A50-186tf, Gravity Flow Method, A50-187tf

GRAVITY FLOW METHOD (Fig. 34) — Do not add solu- tion faster than the vent can exhaust the generated gases.

When condenser is full, allow the solution to remain over- night then drain the condenser and flush with clean water. Fol- low acid manufacturer’s instructions.

FORCED CIRCULATION METHOD (Fig. 35) — Fully open the vent pipe when filling the condenser. The vent may be closed when the condenser is full and the pump is operating.

Regulate the flow to the condenser with a supply line valve. If the pump is the non-overloading type, the valve may be fully closed while the pump is running.

For average scale deposit, allow the solution to remain in the condenser overnight. For heavy scale deposit, allow a full 24 hours. Drain the condenser and flush with clean water. Follow acid manufacturer’s instructions.

a50-186tf

Fig. 34 — Gravity Flow Method

a50-187tf

Fig. 35 — Forced Circulation Method

Fan Motor Lubrication — The fan motor was properly lubricated at the time of manufacture. Lubricate the fan motor(s) with SAE-20 non-detergent electric oil.

IMPORTANT: PILLOW BLOCK STYLE FAN BEAR-

INGS: Bearings have been prelubricated with high quality grease. Bearings must be relubricated once every 6 months or every 2500 hours of operation whichever comes first.

Fan Bearing Lubrication — Inspect the fan bearings for proper lubrication every 6 month or 2500 hours of opera- tion, whichever comes first. Standard units have grease fittings on the fan shaft bearings, located on each side of the blower wheel. Lubricate bearings with a lithium-based grease (NLGI Grade 2).

Fan Sheaves — Factory-supplied drives are pre-aligned and tensioned, however, it is recommended that the belt tension and alignment be checked before starting the unit. Always check the drive alignment after adjusting belt tension.

To install sheaves on the fan or motor shaft:

1.Isolate power to the unit.

2.Remove side unit access panel(s).

3.Remove any rust-preventive coating on the fan shaft.

4.Make sure the shaft is clean and free of burrs. Add grease or lubricant to bore of sheave before installing.

5.Mount sheave on the shaft; to prevent bearing damage, do not use excessive force.

Each factory-assembled fan, shaft, and drive sheave assem- bly is precision aligned and balanced. If excessive unit vibration occurs after field replacement of sheaves, the unit should be rebalanced. To change the drive ratio, follow the steps in the Evaporator Fan Performance Adjustment section (page 51).

After 1 to 3 minutes of operation, check the belt tension. Also check tension frequently during the first 24 hours of oper- ation and adjust if necessary. Periodically check belt tension throughout the run-in period, which is normally the initial 72 hours of operation.

ALIGNMENT — Make sure that fan shafts and motor shafts are parallel and level. The most common causes of misalign- ment are nonparallel shafts and improperly located sheaves. Where shafts are not parallel, belts on one side are drawn tight- er and pull more than their share of the load. As a result, these belts wear out faster, requiring the entire set to be replaced be- fore it has given maximum service. If misalignment is in the sheave, belts enter and leave the grooves at an angle, causing excessive belt and sheave wear.

Shaft Alignment — Check shaft alignment by measuring the distance between the shafts at 3 or more locations. If the dis- tances are equal, then the shafts are parallel.

Sheave Alignment

1.To check the location of the fixed sheaves on the shafts, use a straightedge or a piece of string. If the sheaves are properly aligned, the string will touch them at the points indicated by the arrows in Fig. 36. Rotate each sheave a half revolution to determine whether the sheave is wob- bly or the drive shaft is bent. Correct any misalignment.

2.With sheaves aligned, tighten cap screws evenly and progressively.

NOTE: There should be a 1/8-in. to 1/4-in. gap between the mating part hub and the bushing flange. If the gap is closed, the bushing is probably the wrong size.

3.With taper-lock bushed hubs, be sure the bushing bolts are tightened evenly to prevent side-to-side pulley wob- ble. Check by rotating sheaves and rechecking sheave alignment. When substituting field-supplied sheaves for factory-supplied sheaves, only the motor sheave should be changed.