Honeywell VRX180 Manuale Utente
Programming Function Blocks and Features
Video Recorder – User Manual
132
Sterilization
The output CVn OV is a “kill time”, F
0
, which quantifies the destruction of microorganisms during a
sterilization process. F
0
represents the number of minutes after which the microorganism population is
decreased by one decimal or log unit. The F
0
formula is:
F
0
=
∑ [dt x (10
(T-Tref)/Z
)]
where:
dt = time between F
0
measurements, in minutes. Dt is equal to the scan cycle of the instrument in
minutes.
T = measured temperature input, in °C
T
ref
= reference temperature (121°C typical)
Z = product-dependent temperature constant
This function also compares the calculated F
0
value to the desired F
0
value, F
d
(Preset). When F
0
equals or exceeds F
d
, the function activates its discrete output CVn OS; this output remains ON(1) until
the F
0
calculation is reset via the Reset Input.
The output CVn A2 is the Time Remaining (Tr) at the current temperature to achieve F
d
and is
calculated as follows:
(F
d
– F
0
)
Tr =
_________
10
(T-Tref)/Z
The F
0
calculation will be reset and the F
0
value will remain at zero while the Reset Input is ON(1). The
calculation will resume when the Reset Input goes OFF(0) again.
Table 4-40 describes the Sterilization prompts. See Table 4-2 for additional prompts.
Table 4-40 F
0
Sterilization Prompts
Prompt
Range/Selections
Definition
OUT LOW LIMIT
OUT HIGH LIMIT
OFF or number
Displayed output value will be clamped and will flash
when these limits are exceeded.
when these limits are exceeded.
RESET
OFF, discrete parameter, 0,
1
1
Reset input
TEMP INPUT
OFF, analog parameter,
number
number
Measured temperature in degrees C
REFERENCE TEMP
OFF, analog parameter,
number
number
Reference temperature
TEMP CONSTANT
OFF, analog parameter,
number
number
Temperature constant Z
DESIRED F0
OFF, analog parameter,
number
number
Desired F
0
(F
d
)