York R123 - Manual (Page 149)

FORM 160.55-O1 (604)
149
YORK INTERNATIONAL
LD00475
FIG. 65 – DIAGRAM, MEGGING MOTOR WIND INGS
GENERAL
Maintenance of condenser and cooler shells is im-
por tant to provide trouble free op er a tion of the chiller.
The wa ter side of the tubes in the shell must be kept
clean and free from scale. Proper main te nance such as
tube clean ing, and testing for leaks, is covered on the
fol low ing pages.
CHEMICAL WATER TREAT MENT
Since the mineral content of the water circulated through
coolers and condensers varies with almost ev ery source
of supply, it is possible that the water being used may
cor rode the tubes or deposit heat resistant scale in them.
Reliable water treatment companies are avail able in most
larger cities to supply a water treating process which will
great ly reduce the corrosive and scale form ing prop er ties
of almost any type of water.
As a pre ven tive measure against scale and corrosion
and to pro long the life of cooler and con dens er tubes, a
chemical analysis of the water should be made pref er a bly
before the system is installed. A reliable water treat ment
com pa ny can be consulted to determine whether water
treat ment is nec es sary, and if so, to furnish the proper
treat ment for the particular water condition.
CLEANING COOLER AND CON DENS ER TUBES
Cooler
It is difÞ cult to de ter mine by any par tic u lar test wheth er
pos si ble lack of per for mance of the water cool er is due
to fouled tubes alone or due to a com bi na tion of trou bles.
Trouble which may be due to fouled tubes is indicated
when, over a period of time, the cool ing ca pac i ty de-
creas es and the split (tem per a ture dif fer ence between
water leav ing the cool er and the re frig er ant tem per a ture
in the cooler) in creas es. A grad u al drop-off in cool ing
ca pac i ty can also be caused by a gradual leak of re frig -
er ant from the sys tem or by a com bi na tion of foul ed
tubes and shortage of re frig er ant charge. An ex ces sive
quan ti ty of oil in the cooler can also contribute to erratic
per for mance.
Condenser
In a condenser, trou ble due to fouled tubes is usu al ly
indicated by a steady rise in head pres sure, over a pe ri od
of time, ac com pa nied by a steady rise in con dens ing
tem per a ture, and noisy operation. These symp toms may
also be due to foul gas buildup. Purging will re move the
foul gas re veal ing the effect of fouling.
TUBE FOULING
Fouling of the tubes can be due to deposits of two types
as follows:
1. Rust or sludge, which Þ nds its way into the tubes
and ac cu mu lates there. This ma te ri al usu al ly does
not build up on the inner tube sur fac es as scale, but
does interfere with heat trans fer. Rust or sludge can
gen er al ly be re moved from the tubes by a thorough
brush ing process.
2. Scale, due to mineral de pos its. These de pos its, even
though very thin and scarce ly de tect able upon phys-
i cal in spec tion, are high ly re sis tant to heat transfer.
They can be removed most ef fec tive ly by cir cu lat ing
an acid so lu tion through the tubes.
CONDENSERS AND COOLERS
8