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Shellside fouling may be removed chemically (inhibitied acid) or mechanically (scraping,
wire brushing, light sandblasting, etc.).
Do Not Descale With Muriatic Acid (Hydrochloric Acid)
This can cause stress corrosion of stainless shell tubes in the XC heat exchanger. Use
an inhibited sulfamic acid boiler descalant (or similar product) in accordance with the
manufacturer's recommended procedures.
Proportional Control Valves
ƒ Replace worn or damaged rubber diaphragms (Undamaged diaphragms are essential
for proper operation of proportional control valves).
ƒ Reseat the valve as necessary by lapping with a coarse valve grinding compound and a
clockwise – counterclockwise rotary motion.
ƒ Replace worn or damaged flange gaskets.
Heat Exchangers
Make visual examination for suspected leaks in an assembled exchanger as follows:
1. Install a temporary ring flange in place of the head – so that tube ends are exposed
2. Pressurizing the shellside (max. 250 psig [17.3 bar] water or max. 50 psi [3.5 bar] air). If
pressurizing with air, use a bubble leak detector solution to detect leaks.
3. Repair minor leaks by one or more of the following actions:
a. Rerolling leaking tube-to-tubesheet joints.
b. Welding holes in tubes and U bends with stainless steel filler rod.
Extensive damage may require returning the exchanger to the factory for repair
Other Valves – V-Port Flow Control, etc.
Contact valve manufacturer for instructions regarding cleaning, reseating and repair parts.
 NOTE
Flow control valves are intentionally installed backwards . This arrangement provides greater
valve life and does not affect performance .
Sentry XC Boiler Blowdown System
13
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