Schwing SP 500 - Page 140

140
Appendix
SP 500 / 750-15 / 750-18 / 1000 / 1250 Operation Manual
yards3/hr and 627 PSI has been plotted for visual rep-
resentation, but you can see immediately that the PF
of the job (62,700) is bigger than the PF of the unit
(56,650). The curved black line represents the PF of
the unit. If the unit is going to be able to handle the job,
the intersection of pressure and yd3/hr will be to the
right and down from the curved line. Anything to the left
or above the line is beyond the power of the hydraulic
pumps. If we could order this same unit with the pumps
set to a higher Kw, the PF of the higher Kw unit would
be 72,600, which would be su󰀩cient.
Plotting the intersection of our hypothetical job again,
you can see that it falls within the power zone of the
hydraulic pumps of the higher KW unit.
Bearing in mind that the nomograph should only be
considered accurate to within ±10 percent, you should
always calculate conservatively, and allow for the graph
tolerance. In the case of our example, we should still be
safe even if the pressure required were 10% greater
(690 PSI).What if you already own the pump shown in
our example? Is there anything that can be done to the
job specications to make the unit with the less power-
ful pumps work? You could use the smaller PF unit or if
you can get permission to do any of the following things:
• Pump the top of the building at 85 yd3/hr instead
of 100 yd3/hr.
• Pump the top of the building at a 6-inch slump in-
stead of 5-inch. (This would still be within speci-
cations.)
• Remove some of the rubber hose at the end of the
horizontal run. Normally, with job circumstances
that did not require a substantial vertical run, you
could also use 6-inch instead of 5-inch-diame-
ter pipeline. But in our example, the entire
vertical run was made with the boom. The boom
can never support 6-inch pipeline.
P (in PSI)
Q (in yd
3
/hr)
Power Factor number (PF)
Working power (in kW
)
For vertical placing,
add 1.105 PSI per foot
of level difference.
72,600
132 kW
English to Metric Conversion factor is PF ÷ 18.966
3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600 400 200
200
180
160
140
120
100
80
60
40
20
Example Job
up lft 132Kw Qwad 2000R-eps