Howden Roots 2500 Series WHISPAIR MAX, Installation, Operation And Maintenance Manual

ISRB

 2005 GEA 20260

Page 3 of 24

Safety Precaution 

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 protective 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, 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 fi rst consulting Howden 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 2, page 9 for Whispair Max and 

Table 3, page 9 in the 2500 Series DVJ Section, for 

allowable speeds for various models & sizes of 

blowers and 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 connections of the unit. 

These, along with a tachometer, will enable periodic 

checks of operating 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 rating of 25 psi 

gauge (1725 mbar) should not be exceeded without 

first consulting Howden 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 

approved 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). 

ISRB 2005 GEA 20260.indd   3

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