T
HERMO
F
ISHER
S
CIENTIFIC
S
S
S
S
S
ECTION
ECTION
ECTION
ECTION
ECTION
1
1
1
1
1
I
NTRODUCTION
O
PERATING
G
UIDE
, TEOM 1405
1-9
The mass flow controllers (MFCs) in the TEOM 1405 Monitor are
internally calibrated for a standard temperature and pressure of 25° C and 1
Atmosphere (1013.2 millibars or 760 mm Hg). For
passive
flow control, the
user must enter the seasonal average temperature (Ave. Temp.) and
average barometric pressure (Ave. Pres.) at the measurement site to allow
the instrument to sample at the correct volumetric flow rate (Section 4).
The microprocessor calculates the correct mass flow set point
(Flow_Rate
STP
) with this information using the following formula:
Mass Flow
Mass Flow
Mass Flow
Mass Flow
Mass Flow
Controllers
Controllers
Controllers
Controllers
Controllers
where:
FlowSP
PASSIVE
= Control set point to mass flow controller (equivalent
flow at 25° C and 1 Atmosphere)
FlowSP
Vol
= Volumetric flow rate set point (l/min)
Temp
AVG
= Average temperature entered by the user (°C)
Temp
STD
= Standard temperature (25°C)
P
AVG
= Seasonal average barometric pressure entered by the
user (Atmospheres, where 1 Atmosphere = 1013.2
millibars or 760 mm Hg)
P
STD
= Standard pressure (1 Atm)
Alternately, Active flow control can be set up to automatically measure the
ambient temperature and pressure using the hardware supplied.
Note.
Note.
Note.
Note.
Note. When using actual conditions for active volumetric flow control,
substitute the actual (local) temperature and pressure as measured by the
instrument for the average temperature and pressure variables in
equation above.
▲
15
.
273
Temp
15
.
273
Temp
P
FlowSP
FlowSP
AVG
STD
AVG
Vol
Passive
+
+
×
×
=
STD
P
Содержание TEOM 1405
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