Constant Flow Delivery System
Ann Suter, Wildland Fire Chemical Systems - MTDC
Constant Flow Tank
1000 gallons released at 225 gallons per second
550
Constant flow systems have door controls that allow the
delivery system to behave as a single tank. Once the
drop controller establishes the flow rate, the coverage
level produced remains constant over the duration of
the drop. The effect of changing the volume released
will only change the length of the drop, not the flow
rate.
500
450
Flow Rate
gallons per second
400
350
300
250
The graph to the left shows the flow rate over time of a
constant flow tank. The more horizontal this line is the
more constant the flow rate is and the more even the
coverage will be.
200
150
100
50
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Seconds
The system achieves constant flow by increasing the
door opening as the liquid level falls inside the tank.
For drops that require low flow rates, the doors will
open a little and gradually widen as the fluid evacuates.
For drops that require high flow rates, the doors open
wide and have little room for adjustment. The result is
the flow rate is not as constant.
Revision Date 2/1/03
asuter@fs.fed.us 406-329-4815