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Technical Note:
A Practical Guide to Flow Measurement
where additional data collection equipment is
unavailable and when many data points are to be
recorded.
2.
measures 7-3/4" x 5-1/4" x 7-1/4". It has a life of
about 10 hours.
Power Sources
Only power sources for the Turner Designs Model 10
Series Fluorometers will be discussed. Injectors,
pumps, recorders, and other accessories should be
chosen with consideration of the type of power
available and the manufacturer’s recommendations.
The Model 10 will operate on either AC or DC current.
For AC operation, any source that will provide 50-400
Hz and 105-130 volts at 0.3 amperes is satisfactory.
Conversion to 210-260 volts, at 0.25 amperes
requires only a simple power cord change. The
instrument is completely internally protected against
voltage surges. No additional precautions need be
taken, although prolonged operation above 130 volts
(or 250 volts) is not advisable.
For DC operation, any portable generator or battery
that will provide 11-16 volts at 3 amperes may be
used. The negative lead should be grounded.
We assume that batteries are more commonly used
for portable application. The prime requirement of the
battery is that it must deliver 3 amperes for the period
of expected operation without the voltage dropping
below 11. Most batteries are capable of this.
Any battery will produce fewer total ampere hours at
high current drain than at low drain. The loss is
dramatic if the drain exceeds the purpose for which
the battery was designed. For example, size "D"
alkaline flashlight batteries produce 1.5 volts and
some have a capacity of ten ampere hours. A bank of
eight would produce 12 volts, and might be assumed
to yield two amperes for five hours. In fact, a twoampere drain would cause the voltage to drop below
11 in only a few minutes. However, in a pinch,
paralleling four banks of eight, or even better, nine,
should provide many hours of operation.
A 12-volt lead-acid battery is probably the best choice
for most applications. One example is a battery
designed for snowmobiles, with special caps to
prevent any battery acid loss. The Gould SN-9L is
rated at 32 amperes, weighs 21 pounds, and
One disadvantage of this battery and all automotivetype batteries is that they are not designed for
complete discharge without damage. Several dozen
complete charge-discharge cycles is all that can be
expected, unless they are recharged immediately
after each discharge.
A battery designed especially for field work,
permitting complete discharge without immediate
recharge is the Globe GC-1220B 20-ampere hour
battery. The electrolyte is gelled to prevent spilling. It
weighs 16 pounds, and measures 7" x 6-1/2" x 5". It
has a life of about 6 hours.
Lead-acid batteries of under 20-ampere hour capacity
should not be used, because they will not supply a
steady 3 ampere drain. Nickel-cadmium batteries
have the same limitations.
3.
Dye Injectors
There are three basic types of constant-rate injectors:
constant displacement pumps, constant-head
(gravity-feed) devices, and regulated pressure
systems.
Constant displacement pumps are frequently used.
One series of commercially available pumps which
appear to be nearly ideal for field work is the RP-BG
series manufactured by Fluid Metering, Inc., and
available through Turner Designs. All units feature
continuously variable flow rate -- from full forward to
full reverse. Models with maximum flow rates of 6.7,
16, 20.2 and 48 ml/minute against back pressures up
to 75, 30, 15 and 5 PSIG respectively are available.
Current drain is between 0.06 and 0.1 amperes from
a 12-volt battery. They are self-priming, and
warranted to deliver constant flow to 1% from full flow
down to 10% of full flow.
The pump that we recommend as the hardiest is the
Model RP-BG 75-2CSY (Turner Designs catalog #10008). A laboratory test yielded constant flow to better
than 1% over a battery voltage range of 10-15 volts,
against a zero pressure head. One of our sales
engineers has carried one of these pumps for five
years. He keeps it at the same adjustment (full flow).
www.turnerdesigns.com
998-5000
Revision A 05/31/2001
Page 21 of 29