Howden Roots Tri-RAM 409, Installation, Operation & Maintenance Manual

3

GEA19684  ISRB_2008 rev._11.15

Safety Precautions 

It is important that all personnel observe safety precautions 
to minimize the chances of injury. Among many consider-
ations, 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. Pro-
tect 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 associat-
ed with operation of this equipment. All personnel work-
ing 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, page 13 for various models & sizes 
of blowers & exhausters. These limits apply to all units 
of normal construction, when operated under standard 
atmospheric conditions. Be sure to arrange connections or 
taps for instruments such as thermometers and pressure or 
vacuum gauges at or near the inlet and discharge connec-
tions 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 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 ap-

proved only for installations where the following temperature 
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 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.

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15/02/2016   11:17:05