TESTO 557, Instruction Manual

Page: 17 / 28

6 Using the product
17
Measuring
✓
The actions described in the chapter “Preparing for
measurement” have been performed.
1. Apply pressure to the measuring instrument.
2. Read the measuring values.
With zeotropic refrigerants, the evaporation temperature
to/Ev is displayed after the complete evaporation / the
condensation temperature tc/Co is displayed after complete
condensation.
The measured temperature must be assigned to the
superheating or subcooling side (t
oh
<--> t
cu
). Dependent on
this assignment, the display will show t
oh
/T1 resp. ∆ t
oh
/SH
or t
cu
/T2 resp. ∆ t
cu
/SC, depending on the selected display.
- Reading and display illumination are flashing.
• 14,5 psi/1 bar before the critical pressure of the refrigerant is
reached,
• when the max. permissible pressure of 870 psi/60 bar is
exceeded.
Key functions
> [ ▲ ] or [ ▼ ] : Change the readings display.
Possible display combinations:
Evaporation pressure
Refrigerant evaporation
temperature
to/Ev
Condensation pressure
Refrigerant condensation
temperature
tc/Co
or (only with inserted temperature sensor)
Evaporation pressure
Measured temperature t
oh
/T1
Condensation pressure
Measured temperature t
cu
/T2
or (only with inserted temperature sensor)
Evaporation pressure
Superheating ∆ t
oh
/SH
Condensation pressure
Subcooling ∆ t
cu
/SC
With two inserted NTC sensors ∆ t is additionally displayed.
> [Mean/Min/Max] : Hold readings, min. / max. readings, show
mean values (since switching on).
Leak test / pressure drop test
The temperature compensated leak test can be used to
check the leak tightness of systems. For this purpose both
the system pressure and the ambient temperature are