Fluke 6270A - TEST Port; REF Port

6270A
Operators Manual
20
TEST Port
Pressure instruments and devices to be tested are connected to the TEST port.
Tubing connected from the Test port to the load volume should have an internal
diameter >3 millimeter (1/8 inch). Tubing should be <5 meters (15 feet) when
minimum diameter tubing is used.
To prevent oils, grease, solvents, and water that could be present in a Unit Under
Test (UUT) from contaminating the Product, a Contamination Prevention System
(CPS) is available for use with the Product. The CPS sits on a bench inside a test
stand that provides a platform to test pressure instruments and devices. The
CPS connects directly to the TEST port. For more information, see
Contamination Prevention Accessory (CPS).
Note
Excessive leaks in the test volume affect control stability and
possibly cause measurement errors in the UUT.
Caution
To prevent damage to the Product, when the Product is
connected to a system with liquid contaminants, take proper
precautions to purge the system and test line. Not doing so can
cause Product contamination and result in a need for non-
warranty service.
Note
Minimize the length of the test connection tubing to enhance control
performance and reduce pressure setting time.
The Product pressure control will not operate properly if there are
excessive leaks in the test system. The maximum acceptable leak
rate for optimal automated pressure control operation and to ensure
in tolerance measurements with default pressure control parameters
is
± 0.5 % of set pressure/minute. In DYNAMIC CONTROL mode, to
handle higher test system leak rates, use CUSTOM CONTROL to
increase the hold limit.
REF Port
The REF port (Reference port) is open to atmosphere for gauge measurements
or it can be connected to the reference port of the pressure instruments and
devices to be tested.
Instruments with a low full-scale pressure range require special handling to
assure their performance. These instruments are sensitive to atmospheric
pressure changes, including disturbances in the atmospheric pressure. The
reference side must be carefully controlled or changes due to wind, air handlers,
doors shutting, and more will cause major variations. The Product tracks these
changes but it may not track in the same way as the pressure device under test.
To control these changes, Fluke Calibration recommends that the reference port
(also referred to as the "test-(test minus)" or "low" port of all relevant devices be
tied to the REF port of the Product.