and adaptability to many types of WORK.

Leak Master

Leak MASTER is easy to operate, and has the advantage of being easy to recognize because the leak rate (flow) is used as the standard.
The check can be made even more reliable by having one for leak sensitivity and another for checking settings.
However, there is a possibility that the leak value of the leak MASTER may change with time, after years of use. This must be routinely checked.The smaller the leak, the more important the management of its storage and leak value. (*1)

Leak Calibrator

Leak calibrator has the advantage of being superior in reproducibility, with next to no change of characteristics after years of use.
Also, since the value of volumetric change can be adjusted, it can be used in common for different test pressures and leak specifications, within a certain range.
Leak calibrators can be automatic—ALC type—or manual—QLC or LC types. The automatic ALC be mounted on some models but not on others.The manual QLC can cause volumetric change with just a push of a button, making it suitable for daily checks.
However, both leak calibrators require calculation to convert to the flow value which corresponds to the volumetric change. (*2)

(※1) A leak MASTER checker is available for checking the leak MASTER.
(※2) Some leak tester models calculate this automatically.

Q4.Can the leak MASTER or leak calibrator be connected easily?


In most cases, they connect to the calibration port on the front panel of the leak tester.(※1)
Some types of this port are connected directly to WORK’s side of the measurement circuit. Other types contain a valve (calibration valve) which can be controlled to open or close using a keyboard during the check. (※2)With the former, a sealing plug must be connected when a check is not being done to prevent leaks. This is not required with the latter.

(※1)To prevent hazards, calibration ports do not come on high pressure devices.
(※2)Leak testers with built-in ALCs do not have calibration valves built in. Also, calibration ports are used in checks using leak MASTERs.

Q5.What devices are necessary to show leak rate, not in differential pressure, but in flow units?


By using a leak MASTER or a leak calibrator, it can be displayed in flow units (applies only to models which have the flow unit display feature).
The volume equivalent K(Ve) must be found to change the differential pressure display to flow display. Leak MASTERs and leak calibrators are used as a way to obtain this volume equivalent.
The actual finding process is quite easy, using the K(Ve) calibration feature of the leak tester.
By setting the value of the volume equivalent K(Ve) in the tester, it becomes a tester with flow display.

Q6.When calibrating leaks, what is the difference between using a leak MASTER and using a leak calibrator or the like of the volumetric change method?


In most cases, there is no difference in the result of K(Ve) calibration.
However, there is a note of caution when using the volumetric change method.
When the volumetric capacity increases rapidly, adiabatic expansion causes the temperature to fall slightly. The effect of this temperature change causes a larger change than the (differential) pressure change due to volumetric change.The effect of the temperature gradually disappears and the extra differential pressure change also dissipates.
However, if the detection time is short, the effect still remains, and the measurement has a great inaccuracy.
There is no such effect with the leak MASTER.

Q7.Can the same calibrator be used for the daily checks and for leak calibration?


In case of leak MASTERs, we recommend preparing two separate dedicated ones.
For the check, keeping in mind measurement inaccuracies, a leak MASTER around 150% of the Fail judgment standard value is suitable.  (*1)
For leak calibration, a leak MASTER with a slightly high leak value results in a smaller noise ratio. We have prepared reference standards of a predefined leak value specifically for this purpose. (*2)
This leak MASTER comes with data of leak values at different points within a prescribed range of test pressures, and therefore can be used with versatility to some extent.
In case of leak calibrators, the volumetric change can be adjusted on QLC and LC types, so they can be used in both daily checks, such as for leak sensitivity, and for leak calibration. However, changing the settings on the ALC type involved input operations, so it is not suited for checking for mistakes in the settings, such as after a setup has been rearranged.

(※1)For general checks (produced with specified test pressure and leak rate)…LM-1C
(※2)For leak calibration…LM-1C-J

Q8.What is the difference between the calibrators?

Comparison of calibrators by testing conditions and uses
Calibrator type Leak-generating method Volume-changing method
Leak MASTER LM-1C Leak MASTER LM-1C-J Auto leak calibrator ALC Quick leak calibrator QLC Simple leak calibrator LC
(Can be used for different test pressures and leak specifications)
Simplicity and convenience(Ease of operation) X
(Value does not change over time)
Easy to understand(Ease of comprehension of theories and structure)
Durability(Can withstand high frequency of use)
Resistance to environment(Not affected by dirty air in the supply or the environment) X X
WORK test conditions Shortening of detection time
(Minimally affected by shortening)
High pressure specification (H15, H49)(Can be used at high test pressures) X X X
Uses Daily checks Leak sensitivity check
Setting check X X
リLeak calibration
(Suitable for measuring the flow coefficient)
Price Catalog price\38,000
Catalog price\38,000
Included in the price of the tester Catalog \35,000
  • ◎;Very good
  • ○;Good
  • △;OK, or yes and no
  • ×;Bad