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Manual 111-082010_Nall Mass Flowmeters Page 22 of 23
a) What is the sensitivity of the totalizer?
b) What is the total flow indicated by the 13,500 count?
c) What is the average flow rate over the 7 hour period?
Solution: a) The full scale flow rate for the TNALL-P/HS-10S is 10 SCCM. The full-scale count rate for the
totalizer is 100 counts per minute.
Sensitivity = F. S. flow rate
F. S. countrate
= 10 std. cm³/min.
100 counts/min.
d) The total flow indicated by 13,500 counts is:
Total flow = total counts X sensitivity
= 13,500 counts X 0.1 std cm³/min.
= 1350 std cm³
c) The average flow rate over the 7 hour period is the total flow divided by the time:
Average Flow Rate = Total Flow
Time
= 1350 std cm³
7 hrs X 60 min/hr
= 1350 std cm³
420 min.
= 3.2 std cm³/min.
If a special gas is used with the flowmeter (other than that for which it was originally calibrated), refer to
Section 5.5 to determine the new full-scale flow rate for the special gas. Once the full-scale rate for the
special gas is obtained, it may be used with the equations above to determine the sensitivity of the totalizer in
std. cm³/count.
11.2.4 Maintenance
The totalizer is all solid-state and is designed for a long life expectancy and no maintenance is normally
required. Should the totalizer or counter need repair, return them to Teledyne Hastings with a statement
describing the problem; use the form on page 35.
11.3 Chassis Model (NALL-C):
Hastings Chassis Linear Mass Flowmeters are designed for installations where the electronic circuits are
remotely mounted from both the transducer and readout. It is particularly useful in applications where the
meter must be located long distances from the transducer. Thus, the transducer cable is kept short, and the
meter may be located long distances from the Chassis without concern for cable losses. Also, panel space is
reduced to that of the meter only. The Chassis is designated by adding the suffix “C” to the Cabinet Model
number; NALL becomes NALL-C.
11.4 Current Converter (NAll-P/CC):
A 4-20 mA current converter is an option available with the Hastings Mass Flowmeter. The Hastings 4-20
mA may be built into a flowmeter package or supplied as a separate unit. The converter produces a 4-20 mA
current signal from the 0-5 VDC output of the flowmeter.