Calibrating leak detectors test leaks

Calibrating a leak detector is to be understood as matching the display at a leak detector unit, to which a test leak is attached, with the value shown on the label or calibration certificate. The prerequisite for this is correct adjustment of the ion paths in the spectrometer, also known as tuning. Cften the distinction is not made quite so carefully and both procedures together are referred to as calibration. 

In the calibration process proper the straight-line curve representing the numerically correct, linear correlation between the gas flow per unit of time and the leak rate is defined by two points the zero point (no display where no emissions are detected) and the value shown with the test leak (correct display for a known leak). 

In vacuum operations (spray technique, see Section 5.7.1) one must 

4 Leak detectors with quadrupole mass spectrometer (ECXDTEC II) 

INFICON builds leak detectors with quadrupole mass spectrometers to register masses greater than helium. Apart from special cases, these will be refrigerants. These devices thus serve to examine the tightness of refrigeration units, particularly those for refrigerators and air conditioning equipment. 

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Here the points suspected of leaking at the pressurized test specimen (see Fig. 5.4, d) are carefully traced with a test gas probe which is connected with the leak detector by way of a hose. Either helium or hydrogen can be detected with the INFICON helium leak detectors. The sensitivity of the method and the accuracy of locating leaky points will depend on the nature of the sniffer used and the response time for the leak detector to which it is connected. In addition, it will depend on the speed at which the probe is passed by the leak points and the distance between the tip of the probe and the surface of the test specimen. The many parameters which play a part here make it more difficult to determine the leak rates quantitatively. Using sniffer processes it is possible, virtually independent of the type of gas, to detect leak rates of about 10 mbar l/s. The limitation of sensitivity in the detection of helium is due primarily to the helium in the atmosphere (see Chapter 9, Table VIII). In regard to quantitative measurements, the leak detector and sniffer unit will have to be calibrated together. Here the distance from the specimen and the tracing speed will have to be included in calibration, too. 

The pumps generally have a capacity of 100 ml for a full pump stroke. The sample volume taken can be controlled by the number of pump strokes taken for each tube. Pumps must be properly maintained and procedures for leak testing and for measuring the volume and flow rate can be obtained from the manufacturers. The volume of the pump should be accurate to 5 % of the value stated. Detector tubes made by one manufacturer should not be used with a pump made by a different manufacturer since the pumps have different flow characteristics and could cause different lengths of stain. Each lot of detector tubes is calibrated by the manufacturer using his specific pump design. 

The 90 % NP steady state finally ended with a 13-day irradiation period which permitted irradiating the flux detectors to their saturation point, as well as completing the plant restart programme. On the one hand, the final requalification of the modifications made to the facility to improve protection against sodium fires was performed, with respect to which the good behaviour of that the new, so-called "sandwich", Na leak detection systems should be noted. On the other hand, two specific tests were also successfully performed first of all, with the reactor at power, calibrated... 

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