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For your nearest Roots office contact information, please consult the last page of this document.
Safety Precautions
It is important that all personnel observe safety precautions
to minimize the chances of injury. Among many considera-
tions, the following should be particularly noted:
•
Blower casing and associated piping or accessories may
become hot enough to cause major skin burns on con-
tact.
•
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 inlet and discharge openings.
•
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, lift-
ing, installing, operating and maintaining the equipment.
•
Casing pressure must not exceed 25 PSI (1725 mbar)
gauge. Do not pressurize vented cavities from an exter-
nal 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 exer-
cise 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 1a, page14 in the GAS Section, TABLE 1b,
page 15 in the DVJ Section, TABLE 1c, page 19 in the DPJ
Section and TABLE 1d, page 20 in the VJ Section for allow-
able speeds for various models & sizes of blowers and
exhausters. These limits apply to all units of normal con-
struction, when operated under standard atmospheric condi-
tions. Be sure to arrange connections or taps for instruments
such as 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 oper-
ating conditions.
PRESSURE
– The pressure rise, between inlet and discharge,
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 rat-
ing 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 pres-
sure, the inlet suction or vacuum must not be greater than
values listed for the specific frame size.
TEMPERATURE
– Blower & exhauster frame sizes are
approved only for installations where the following tempera-
ture limitations can be maintained in service:
•
Measured temperature rise must not exceed listed val-
ues 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 driv-
ers 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 maxi-
mum rating reached first. It can be any one of the three:
Pressure, Temperature or Speed.
