A helium leak detector permits the localization of leaks and the
quantitative determination of the leak rate, i.e. the gas flow
through the leak. Such a leak detector is therefore a helium flow
meter. In practice the leak detector performs this task by
firstly evacuating the part which is to be tested, so that gas from
the outside may enter through an existing leak due to the pressure
difference present. If only helium is brought in front of the leak
(for example by
using a spray gun) this helium flows through the leak and is pumped
out by the leak detector. The helium partial pressure present in the
leak detector is measured by a sector mass spectrometer and is
displayed as a leak rate. This is usually given in terms of volume
flow of the helium (pV-flow).
Important Specifications
The two most important features of a leak detector are its
measurement range (detection limits) and its response time.
The measurement range is limited by the lowest and the highest
detectable leak rate. The lowest detectable leak rate is defined by
the sum of drift and noise in the most sensitive measurement range.
Usually the sum of noise amplitude and zero drift per minute is made
to be equivalent to the lowest detectable leak rate. With leak
detectors the amount of drift is so
low, that the noise amplitude alone determines the detection limit.
The highest detectable leak rate depends strongly on the method
employed. Especially the counterflow method and partial flow
operation (see description below) permit the measurement of very
high leak rates even with a sensitive helium leak detector. In
addition the multistage switchable high impedance input amplifiers
of the leak detectors also permit the measurement of high leak
rates.
In practical applications, especially in the localization of leaks
the response time is of great significance. This is the time it
takes from spraying the test object with helium until a measured
value is displayed by the leak detector. The response time of
the electronic signal conditioning circuitry is an important factor
in the overall response time. In the case of leak detectors the
response time of the electronic circuitry is well below 1 s.
The volume flow rate for helium at the point of the test object is
of decisive significance to leak detection on components which are
pumped down solely by the leak detector. This volume flow rate
provided by the leak detector takes care of the helium entering
through a leak and it
ensures quick detection by the leak detector. On the other hand the
volume of the test object delays the arrival of the helium signal.
The response time can be calculated on the basis of the following
simple equation:
Response time for helium tA = 3
(for 95% of the final value)
with V = Volume of the test object
SHe = Volume flow rate for helium at the point of the test object
(or at the inlet of the leak detector, if it alone pumps down the
test object).
Helium Leak Detector
PhoeniXL 300
The PhoeniXL 300 is a portable multipurpose helium leak detector and
equally well suited to both service and series production testing.
Its rugged design and its ease of use make the PhoeniXL 300 to a
userfriendly leak detector in its class.
Advantages to the User
Lowest detectable leak rate
Short He recovering time condition
Quick start-up
Extremely fast response time
Oil-free gas admission system
One of the smallest helium leak detectors in the world
High sensitivity
Fast leak rate readout also at low leak rates
Typical Applications
Leak tests in connection with
Quality assurance
Automotive industry
Analytical instruments
Systems manufacture
Power station engineering
Research and development
Semiconductor industry
High vacuum and ultra-high vacuum engineering
Ideal tool for industrial series production testing – in
the cooling and air conditioning industries, for example
In connection with the sniffer lines which are available
as accessories the PhoeniXL 300 may also be used as a
sniffer leak detector. In connection with a partial
flow pump set the PhoeniXL 300 may also be used for the
detection of leaks on large vessels.
For a PDF file of this product please contact us here.
file.
