Honeywell VRX180 user manual 40 F0 Sterilization Prompts

Programming Function Blocks and Features

Sterilization

The output CVn OV is a “kill time”, F0, which quantifies the destruction of microorganisms during a sterilization process. F0 represents the number of minutes after which the microorganism population is decreased by one decimal or log unit. The F0 formula is:

F0 = ∑ [dt x (10(T-Tref)/Z)] where:

dt = time between F0 measurements, in minutes. Dt is equal to the scan cycle of the instrument in minutes.

T = measured temperature input, in °C

Tref = reference temperature (121°C typical) Z = product-dependent temperature constant

This function also compares the calculated F0 value to the desired F0 value, Fd (Preset). When F0 equals or exceeds Fd, the function activates its discrete output CVn OS; this output remains ON(1) until the F0 calculation is reset via the Reset Input.

The output CVn A2 is the Time Remaining (Tr) at the current temperature to achieve Fd and is calculated as follows:

(Fd – F0)

Tr = _________

10(T-Tref)/Z

The F0 calculation will be reset and the F0 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 F0 Sterilization Prompts

Prompt		Range/Selections	Definition
OUT LOW LIMIT		OFF or number	Displayed output value will be clamped and will flash
			when these limits are exceeded.
OUT HIGH LIMIT
RESET		OFF, discrete parameter, 0,	Reset input
	1
TEMP INPUT		OFF, analog parameter,	Measured temperature in degrees C
		number
REFERENCE TEMP		OFF, analog parameter,	Reference temperature
		number
TEMP CONSTANT		OFF, analog parameter,	Temperature constant Z
		number
DESIRED F0		OFF, analog parameter,	Desired F0 (Fd)
		number

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