OPERATION & MAINTENANCE INSTRUCTIONS
For CASE-SQ / RD / RT and OIFRP Series Induced Draft Counterflow Cooling Tower

PRE START UP:
Before a CASE Tower is started up for the first time, or after a long shut down, it should be cleaned and inspected. When a new installation is involved with supervision of a CASE field supervisor, the following steps have already been carried out as part of the cooling tower installation. The erection instructions provided with the field assembly cooling towers also include these following instructions. Therefore, under these circumstances, the Pre Start procedure instructions need only be followed again, if the cooling tower should be shut down at a later stage.

DANGER - TURN OFF, TAG AND LOCK FAN MOTOR SWITCHES

• Inspect the cooling tower to see that perforated holes in the branch pipes, fill media and cold water basin are free of debris of foreign matter.
• If any foreign matter is present, wash it into cold water basin with the use of a high-pressure water spray gun. Drain the water away through the drain connection in the cold water basin and manually remove any debris left in the cold water basin - particularly from the suction screen.
• Check the fan for free rotation and proper tip clearance in the fan cylinder. Inspect to see that all blades are true to prevent unbalanced operation.
• Check to see that the float valve is operating properly and fill the cold water basin with water right up to the bottom of the overflow pipe in the cold water basin. Primes the circulating water pumps (prime it manually, if necessary, and allow it to run until the connected piping system is full of water.

It may be necessary to use a supplementary supply of water to that supplied by the float valve at this stage, if the connected piping system requires a lot of water to fill it.
The water, which fills the piping system, must come from the cold water basin and if the quantity required is great, then the level of water in the cold water basin could drop to a point where the pump cavitates.
The addition of supplementary water to assist the float valve at this stage, and under these circumstances, will prevent pump cavitation.
When the whole water circulating system has been operating satisfactorily for ten minutes, shut off the pump.
The level of water in the cold water-basin will rise and some water may run to waste via the overflow pipe.
This is to be expected, particularly if supplementary water has been added.
During this ten-minute period, the pump should be watched to see that it is operating correctly without unusual noise or vibration.

STARTING UP:

• Start the fan and observe to see that it is rotating in the direction indicated by the direction arrow attached to the fan cylinder. Observe that the fan is operating smoothly without undue vibration. If it does vibrate excessively, stop the fan as soon as possible and check for out of balance due to misaligned blades, or loose bolts in the bearing housing.
• Start the circulating pump and let the circulating system settle down. Then with an ammeter, check that fan when operating, is not causing the motor to draw more than nameplate amps. If more than nameplate amps is being drawn, re-pitch fan.
• Dump the water in the cold water basin via the drain twice within the first day of operation to ensure that the system is clean.
• Cold-water collecting basin is at normal operating water level in the basin at bottom of the cooling tower. Adjust the float valve arm to achieve this. In any case, enough depth must be maintained to prevent pump from pulling air into suction line.
• Water make-up and blow down. The amount of "make-up" water that is required to maintain adequate water depth in the cold water collecting basin depends upon the "evaporation loss", "drift loss" and 'blow down".
• Water for the make-up averages between 0.1% to 1% of the cooling tower circulated water depending on cooling range and above mentioned governing factors.
• Make sure that the make-up float is operating properly and doesn't leak when closed.
• See that cold water outlet suction screen is properly installed and that cavitation is not occurring (swirls of water in the vicinity of the outlet indicates the possibility of cavitation).
  

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