Carrier 29D - Manual

Carrier
Operating and Maintenance
Instructions
29D
Automatic Water Strainer
Fig. 1 - Typical Automatic Water Strainer Installation
UNIT DESCRIPTION
The 29D Automatic Water Strainer cleans
foreign matter from the return water of a
Rotaspray® system. Figure 1 shows a typical
installation.
OPERATING CYCLE
Water enters the open end of the strainer drum
and passes outward thru the perforated skin. For­
eign matter is screened out of the water, and
covers the inside surface of the drum causing the
water level to rise on the dirty side of the tank.
The water level on the clean side rises until it
reaches the height of the high side electrode A
(Fig. 2). This sets the strainer into operation.
The drum begins to rotate and the drum flushing
sprays are turned on. The dirty portion of the
drum passes under the sprays, and foreign matter
is flushed from the drum into the sludge pan. The
pan flushing sprays wash the foreign matter from
the pan into a drain or a perforated collection
basket. (The water drains from this perforated
basket into a sump, and can be returned to the
dirty side of the tank by a small auxiliary pump.)
After the drum is cleaned of foreign matter, the
water levels equalize, and the strainer stops after
the timed operating cycle.
When the water falls below the low side elec­
trode B level (Fig. 2) the strainer starts to pro­
tect the pump suction when:
1. The "Rotaspray" units evaporate water, caus­
ing the water level on the clean side to drop
without a corresponding rise in water level on
the dirty side.
2. Changes in the system water flow requirements
suddenly drop the water level in the clean side
of the tank.
3. The high side electrode fails to operate.
I Carrier Corporation 1967 Printed in U.S.A. 12-67 29D-1SO