NAKK Leak Tester : Japanese Advanced Leak Tester Specialist


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As a specialist in the manufacture and development of leak testing devices (leak tester, leak detector) and other industrial measurement devices, couplers and power saving & automation devices, NAKK has contributed greatly to the quality control and improvement programs of various industries for more than fifty five decades.

Quick Delivery and Low Cost through In-House Development

We develop high-quality leak testers in-house at our own factory. We are a retailer and distributor, so we are different from other large companies that cannot offer flexible services. In addition, we can design and create all kinds of leak test devices and leak tests based on your specific requirements and needs. Another advantage of developing our products in-house is that we can greatly increase the speed and turnover of our products at a much lower cost. If you would like to learn more about what we can do for your company, feel free to contact us. We would be happy to discuss a customized plan for you.

Speedy and Accurate Customer Support

One of the reasons NAKK is one of the best choices for leak testing equipment is our knowledgeable staff. We handle everything in-house and ensure that all inquiries are answered appropriately.*Please contact us by e-mail as there are no staff who can speak English.

We develop Leak Tester by our own technology

NAKK takes pride in developing many technologies, such as a new leak test method called differential pressure secondary measurement method (patented) to solve the problems of conventional leak testers. This new method enables stable inspection.Also, in the “work comparison method”, there was a problem that the pressure difference could not be determined if there was a leak in both works.The differential pressure secondary measurement method can determine the pressure difference by measuring twice.

NAKK Leak Tester Features


Sealing jig is essential to the automation of leakage inspection. Leakage can not be measured with high sensitivity without sealing and measuring method. We can design and produce jigs according to your work.


You can choose the appropriate type of device according to your requirements.


Its highly-sensitive sensor and specially-designed piping system make leakage inspection ultra-sensitive and fast.


It is compact in size that saves space and makes it easy to incorporate into automated machines.


It allows the user to freely sets the standard for test pressure, test duration and leakage determination.


Its capability of displaying the level of leakage on indicating device allows user to easily determine the amount of leakage through the use of conversion or tables/graphs.


Since Leak Tester has input and output outlets that allow connection with external devices to receive activation signal and send signals to tells the rejects/non-rejects and the completion of inspection, it can easily be connected to automatic feeding jig and automatic segregation device to be incorporated into mass production line as fully-automated machine.

Problems in the Older Version of Leak Tester (Leakage Inspection)

While inspection Is conducted using Leak Tester (leakage inspection), there may be a case when accurate measurement can not be achieved due to noise. “Difference in temperature” and “Change in volume” are some of the factors that may generate major physical noise.


In case of work that is thin, wide surface area and higher heat conductivity, the pressure inside the pressure difference sensor changes due to the occurrence of volume changes caused by the difference in temperature. The volume increases as temperature rises while the volume decreases as temperature decreases and therefore, the change of pressure can not be detected correctly.
Works that are prone to noise that is generated by the difference in temperature: Pipe, aluminum, radiator, etc.


Some works expand or contract when pressure was applied into them for inspection. In such case, leak tester is unable to detect the correct pressure change due to change in volume.
Works that are prone to noise that is generated by the difference in volume: Pet bottle, container made of resin, flexible hose, etc.
Such noises can not be avoided by the old Pressure Difference-Type Leak Tester (leakage inspection). Also, even if “Work Comparison Method” is used to avoid the change in temperature, there is still a problem where pressure difference can not be identified when both works has a leak.

The Industry’s First “Work Comparison secondary Measurement Method (patented) ” Solution

In order to resolve the problems in the old version of leak tester (leakage inspection), NAKK has developed a leak tester (leakage inspection) that adopts the new method called “Work Comparison Secondary Measurement Method”. Since it measures the same works using “Work Comparison Method”, the effects from change in temperature and volume are very minimal and therefore, stable inspection can be performed.
Problem in “Work Comparison Method”, which the pressure difference can not be identified when both works has a leak, has also been resolved by the implementation of secondary measurement.

Corporate Profile


Main Office/ Factory〒193-0821
838-3 Kawa-Machi, Hachioji-Shi, Tokyo
Capital15,300,000 Yen
Sales Office〒483-8332
224, Hidakachokadono, Konan-shi, Aichi
Products1. Air leak tester (airtightness inspection device) Design, manufacture and sale of inspection device for leak test and pressure/flow measurement device
2. Digital pressure gauge
3. Indentation tester, tensile tester
4.Various devices


July 1961The first representative director, Taishi Nakamura, established Nihon Automation Kiki as a manufacturing and sales company for automatic control devices such as pneumatic solenoid valves and cylinders.
December 1965Started development of seismic safety device
April 1968Developed and started sales of leak testers
September 1981Developed eddy current prevention (Nucky) for propane gas cylinders as seismic safety equipment, increased capital and started production and sales.
October 1981Development of leak tester for cooling water used in nuclear power plants
September 1982Renamed to Nakk Co., Ltd.
November 1982Started development and sales of popular leak testers
June 1991Microcomputer-type leak tester developed
November 1991Developed a leak tester for faucet fittings
June 1996Developed a “patented” differential pressure secondary measurement type leak tester
April 1997Hiroyuki Nakamura, 2nd generation, appointed as Representative Director
July 1998Developed a low-cost microcomputer-type leak tester
December 1998Development of leak test equipment for ice molds
December 1999Website opened
April 2003Established a sales office in Komaki City, Aichi Prefecture
October 2003Sales of digital pressure gauge NDP-6000 series
April 2008Established the second factory in Kawaguchi-cho, Hachioji-shi, Tokyo
April 2009Established a leak test laboratory at the second factory
June 2009Temperature compensation system patent acquired
August 2009Developed desktop leak tester NT-700 for small parts
July 2012Concluded an agency contract with MNS Automation in India.
July 2013Moved to Kawamachi, Hachioji City, Tokyo, and consolidated the second factory
Aplil 20143rd generation Tomoya Nakamura Appointed as Representative Director
May 2016Concluded an agency agreement with Pines in South Korea.
September 2017Moved sales office from Komaki City, Aichi Prefecture to Konan City
April 2019Launched differential pressure type low cost leak tester NLT-360
Released air flow tester NFT-720
Launched differential pressure type leak tester NLT-720
October 2021Development and sales of indentation tester foot pump type and electro-hydraulic type
November 2022Developed leak test equipment with 6-axis robot


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