MTS Series 505G2 SilentFlo Hydraulic Power Unit Model 505G2-180 - Manual (Page 60)

The HPU starts out with one module running to create 30 gpm of available flow. This satisfies both the Startup
Flow requirement (10 gpm) and the Buffer Flow requirement (10 gpm). The demand rises and eventually hits
20 gpm.
At this point the on delay is started because the 20 gpm of actual flow and 10 gpm of Buffer Flow meet or
exceed the available 30 gpm. Because the flow stays above 20 gpm for the length of time Δton, another pump
module is started and available flow goes to 60 gpm.
Then a spike occurs which exceeds the available flow but because the duration of the spike is less than Δton,
another pump module is not started. Flow then continues to increase, but never exceeding the next trigger
point of 50 gpm for a duration of Δton.
Then flow drops off below 20 gpm. Because the flow does not stay below 20 gpm for the period of time Δtoff,
no pump modules are turned off.
Finally the flow tapers off and flow is below 20 gpm for the time Δtoff and the second pump module is turned
off.
ROD Example
Blue Line = Actual Flow Module flow = 30
Red Line = Available Flow Startup flow = 10 (Minimum flow capacity available)
t = Time Buffer flow = 4 (+6*) (Minimum flow capacity available beyond
demand - Startup flow must be satisfied first.)
*Actual buffer value is 6 gpm greater than entered value to
compensate for circ pump.
Startup flow + Buffer Flow = 20
Description Item
demand<20 1
50>demand>20 2
demand<20 3
50>demand>20 4
60 Series 505G2 SilentFlo™ Hydraulic Power Unit Product Information
Operation