PVI Industries QUICKDRAW PV500-26 - Manual (Page 11)

QUICKDRAW

Boiler Water Heater
11
PV500-26 06/12
7.5 Cleaning the Heat Exchanger (refer to figure on page 11)
1. Do not open until all pressure is removed, the unit is drained and the equipment surfaces cooled to ambient
temperature.
2. Heat exchangers subject to fouling or scaling should be cleaned periodically. A light sludge or scale coating on
the tube greatly reduces its effectiveness. A marked increase in pressure drop and/or reduction in performance
usually indicate cleaning is necessary.
3. Tube bundle removal:
a. When practical, leave tube bundle attached to collar assembly and remove by unbolting collar assembly
from tank.
b. During bundle removal, the dead weight of the bundle should never be supported on individual tubes or
contact any lined interior tank surface. Following removal, rest the bundle on the tube sheet, support plates,
or wood blocks cut to fit periphery of the bundle.
c. Tube bundles may be raised using slings formed by bending light sheet metal into a “U” form and attaching
lifting lugs to the ends of the sheets. Baffles can be easily bent and damaged if dragged over rough
surfaces.
d. Before reinserting the tube bundle into the unit place the ring/tank gasket over the end of the tube bundle
and bring forward to the backside of the tube sheet.
CAUTION: When cleaning a tube bundle, tubes should not be hammered on with any metallic tool and, in case it is
necessary to use scrapers, care should be exercised that the scraper is not sharp enough to cut the metal of the
tubes.