User's Manual

5 Using the manifold
13
Display
Mode
Function
Automatic mode
If the automatic mode is
activated, the testo 557
digital manifold automatically
changes the display of the
high and low pressure. This
automatic change occurs
when the pressure on the
low-pressure side is 1 bar (15
psi) higher than the pressure
on the high-pressure side.
During the change,
Load (2
s) is shown in the display.
This mode is especially
suited to air conditioning
systems which cool and heat
(heat pumps).
Pos: 34 /TD/Prod ukt verwenden/te sto 557/M essung durchfü hren testo 5571 @ 17\mod_1 426501166387_ 79.docx @ 2118 56 @ 255555 @ 1
5.2. Performing the measurement
WARNING
Risk of injury caused by refrigerant that is at high pressure,
hot, cold, or poisonous!
> Wear safety goggles and protective gloves..
> Before pressurizing the measuring instrument: Always fasten
the measuring instrument at the hanging hook in order to
prevent it from falling (risk of breakage)
> Check if the refrigerant hoses are intact and connected
correctly before each measurement. Do not use a tool to
connect the hoses. Only tighten the hoses by hand (max.
torque 5.0 Nm/3.7 ft*lb).
> Do not exceed the permissible measuring range (0 to 870 psi /
0 to 60 bar). Pay particular attention with systems with
refrigerant R744, as these are often operated with higher
pressures.
Measuring
1. Connect and apply pressure to the manifold.
2. See readings.
Note: With refrigerants that have a temperature glide,
“Zeotropes” the evaporation temperature Ev/to and