UNIVERSAL RAI
®
, URAI-DSL, URAI-G and Metric Series
|
3
Safety Precautions
It is important that all personnel observe safety precautions to
minimize the chances of injury. Among many considerations,
the following should be particularly noted:
•
Blower casing and associated piping or accessories
may become hot enough to cause major skin burns on
contact.
•
Internal and external rotating parts of the blower and
driving equipment can produce serious physical injuries.
Do not reach into any opening in the blower while it is
operating, or while subject to accidental starting. Protect
external moving parts with adequate guards.
•
Disconnect power before doing any work, and avoid
bypassing or rendering inoperative any safety or protec-
tive devices.
•
If blower is operated with piping disconnected, place a
strong coarse screen over the inlet and avoid standing in
the discharge air stream.
CAUTION: Never cover the
blower inlet with your hand or other part of body.
•
Stay clear of the blast from pressure relief valves and the
suction area of vacuum relief valves.
•
Use proper care and good procedures in handling, lifting,
installing, operating and maintaining the equipment.
•
Casing pressure must not exceed 25 PSI (1725 mbar)
gauge. Do not pressurize vented cavities from an
external source, nor restrict the vents without first
consulting Roots.
•
Do not use air blowers on explosive or hazardous gases.
•
Other potential hazards to safety may also be associated
with operation of this equipment. All personnel working
in or passing through the area should be trained to
exercise adequate general safety precautions.
Operating Limitations
A ROOTS
™
blower or exhauster must be operated within
certain approved limiting conditions to enable continued
satisfactory performance. Warranty is contingent on such
operation.
Maximum limits for pressure, temperature and speed are
specified in TABLE 1 for various models & sizes of blowers &
exhausters. These limits apply to all units of normal construc-
tion, when operated under standard atmospheric conditions.
Be sure to arrange connections or taps for instruments,
thermometers and pressure or vacuum gauges at or near
the inlet and discharge connections of the unit. These, along
with a tachometer, will enable periodic checks of operating
conditions.
PRESSURE
– The pressure rise, between inlet and dis-
charge, must not exceed the figure listed for the specific unit
frame size concerned. Also, in any system where the unit inlet
is at a positive pressure above atmosphere a maximum case
rating of 25 PSI gauge (1725 mbar) should not be exceeded
without first consulting Roots. Never should the maximum
allowable differential pressure be exceeded.
On vacuum service, with the discharge to atmospheric
pressure, the inlet suction or vacuum must not be greater
than values listed for the specific frame size.
TEMPERATURE
– Blower & exhauster frame sizes are ap-
proved only for installations where the following temperature
limitations can be maintained in service:
•
Measured temperature rise must not exceed listed
values when the inlet is at ambient temperature. Ambient
is considered as the general temperature of the space
around the unit. This is not outdoor temperature unless
the unit is installed outdoors.
•
If inlet temperature is higher than ambient, the listed
allowable temperature rise values must be reduced by
2/3 of the difference between the actual measured inlet
temperature and the ambient temperature.
•
The average of the inlet and discharge temperature must
not exceed 250°F. (121°C).
•
The ambient temperature of the space the blower/motor
is installed in should not be higher than 120°F (48.8°C).
SPEED
– These blowers & exhausters may be operated
at speeds up to the maximum listed for the 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 a
limiting factor.
Special Note:
The listed maximum allowable temperature
rise for any particular blower & exhauster may occur well
before its maximum pressure or vacuum rating is reached.
This may occur at high altitude, low vacuum or at very low
speed. The units’ operating limit is always determined by the
maximum rating reached first. It can be any one of the three:
Pressure, Temperature or Speed.
