ferrous pillow block or extended housing.] Each wheel drive shall be
independent of any other wheel. Extended lubricant lines shall be provided
for maintenance access. Drive bearings shall be protected with water
slingers or shields.
2.3.4.2
Centrifugal Fans
[Forward curve] [Backward inclined] centrifugal scroll type fans shall be
provided with streamlined orifice inlet and V-belt drive, limited to three
wheels mounted on a corrosion protected drive shaft. Wheels and housing
shall be fabricated from aluminum or galvanized steel. Wheels shall be
dynamically balanced. Fan shaft first critical speed shall be not less
than 25 percent greater than operating speed. Fan shaft shall be mounted
in grease lubricated antifriction bearings with cast ferrous pillow block
housing. Extended lubricant lines shall be provided for maintenance access.
2.3.4.3
Fan Drives
V-belt drives shall be fitted with guards, [fixed pitch] [or] [adjustable
pitch] sheaves.
2.3.5
Fan Motors
Motor enclosures shall be [open drip-proof] [totally enclosed] type.
Motors and bearings shall be protected by location or with water slingers
or shields.
2.3.6
Refrigerant Circuit
Refrigerant containing components shall comply with ASHRAE 15, shall be
factory tested, cleaned, dehydrated, charged, and sealed. Each condenser
coil connection shall be fitted with a manual isolation valve of the ball
type and an access valve on the coil side. Receiver shall conform to ARI
495. [Receiver shall be insulated with not less than 25 mm 1 inch thick,
100 percent adhesive bonded, vaportight, flexible, closed-cell elastomer
and finished with two coats of solvent base PVC protective coating or 0.41
mm 0.016 inch thick aluminum jacket.]
2.3.7
Coils
Coils shall be constructed of copper or aluminum tubing with permanently
attached fins for thermally efficient contact. Casing shall be galvanized
steel or aluminum. [Coils for service in corrosive or salt laden
atmosphere shall be constructed of aluminum or with copper tubes and fins
and galvanized end sheets.] [In addition, coils shall be protected with
baked-on, minimum 0.076 mm 3 mil thick, phenolic coating.] [Separate
condenser circuit shall be provided for each compressor complete with
separate controls for each related fan.] [Unit shall provide not less than
[_____] degrees C degrees F subcooling.] Subcooling circuit shall be
liquid sealed. Condenser may be used for refrigerant storage in lieu of
separate receiver, provided that storage capacity is 20 percent in excess
of fully charged system. Where liquid flooding low ambient control is
furnished, a separate receiver shall be provided.
2.3.8
Low Ambient Condenser Controls
Unit shall be capable of operating in ambient temperature of [_____]
degrees C degrees F. Controls shall permit proper operation of system with
proper differential pressure across thermostatic expansion valve. Control
SECTION 15602N
Page 14
Previous Page
