TECHNICAL INFORMATION
26
87-900-120-01 (A)
Safety actions
Backflow valve (factory setting: active)
Heater
OFF
This menu makes it possible to manage sensor
protection actions. Protecting the sensor means
restricting the flow of tracer gas (helium) to the amount
strictly necessary to trace leaks.
Backflow valve – Activation of the backflow valve is part
of the factory settings. This device is tripped when the
threshold set is exceeded and inverts the flow sampled
sampling the gas from the outlet port and then
discharging this through the probe normally used for
sampling.
Backflow functioning makes it possible to use the
helium-free gas present at the outlet port to clean the
entire pumping line and the helium exchange surface
inside the sensor. The device is useful in restricting the
flow of helium to the sensor. In addition to maintaining
correct operation of the sensor, this device also
restricts waiting times between one measurement and
the next (zeroing time).
Heater OFF – Heater Switching off is a further
protection in addition to the Backflow valve as it
temporarily reduces the permeability of the helium
exchange surface inside the sensor, restricting the flow
of helium to the sensitive element and therefore
guaranteeing correct operation in time.
MAINTENANCE
Sensor
Clean-up
.
Reading
adjustment
Sampling auto adjust
Battery
pack
PHD-4 Info
The Maintenance menu contains all the management
and self.-maintenance functions of the PHD-4.
Sensor
Clean-up
.
The “Clean-up” function makes it possible to eliminate
any residues of Helium inside the sensor and to obtain
fast, safe reset of the PHD-4.
Use the “Clean-up” function for faster zeroing after
measurement of a large quantity of Helium.
!
Do not start the “Clean-up” function in environments
with large quantities of helium.
Reading
adjustment
The “Reading adjustment” function makes it possible to
eliminate any imprecision in reading.
Start the procedure after correctly zeroing the device in
a helium-free environment.
When requested, provide the PHD-with a known mix of
Helium/Nitrogen (possibly calibrated and certified) and
correct readout using the “
∨
” and “
∧
” keys of the
specific screen page.
Follow the operating instructions provided by the HID
throughout the procedure.
In the absence of a calibrated mix, it is possible to use
the P/N Varian 969-3540 sample leak taking into
account that, in this case, reading precision is
approximate.
Sampling auto adjust
The Sampling autoadjust function offsets the
progressive loss of performance of the sampling line.
Execution of the function is requested by the user
interface every 20 h of operation but can also be
started “manually” at any time ( “Sampling auto adjust”
command).
It is also possible not to start the procedure when
requested (SKIP key) by the HID but this procedure is
initiated subsequently at each start-up until it is
executed.
NOTES
The “Sampling auto adjust” procedure makes an
indirect measurement of the flow sampled; therefore,
in some cases, it may take several minutes.
Battery Pack
The “Battery” menu is the menu used to access battery
pack management functions.
DANGER!
