TM 5-3895-374-24-2
Temperature rise then is the limiting condition. In other words,
the operating limit is always determined by the maximum
rating reached first. It can be any one of the three: pressure,
temperature or speed.
Be sure to arrange connections or taps for thermometers
and mercury type pressure or vacuum gauges at or near the
inlet and discharge connections of the blowers. These, along
with a good tachometer. will enable periodic checks of
operating conditions to be made easily.
PRESSURE-On pressure service, the pressure rise in
pounds per square inch (kPa) (between blower inlet and
discharge) must not exceed the figure listed for the specific
blower frame size concerned. Also, in any system where the
blower inlet is at a positive pressure above atmosphere. the
discharge pressure must never exceed 25 PSI (172 kPa)
gauge regardless of blower size.
On
vacuum
service,
with
the
discharge
going
to
atmospheric pressure, the inlet suction or vacuum in inches of
mercury (Hg.) (kPa) must not be greater than the values listed
for the specific frame size.
TEMPERATURE-Various
blower
frame
sizes
are
approved only for installations where the following temperature
limitations can be maintained in service.
A.
Measured temperature rise in Fahrenheit degrees (Co)
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 reduced by 23
of the difference between the actual measured inlet
temperature and the ambient temperature.
C.
Average of inlet plus discharge temperature must not
exceed 220°F (104°C)
SPEED RANGE-UNIVERSAL RAI® blowers may be
operated at speeds up to the maximums listed for various
frame sizes. They may be direct coupled to suitable constant
speed drivers if pressure/temperature conditions are also
within limits. At low speeds, excessive temperature rise may
be the limiting factor as noted in the preceding example.
Table 1-Maximum Allowable Operating Conditions.
Inlet Vac.
Temp. Rise
Press. Rise
Frame
Speed
Inches Hg.
Fahr. Deg.
PSI
Size
RPM
(kPa)
(C)
(kPa)
22
5275
14 (47)
225 (125)
12 ( 82)
24
5275
14 (47)
185 (102)
7 ( 47)
32
3600
14 (47)
225 (125)
15 (101)
33
3600
14 (47)
170 ( 94)
12 ( 82)
36
3600
14 (47)
115 ( 64)
7 ( 47)
42
3600
14 (47)
240 (133)
15 (101)
45
3600
14 (47)
170 ( 94)
10 ( 68)
47
3600
14 (40)
130 ( 72)
7 ( 47)
53
2850
14 (47)
195 (108)
15 (101)
56
2850
14 (47)
180 (100)
10 ( 68)
59
2850
14 (40)
115 ( 64)
7 ( 47)
65
2350
16 (53)
250 (139)
15 (101)
68
2350
16(53)
240 (133)
12 ( 82)
615
2350
12(40)
130 ( 72)
6( 40)
76
2050
16 153)
250 (139)
15 (101)
711
2050
16 ( 53)
210 (117)
10 ( 68)
718
2050
12 ( 14)
130 ( 72)
6 ( 40)
BLOWER ORIENTATION
The unique removable feet feature of Roots UNIVERSAL
RAI" blowers permit field modification of blower mounting by
repositioning blower feet and gear box breather as shown in
Fig. 3.
Four blower mounting positions are possible:
1.
Horizontal mounting, vertical air flow, drive shaft on
left.
2.
Same as (1) except drive shaft on right.
3.
Vertical mounting, horizontal air flow, drive shaft on
bottom.
4.
Same as (3) except drive shaft on top.
To change blower mounting:
1.
Place blower on its feet.
2.
Loosen feet capscrews (32).
3.
Place blower on a solid base resting on the gear box
end with drive shaft on top.
4.
Remove feet. (Note-Feet capscrews (32) are longer
than cylinder capscrews (26), only capscrews (32)
are to be used for feet.)
5.
Remove cylinder capscrews (32) where feet are to be
re-installed. Install capscrews (26) in the location
previously occupied by feet capscrews (32).
6.
Install feet using capscrews (32).
7.
Place blower on its feet on flat surface.
8.
Loosen feet capscrews (32) and square up blower
and re-tighten capscrews (32).
9.
Gear box has four threaded holes, one with breather
and three with pipe plugs. Remove pipe plug (21)
from the top most hole. Remove breather (25) and
install it in the top most hole. Install pipe plug that
was removed from the top hole into the hole
previously occupied by the breather. The breather
and the pipe plug should be sealed with a thread
sealer.
For convenience. the position of the grease fitting
(37) and the relief fitting 138) could be interchanged,
however each bearing must have one grease fitting
137) and one relief fitting (38).
Figure 2-Breather Installation.
page 3-802
