Heat exchangers
DESCRIPTION OF TECHNICAL CHALLENGE
Increasing numbers of heat exchangers are used in a modern car design. Strict new
governmental emissions and fuel-economy requirements drive the need for major HVAC andpowertrain improvements. This, in turn, will increase the need for stricter leak testing, but also
require additional high-quality heat-exchange systems. The introduction of exhaust gas
recirculation adds an additional EGR cooler to each vehicle using this technology. Increased
use of turbo chargers to increase gas mileage leads to increased production numbers ofcharge air intercoolers. For mobile air conditioners, the industry is currently switching from
R134a (used as refrigerant in car air conditioners for the last decade) to the moreenvironmentally-friendly (lower GWP), but flammable HFO-1234yf. The flammability, inparticular, drives the need to test all MAC components (in this case, the evaporator and thecondenser) for lower leak rates. Also, more complex designs (introduced to efficiently use thelimited underhood space) restrict the use of traditional testing methods (like water bath testing).

THE INFICON SOLUTIONIntegral Testing During Production
Depending on the size of the heat exchanger and the required throughput, two tracer gas
solutions are available today that are not affected by temperature changes:
Accumulation method

Vacuum leak testing

Leak rate requirements

Water-tight, oil-tightRefrigerant-tightThroughput

Low to medium

Medium to highPart size

Small to medium

Medium to large

For small to medium parts that need to be tested for water/oil leaks with low to
medium throughput, leak detection with helium or hydrogen in an
accumulating chamber under normal pressure (accumulation method)
provides an economical solution for leak testing heat exchangers.
In a simple chamber, the test part is pressurized with helium or hydrogenthrough its test gas connection so that the test gas can escape through any
leaks into the accumulating chamber. Fans then ensure an even distribution of
the test gas in the chamber – so, independent of the position of the leak,
precise measurement values are guaranteed. The T-Guard Helium sensor
then determines the test gas content in this atmosphere and calculates theleak rate of the part from this value.LEAK TESTING OF COMPONENTSHEAT EXCHANGERS

For larger parts that need to be tested with medium tohigh throughput, or parts that need to be tested forrefrigerant leaks, leak testing with helium in a vacuum
chamber is recommended. For this testing process,the heat exchanger is sealed before large vacuum
pumps pull a vacuum once the chamber lid is closed.
The part and chamber are evacuated simultaneously;
subsequently the part is backfilled with helium.
Helium then has the opportunity to migrate outwards
and if a leak is present, the INFICON LDS3000 HeliumLeak Detector (which is valved into the vacuum pumps
after the part has been filled with helium) detects thehelium atoms as they emerge from the heat exchanger.

Leak location in rework
After one or more leaks have been detected, the leak needs to be located andrepaired. Depending on the leak rate requirements, the heat exchanger is either
filled with forming gas (a 5% hydrogen in 95% nitrogen mixture) or helium. The
sniffer tip of the Sensistor Sentrac Hydrogen Leak Detector or the Protec
P3000(XL) Helium Sniffer Leak Detector is then moved along the welds of theheat exchanger and a leak is detected, if the sniffer tip comes in contact with thetracer gas escaping from a leak in the heat exchanger. After the leak has been
repaired, the repair can be verified with this same method.

BENEFITS OF HELIUM / HYDROGEN LEAK TESTING•

Accurate and repeatable measurements for reliable results of leak testing•Test method independent of temperature and moisture•

Cost efficient leak testing•High sensitivity

LEAK TESTING OF COMPONENTSHEAT EXCHANGERS

EXAMPLES OF HEAT EXCHANGERS IN A CAR DESIGNAutomotive
Component

Evaporator

Typical leak rates

10 – 10 mbarl/s

10 – 10 mbarl/s 10 – 10 mbarl/s

Recommended
INFICON products

T-Guard
LDS3000
Modul1000

T-Guard
LDS3000
Modul1000

Modul1000
LDS3000
T-GuardSensistor ISH2000

Automotive
Component

Charge-Airintercooler

EGR cooler

Evaporator for EV
battery cooling

Typical leak rates~ 10 mbarl/s~ 10 mbarl/s

10 – 10 mbarl/s

Recommended
INFICON products

T-Guard
LDS3000

T-Guard
LDS3000

T-Guard
LDS3000-4-5-3Condensor-4-5-3

Oil cooler-2-4

Water cooler-4-2~ 10 mbarl/s
Sensistor Sentrac
T-Guard(LDS3000)-5* Click on the product name to get more product information from our website

For more information, please visit us atwww.inficonautomotive.com

w w w . i nf i c o n. c o m

re a c hus @ i nf i co n. c o m

Due to our continuing program of product improvements, specifications are subject to change without notice.
miae00en-a (1507)©2015 INFICON