considered, together with the required head and desired throughput (GPM
or BPH), to establish maximum efficiency in design. The maximum head
capacity of a pump station is the total head against which it will pump
to provide maximum pipeline capacity. Maximum head capacities are only
for use in emergency operations and are never used in normal operations.
Pump stations should not be operated at maximum capacity except for
emergencies. Operation under emergency conditions should not exceed 24
consecutive hours.
PART C - PARALLEL AND SERIES INSTALLATION OF PUMPS
Electrical storage batteries are described in terms of series or parallel
hook-up. In order to get 12 volts of electricity, two 6-volt batteries
may be connected in series. The two 6-volt batteries connected in
parallel provide 6-volts of electricity, but the current is doubled. A
hydraulic system is very similar to an electrical system because the head
capacity resembles voltage and the flow rate resembles the current.
Two pumps connected in series double the head capacity of a single
pump while the flow rate in GPM or brake horse power (BHP) remains the
same as for one pump. Two pumps connected in parallel double the flow
rate, while the head capacity remains the same as for one pump.
Parallel operation is not normally used on petroleum pipelines. Pump stations are costly to operate and
require man power. The objective in pipeline design is to use as few pump stations as possible. The size of
the pipeline maintains the required volume. Pump stations are designed to push fuel products as far as
possible down the line. As a result, pump stations are connected in series.
PART D - PUMP GRAPHS
Observe how the pump graph is constructed (Figure 11-1). The graph
consists of a coordinate system. It is a uniform scale which means there
is an equal space between all units on the graph in both directions.
Rate of flow is plotted along the X or horizontal axis increasing from
left to right in GPM on the bottom and BPH on top. The remaining
variables are plotted along the Y or vertical axis. The RPM curve
defines what is referred to as the operating speed of the pump.
12-99
QM 5099
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