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• Automatic tests are made possible, requiring less manpower compared to water-dunk tests.WORK does not get soiled, since no liquid is used.
• The test standard can be quantified, eliminating products overlooked by human misjudgment.
• Tests of high precision can be performed in a short time. The running cost is low, helping to cut costs.

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1 atm·mL/s or atm·mL/min The volume of air leaking into the atmosphere per second or per minute. “atm·” is often omitted.
1 μgr/s or μgr/min The weight of air leaking into the atmosphere per second or per minute.
1 μgr (microgram) => 0.83 × 10 − 3 mL (at 1 atm, 20°C)
1 Lusec A leak rate of an increase in pressure of 1 µHg per second in a vacuum chamber of 1 L.
1 Lusec = 1/760 mL/sec ≃ 1.32 × 10 − 3 mL/s
1 Torr·L/s A leak rate of an increase in pressure of 1 Torr per second in a vacuum chamber of 1 L.
1 Torr･L/s=1000 Lusec≒1.32 mL/s
1 Pa･m³/s
1 Pa･ m³/s = 9.869 atm mL/s
1atm･mL/s = 1.013 × 10^-1Pa･m³/s

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During the stabilization or detection stage, the differential pressure ΔP is calculated according to the equation below after auto-zero is performed, and the leak rate is displayed in its unit (mL/s or mL/min).

Ｑ：Leak rate (mL/s)
Ｋ(Ve)：Volume equivalent (mL)
ΔＰ：Differential pressure (Pa)
ΔＴ：Time (s)
If the leak rate does not change and remains constant during the detection stage, no additional detection time is required, and the testing time could also be shortened.

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(1)Volume equivalent

The amount of differential pressure due to leaks depends on the internal volume of the measuring system as a whole, including WORK and the tester.This also strongly related to measurement time.
With air leak testers, we use as this internal volume a coefficient called volume equivalent (Ve), which accounts for the effects of causes for pressure change throughout the measuring system as a whole (volumetric changes due to the internal pressures of WORK or the differential pressure sensor).等The volume equivalent can be calculated using the following equation.With the air leak tester LS-1842 series, the auto leak calibrator (ALC) or the leak MASTER can be used to measure the value of Ve directly.。
Ve=Vw+Vt+｛Ks(1+Vw/Vm)+Kw}(101.3+P)
Ve：Volume equivalent (mL)
Vw：Internal volume of WORK and tubing (mL)
Vt：Internal volume of tester (mL) Vt = 9 mL
Ks：The ratio of volumetric change of the sensor per pressure unit (mL / kPa)
Kw：The ratio of volumetric change of WORK per pressure unit
P：Test pressure (kPa)

Under conditions
Ks(1+Vw/Vm)+Kw=2Ks
l Ks＝0.01ｍL/ｋPa above
Ve=Vw+Vt+0.02（101.3+P）
l Ks=0.005mL/ｋPa above
Ve=Vw+Vt+0.01（101.3+P）

(2)Leak rate

The relational expression for volume equivalent and leak rate Q

Q ：Leak rate (mL / min)
ΔP：Differential pressure (Pa)
Ve：Volume equivalent (mL)
T：Detection time (s)

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Finding pressurization and stabilization time
When setting the measurement time while performing experiments or startup adjustments, confirm first that there are definitely no leaks in WORK or the toolings. Then, start with ample pressurization time to obtain data.
Gradually shorten this time and find the shortest pressurization and stabilization times where data is stable around zero.
Guidelines:
For Intelligent 1 Pneumatic Circuit（対象リークテスター型式：　LS-1866、LS-R700など）
Pressurization time (CHG) to Stabilization time (BAL) = 3 to 1 or 4 to 1

For Intelligent 2 Pneumatic Circuit（対象リークテスター型式：　LS-1881、LS-R900、LS-R700など）
Pressurization time (CHG) to Stabilization1 (BAL1) to Stabilization2 (BAL2) = 5 to 5 to 1
Note: When WORK volumetric capacity is low, pressure equalizing time is not required.Set BAL1 to 0 seconds.
These times usually depend on the condition of the actual machinery, equipment, and tooling, as well as the characteristics of WORK, and therefore must be found by experimentation.They can also be estimated for WORK which have been used in the past.

Required pressurization and stabilization time (Pressurization time CHG + Stabilization BAL) ↓

Low pressure <- Test pressure -> High pressure

※The above graph does not include detection time.
※Time can also change depending on the precision required.

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We have a product Leak MASTER LM-1C (Patents No. 2042571, 2042578).

• It causes a constant leak accurately for a long period, stably.
• This allows for issue of a traceability certificate.
• It can be installed directly into the CAL port on the front surface of the tester. (May not be possible on some tester models)
• When installing on WORK tubing, use the included adapter (connection R1/8—M10 × 1.5).It can easily replace a sealing plug.
• When ordering, specify the ranges of test pressure and leak rate below.
• Test Pressure:  1 kPa to 0.5 MPa, −13 kPa to −53 kPa
• Leak rate: 0.1 to 20 mL/min
• We accept special custom orders.
• Flow data for each pressure point is attached, and can be used, for example, to find the volume equivalent and to check the leak coefficient (K).

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(1)Theory and structure

（(In the MASTER comparison method, a Pass product without leaks is used as MASTER. The MASTER chamber is used in place of that MASTER.)
When WORK is pressurized, the temperature of the air inside it rapidly increases, but decreases as it exchanges heat with the interior surface of WORK.The characteristics of the temperature in this situation are greatly affected by the ratio of the internal volume to surface area. The greater the surface area, the temperature stabilizes more quickly, as does pressure.When MASTER detects differential pressure between it and WORK, this works to negate the change in pressure which arises from this decreasing curve in temperature.
The number and arrangement of fins can be changed inside the MASTER chamber to change the volumetric capacity and surface area, to match the decreasing curve in temperature with that of WORK.

(2)The advantages of using a MASTER chamber

• It can be adjusted to the characteristics of WORK.
• It does not take up much space.
• It costs less than using WORK to make MASTER.
• It has a O-ring seal, so it can be used without worry against leaks for a long period of time.
• Coupled with mastering and automatic drift correction, one MASTER chamber can work with many different WORKs.

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Try using an external exhaust valve. This is a sample external exhaust valve.

• When small amounts of water, oil, or similar substances are left inside WORK or when it is used in a testing device which is used in combination with water-dunking, such foreign matter could be blown from WORK into the tester with the exhaust and cause malfunction.Such malfunction can be prevented.by setting up this exhaust valve unit close to WORK.
• It uses a special air-operated valve with a structure which is resistant also to solid waste.
• The movement of the exhaust valve can be controlled by the tester body.