Dresser Roots DVJ WHISPAIR, Установка, эксплуатация и обслуживание

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4 | Dresser Roots
Operating Limitations
To establish and maintain continued satisfactory performance,
and Roots blower must be operated within certain approved
limiting conditions. The Manufacturer’s warranty is, of course,
contingent on such operation.
Any unnecessary restrictions of discharge flow or atmospheric
air inlet to the cylinder slots reduces the cooling air flow and
limits blower operation as the maximum temperature rise
will occur below the normal limits of vacuum level. For an
open loop system, the discharge pressure must not exceed
0.2" H
2
O per 100 FPM gear speed. Example - 10" GD
unit running at 1500 rpm, maximum discharge pressure =
0.262*10*1500*0.2/100=7.9" H
2
O. This also applies to close
loop system, this is the pressure difference between the blower
discharge and the casing bleed back port. The pressure drop
through the jet filter/silencer must not exceed 10" H
2
O. The
the listed maximum allowable temperature rise (increase in air
temperature between inlet and discharge) for any particular
blower may occur well before maximum speed or maximum
pressure rating is reached.
Temperature rise then is the
limiting condition. In other words, the operating limit is
always to be determined by the maximum rating reached first.
It can be any one of the three: pressure/vacuum, temperature
or speed.
Be sure to arrange connections or taps for thermometers and
pressure or vacuum gauges at or near the inlet and discharge
connections of the blower. These, along with a good tachom-
eter, will enable periodic checks of operating conditions.
Note - Some special purpose blowers may be assembled
with nonstandard clearances other than shown in Table 8 or 9.
These units may be operated at vacuum and or temperature
rises higher than those listed in applicable Table 1. Before
doing so however, request specific approval from the nearest
Sales Office. Normally, when a blower is operated at the
design condition stamped on its nameplate, the specified limits
apply.
VACUUM - With the discharge going to atmospheric pressure,
the inlet suction or vacuum in inches of mercury (kPa) must not
be greater than the values listed for the specific frame size. The
pressure rise in pounds per square inch (kPa) between blower
inlet and discharge, must not exceed the figure listed for the
specific blower and frame size concerned. The blower case
is rated for a maximum pressure of
25 PSI (172 kPa) gauge
regardless of blower size.
TEMPERATURE
- Various blower frame sizes are approved
only for installations where the following temperature limitations
can be maintained in service.
A. Maximum temperature rise (T.R.) in Fahrenheit degrees
(°C) must not exceed listed values when the inlet is at
ambient temperature. Ambient is considered as the
general temperature of the space around the blower.
This is not outdoor temperature unless the blower is
installed outdoors.
B. If inlet temperature is higher than ambient, the listed
allowable temperature rise values must be calculated
using blower selection program (Contact Sales Office if
you do not have access to the program).
SPEED RANGE - Blowers may be operated at speeds up to
the maximums listed for the various frame sizes. They may be
direct coupled to suitable constant speed drivers if vacuum/
temperature conditions are also within limits. Splash lubricated
blowers should not be operated below 1000 FPM gear speed
for proper lubrication.
Frame Size
Inlet Vacuum Temperature Rise Speed
Inches HG mm HG. °F °C RPM Maximum
1016 27.0 684 275 153 1800
1021 27.0 684 300 167 1800
1220 27.0 684 275 153 1500
1222 24.0 610 275 153 1500
1428 22.5 571 300 167 1300
1431* 22.0 558 300 167 1300
1639 18.5 470 300 167 1130
1643 16.5 420 300 167 1130
1833 24.0 610 300 167 1000
1838 21.5 546 300 167 1000
Table 1 - Maximum Allowable Operating Conditions - DVJ
*Requires GE drive arrangement above 20" Hg.