Howden ELF - Preventive Maintenance

Howden 24-07.030r04 18/25
E-series Axial Flow Cooling Fans
Service Manual
h. Measure the power. In case the fan power
(after correction for temperature) is different
than required, adjust the pitch angle
accordingly (3 degrees tolerance from de-
sign blade angle). Note: the absorbed
power is inversely proportional to the air
temperature. If a larger adjustment is re-
quired, after temperature correction, verify
with a new fan selection or contact
Howden.
i. Re-tighten the U-bolts after 50-75 hours in
operation, or 120-150 hours stand still.
Check the tightening torque of the bolts of
the tapered bushing and the coupling
flange bolts.
V. PREVENTIVE MAINTENANCE
Though the impeller requires little
maintenance, it is recommended to conduct
inspections at regular intervals, to check
damage due to vibrations, fouling or wear
and tear.
Actual recommended maintenance intervals
will depend on the use and operation of the
complete system and shall be determined by
the operator.
Check for smooth operation of the fan
and listen for irregular noise or vibrations.
De-energise the fan and make a visual
inspection for deposits, and or damages.
Visually inspect the blades surface and
blade stems for cracks. Hairline cracks
could appear in resin rich areas around
the edges of the fan blade and will nor-
mally stop progressing. Hairline cracks in
itself are harmless, however we advise
you to fill these cracks with a touch-up
material (PU filler, e.g. Sikaflex 252) to
prevent moisture penetration affecting
the blades. Howden Cooling Fans can
provide you a repair kit complete with in-
structions.
For all other cracks we suggest to send
photographs to Howden Cooling Fans for
evaluation.
Important
De-energise the fan and use lock out and
tag out procedures prior to performing
adjustments, service, inspections or
lubrication.
WARNING
Contact with rotating fan blades can cause
severe injury or death. Never insert items
into the fan to determine movement or
direction of rotation. Install fan guards or
screens on arrangements with exposed
fans. Always use lockout and tag out
procedures before performing fan
adjustments, maintenance, service or
inspection.
Important
Following measures must be emphatically
respected for potentially explosive
environments and to comply with Directive
94/9/EC (ATEX 100):
Electrically earthed metal bearing
support to avoid sparkling by electrical
static discharge
Minimum prescribed tip clearance to
avoid rubbing along the impeller casing.
Directions for design of the impeller
support structure according to Howden
document 03-07.341