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Differential pressure volume testing provides accurate measuring results and can be easily integrated into most automated systems.
Compressed air is used as test medium resulting in low operating costs and freedom from contamination.
Cleaning and drying of previously tested parts, as well as corrosion protection, is not required.


Automation of the workplace nowadays have to be realized even in quality assurance and the equipment used. To test production parts for volume, it is necessary to integrate the leak test in the manufacturing process.
Important features of the VOLUME TESTER 3925-0360 are:


    • automatic control cycle
    • storage of test programs
    • contamination free test
    • reproducible measuring results
    • short cycle times with high accuracy
    • unambiguous results
    • measured value display
    • programmable test pressures and test times to suit testing to the production of many different components
    • user friendly operation with interactive user guidance
    • modular design concept for ease of maintenance and service

Operating principle

The operating principle is based on the interdependence of the state variables volume, pressure and temperature. The definition can be deduced by the ideal gas law.

Determination of the volume difference in 2 locked volumes within a given measuring time.
A differential pressure measuring sensor serves as transducer (to reduce the dependency on variations of the filling pressure).
A volume (comparison volume) corresponds to the master volume.




Programming of the control and test parameters is menu guided - no special knowledge is required. The test parameters in the program register and can be recalled as required. Different selectable languages are available.

A write-protect key switch ensures data security. Data can be read but not modified by the operator.
Machine control systems are able to communicate with the leak tester via the standard parallel (discrete I/O) interface or various other optional interfaces. 
A serial interface is available to connect the leak tester with a computer or printer. Other optional protocols are available (see technical data).


Pneumatic System

    • heavy-duty, robust diferential pressure transducer

• overload protection to 150 bar/g
• temperature compensated
• easy to maintain

  • microprocessor controlled electronic pressure regulator for filling and test pressure



Electrical System

  • modular design microprocessor system
  • battery buffered RAM for data protection
  • alphanumeric keypad
  • 5 inch color display
  • write-protect key switch to prevent unauthorized program changes
  • error message as plain text
  • menu guided programming and adjustment of parameters
  • various interface ports to communicate with control systems (see technical data)

Technical data


Program storage:   Battery buffered RAM
Measuring sensor:   Temperature compensated transducer for differential pressure, overload protection 150 bar/g
Display:   5 inch color liquid crystal display, 320x240 Pixel
Keyboard:   Alphanumeric
Measuring range:   ± 0 ... 6,000 Pa,
others on request
Resolution:   1 Pa, by means of high resolution
SigmaDelta A/D converter, 1 converter per channel
Measuring unit:   ml or l
Test programs:   up to 99
Filling and test pressure:   electronic pressure control with tolerance monitoring
0 ... 1 bar/g
(others on request)
Test parameters:   Upstream pressure ... bar
Compensation time 0.1 ... 999.9 s 
Feeding time 0.1 ... 999.9 sec 
Measuring time 0.1 ... 999.9 sec
Lower tolerance limit LT
Upper tolerance limit UT
No. of consecutive rejects
Write protection:   Key switch
Status indicator:  

Upper tolerance
Lower tolerance

Test data storage:   Up to 8,000 tests
(internal battery buffered RAM)
for larger data storage use front connection for external USB memory stick
optional: larger internal memory is available

1 parallel control I/O port

Control inputs:
24V DC; 500 mA 
1 Bit Automatic
1 Bit Device Ready
1 Bit Start 
8 Bit Program Select
1 Bit Abort

    Control outputs:
24 V DC; 500 mA 
short circuit proof
1 Bit Ready to operate
1 Bit Ready to test
1 Bit Error
1 Bit O.K.
1 Bit Lower tolerance 
1 Bit Upper tolerance
1 Bit Measuring

1x Serial Port RS 232 port or USB 2.0 for transfer of parameters, test results and counter readings.

1x USB 2.0 for transfer of parameters, test results and counter readings.

Optional Bus Interfaces:
FastEthernet, Profibus, Profinet, others on request

Housing:   19" rack mount case, 6 HU
Dimensions:   300x590x420 mm (HxWxD)
Power supply:   115 /230 V ± 10% 50 ... 60 Hz
Power consumption:   Approx. 100 VA
Air supply:   Test air: 1.5 bar > max. test pressure
Control air: max. 10 bar/g
filtered, dry and oil-free
Pneumatic ports:  

Air supply G 1/4"
Test medium port G1/4"
Test port G 1/8"
Reference port G 1/4"
Venting (through air silencer) G 1/4"

Weight:   Approx. 20 kg
Standard accessories:   Power cord, length approx. 2.5 m,
Spare key for write protection,
Operating manual
Order-No.:   Volume Tester 3925-0360
    Specifications and technical data are subject to change without notice



HeMaTech Prüftechnik GmbH & Co. KG
Siemensstr. 7
D-71409 Schwaikheim


Calibration Service for
Measurand Pressure




Tel.: +49 (0) 71 95-13 69 0
Fax: +49 (0) 71 95-13 69 29


Certified according to
ISO 9001:2015


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