37-1-614 Page 22
Altitude
(Feet above
See Level)
Maximum
Discharge
Pressure*
Maximum
Inlet
Vacuum*
1000
19.3 PSIG
16.4 Inches Hg.
2000
18.6 PSIG
15.8 Inches Hg.
3000
17.9 PSIG
15.3 Inches Hg.
4000
17.3 PSIG
14.7 Inches Hg.
5000
16.7 PSIG
14.2 Inches Hg.
*
Gauge readings are taken as close as possible to
blower openings. Above 5000 feet, consult
the nearest Gardner Denver Office.
FIGURE 3-5 – ALTITUDE – PRESSURE/VACUUM
ALTITUDE
– Maximum allowable discharge pressure and/or inlet vacuum will be decreased with
operation at altitudes. See FIGURE 3-5.
SPEED
– Refer to, page 19, for maximum and (Figure 3-6, page 23) for minimum speeds. Never operate
the blower below the minimum or above the maximum speed shown. There is a definite relationship
between blower speed, discharge pressure and/or inlet vacuum, and the resulting discharge air
temperature. Reduced speed at high pressure or vacuum can cause excessive heating which may result
in rapid blower failure. For engine-driven units provide an accurate speed indicator.
Examples of minimum allowable speed at given pressures or vacuums are listed in (FIGURE 3-6, page
23), as speed is reduced, pressure or vacuum must also be reduced.
EXAMPLE: Using a 7CDL11 blower, operating against 18 PSIG, minimum allowable speed is 1550 RPM.
NOTICE
Blower speed, line losses, elevation, and increased inlet temperatures will affect the maximum
operating limitations.
OPERATING TEMPERATURE
– Blower air discharge temperature will increase with higher operating
pressures or vacuums. Maximum allowable discharge is 355°F. If the discharge temperature continues
to exceed 355°F., stop the blower at once and correct the trouble.
Do not continue to run a blower that is overheating. Check the blower for damage before
restarting.
Lubricating oil temperature will increase with increasing discharge air temperature. Oil temperature in the
discharge end sump will exceed that in the inlet end sump. Oil sump temperatures at the discharge end
in the 200 – 275° F. range are not uncommon.
STOPPING BLOWER
– Where possible, reduce the system pressure to zero gauge before stopping the
blower. To prevent backflow of foreign material into the blower on shutdown, provide a check valve in the
discharge line.
On engine-driven units, idle the engine for a few minutes prior to shutdown.
