TESTO 557, Instruction Manual

Page: 12 / 28

5 First steps
12
Representation Explanation
AUTO OFF Automatic switch-off time, instrument
switches off after 30 minutes if no
temperature probe is connected and there is
no pressure apart from ambient pressure.
T
fac
Temperature compensation factor, icon is
shown on the display if the function is
disabled.
Operating the valve actuators
With respect to the refrigerant flow path the digital manifold
behaves just like a conventional four-way manifold. The passages
are opened by opening the valves. The applied pressure is
measured with the valves closed and the valves opened.
>
Open the valve: Turn valve actuator anticlockwise.
> Close the valve: Turn valve actuator clockwise.
WARNING
Valve positioner tightened too tightly.
• Damage to the PTFE seal (1).
• Mechanical deformation of the valve piston (2) leading to the
PTFE seal (1) falling out.
• Damage to the thread of the threaded spindle (3) and the valve
screw (4).
• Broken valve knob (5).
Tighten the valve positioner only hand-tight. Do not use any tools
to tighten the valve positioner.