SCP SCIENCE
56
KeyPad
Version 1.0
TYPICAL HEATING RATES FOR
Digi
PREP HT
1st Step
When programming the fi rst 'time to temperature'
and the 'time at temperature' cycle, it is assumed that
the
Digi
PREP HT
will begin the cycle from ambient
temperature. To enter the 'Time to Temperature' for
the fi rst step is a simple matter of using the graph
below.
Example:
Heat
a
Digi
PREP HT
block from 25
o
C (ambient)
to 300
o
C.
Solution:
From the graph, draw a line from 300
o
C across
to the curve representing the voltage that the
Digi
PREP HT
is connected to. (208 V is typical
in North America, 230 V in typical Europe). Draw
a line down from this point to the Time Scale.
Time to Temperature = at least 25 minutes.
2nd Step
When programming the additional ramp and
soak cycles, the Time to Temperature will depend
on the last temperature reached – i.e. the previous
setpoint. This becomes more complex, as the
heating rates for the
Digi
PREP HT
depend on
both the Setpoint temperature and the
Δ
T. Two
equations are needed:
Equation 1:
Δ
T = T
fi nal
– T
initial
Equation 2: Time to Temperature =
Δ
T / rate
HT Typical Heating Rates (
°
C/min) vs
Setpoint temperature and
Δ
T
Δ
T (
°
C)
Setpoint Temperature
25-50
50-225
225-350
350 +
0-25
1
3
2
2
25-200
-
20 min
4
3
200-325
-
-
8
4
325-425
-
-
-
5
HT - Typical Time to Temperature
0
50
100
150
200
250
300
350
400
450
500
0
20
40
60
80
100
Time to Temperature (minutes)
S
et
poi
nt
Te
m
p
er
at
ur
e (
d
eg
C
)
208 Volts
230 Volts
HT- Typical Time to Temperature
Setpoint T
emperature (°C)
Time to Temperature (minutes)
208 Volts
230 Volts
Содержание DigiPREP
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