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

GEA19684  ISRB_2008 rev._11.15

6

Motor on Inlet Side of Blower (Top Shaft)

Motor on Inlet Side of Blower (Bottom Shaft)

Motor on Drive Shaft

Side of Blower

Motor on Driven Shaft

Side of Blower

Motor on Discharge Side of Blower (Bottom Shaft)

Motor on Discharge Side of Blower (Top Shaft)

Top Shaft

INLET

DISCHARGE

Top Shaft

INLET

DISCHARGE

Bottom Shaft

INLET

DISCHARGE

INLE

T

DISCHAR

GE

Bottom Shaft

Drive Shaft

Driven Shaft

INLE

T

DISCHAR

GE

Drive Shaft

Driven Shaft

INLET

DISCHARGE

Fig. 1

 - Acceptable Blower Drive Arrangement Options

Above are suggested locations for available accessories.

Acceptable

Unacceptable

of 16 mesh backed with hardware cloth at or near the inlet 
connections. Make provisions to clean this screen of collected 
debris after a few hours of operation. It should be removed 
when its usefulness has ended, as the wire will eventually 
deteriorate and small pieces going into the unit may cause 
serious damage.

Pipe flanges or male threads must meet the unit connections 
accurately and squarely. DO NOT attempt to correct misalign-
ment by springing or cramping the pipe. In most cases this 
will distort the unit casing and cause impeller rubbing. In se-
vere cases it can prevent operation or result in a broken drive 
shaft. For similar reasons, piping should be supported near 
the unit to eliminate dead weight strains. Also, if pipe expan-
sion is likely to occur from temperature change, installation of 
flexible connectors or expansion joints is advisable. 

Figure 3, page 11 represents an installation with all accessory 
items that might be required under various operating condi-
tions. Inlet piping should be completely free of valves or other 
restrictions. When a shut-off valve can not be avoided, make 
sure a full size vacuum relief is installed nearest the unit inlet. 
This will protect against unit overload caused by accidental 
closing of the shut-off valve.

Need for an inlet silencer will depend on unit speed and pres-
sure, as well as sound-level requirements in the general 

surroundings. An inlet filter is recommended, especially in 
dusty or sandy locations. A discharge silencer is also normally 
suggested, even though Whispair units operate at generally 

lower noise levels than conventional rotary blowers. Specific 
recommendations on silencing can be obtained from your 
local Roots distributor.

Discharge piping requires a pressure relief valve, and should 
include a manual unloading valve to permit starting the unit 
under no-load conditions. Reliable pressure/vacuum gauges 
and good thermometers at both inlet and discharge are 
recommended to allow making the important checks on unit 
operating conditions. The back-pressure regulator shown in 
Figure 3, page 11 is useful mainly when volume demands 
vary while the unit operates at constant output. If demand is 
constant, but somewhat lower than the unit output, excess 
may be blown off through the manual unloading valve.

In multiple unit installations where two or more units 
operate with a common header, use of check valves is 
mandatory.

 These should be of a direct acting or free swing-

ing type, with one valve located in each line between the 
unit and header. Properly installed, they will protect against 
damage from reverse rotation caused by air and material 
back-flow through an idle unit.

After piping is completed, and before applying power, rotate 
the drive shaft by hand again. If it does not move with uniform 
freedom, look for uneven mounting, piping strain, excessive 
belt tension or coupling misalignment.

DO NOT operate the unit at this time unless it has been 
lubricated per instructions.

GEA19684_ISRB-2008_Tri-RAM_rev02.16.indd   6

15/02/2016   11:17:05