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

ISRB

 2005 GEA 20260

Page 16 of 24

2500 Series DVJ Blowers 

Information in this section not to conflict with other 

sections of this manual. 

Operating Limitations 

Normal DVJ applications have a vacuum on the inlet 

and atmospheric pressure on the discharge jet port 

connections. 
Any unnecessary restrictions of discharge flow or 

atmospheric air inlet to the jet port reduces the 

cooling air flow and limits blower operation, as the 

maximum temperature rise will occur below the 

normal limits of vacuum level. 

NOTE: 

One jet port must have a full size inlet 

silencer with no valve or other restrictions. The other 

port must have the metal cover plate installed. 

Installation 

A temporary cover is installed on one jet port and a 

permanent cover on the other at the factory. A 

silencer must be installed in place of the temporary 

cover before operating the blower, however, the 

permanent cover and silencer locations may be 

exchanged if the installation requires. 
The permanent cover must be removed, both jet 

plenums inspected and cleared of foreign material, 

then the permanent cover and silencer installed in the 

desired locations before operating. Full size jet and 

discharge silencers are desirable, however, the jet 

silencer may be reduced one nominal size providing 

either the vacuum level is less than 18.5” Hg or the 

gear speed is below 3650 feet per minute. Both the 

jet silencer and the discharge silencer may be 

reduced one nominal size in applications with 

vacuum levels less than 18.5” Hg and a gear speed 

below 3650 feet per minute. 
Jet and discharge flow restrictions result in increased 

blower temperature rise and should be checked as a 

possible cause if the temperature rise limits blower 

operation to less than the maximum vacuum level. 

Backpressure limits are shown in Table 5 of this 

section. No valves should be used in the discharge 

piping or jet silencer piping. 
Some type of protection, such as a filter or screen 

(1/4”mesh) is necessary to stop foreign particle entry 

through the jet port. Outside installations may also 

require some weather protection to prevent the entry 

of rain or snow. An elbow or some other pipe 

configuration is desirable to assist in keeping the 

screen clear of foreign particles and the direct entry 

of rain or snow. 

Operation 

All check points should be followed with the addition 

and/or superseded by the following: 
(1, add.) Be careful no rags, bolts, or dirt have been 

left in the cylinder slot inlet plenums 
(2, add.) No valves should be installed in the 

discharge pipe or jet silencer pipe 
The blower is suitable for vacuum operation only. A 

water manometer should be used on the discharge 

plenum to determine that the maximum discharge 

pressure has not been exceeded. 

Troubleshooting 

All troubleshooting points in this manual should be 

followed with the addition/or supersedure of the 

following: 
Excessive temperature rise - check for possible 

cylinder slot inlet flow restriction, excessive 

backpressure on the discharge, and troubleshooting 

checklist in the appropriate instruction and operation 

manual. 

NOTES: 

No valves should be installed in the discharge or jet 

silencer pipe. 
Jet silencer should be a chamber type (non-packed). 
 
 
 
 
 
 
 
 
 

ISRB 2005 GEA 20260.indd   16

17/09/2015   12:53