Milnor 6458, Installation Manual

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MSSM0102BE/2003123V (1 of 3)
È ABOUT THE STEAM AND HOT OIL CONTROL SYSTEMS
FOR MILNOR DRYERS
MILNOR steam dryers are available with an optional Y-type ON/OFF steam valve. MILNOR hot oil dryers use
a modulating oil inlet/bypass valve.
Ê How To Protect Steam Coils From Water Hammer Damage
Steam coils can be damaged when steam pressure is suddenly applied to a water (condensate) filled coil, or
when the steam is “wet” with a high water content. The damage occurs because the condensate is forced through the
coils with great speed causing a water hammer condition which can be likened to many jack hammers inside the
coil. The result will be damaged coils, especially at the ends where the water must turn quickly.
Steam coils that have been damaged by water hammer are not warrantied. Any steam coil
making a popping sound or cracking sound is in grave danger of serious water hammer
damage.
1. Maintain the bypass piping (machines with optional ON/OFF valve, FIGURE 1) in good working order, to prevent
cracking and popping sounds when steam is turned on. Do not operate Dryer unless bypass piping is in good
working order.
2. If a steam trap must be replaced, be sure the pressure rating of the replacement trap is suitable for the steam
pressure in your plant and that the replacement trap’s capacity is equivalent to the original equipment.
DRYERS WITH STEAM TRAPS RATED 85-180 PSI (6-12 ATU) WILL NOT OPERATE PROPERLY
BELOW 60 PSI (4 ATU). STEAM TRAPS RATED 160-225 PSI (11-15 ATU) WILL NOT OPERATE
PROPERLY BELOW 115 PSI (8 ATU). These pressure ranges refer only to the range of pres-
sures through which the trap may be reasonably expected to operate properly. They are not
necessarily an indication of the safe operating pressure for the steam coil. Always refer to the
nameplate for the specific dryer to determine the maximum permissible pressures.
Ê About the Standard Steam Control System
1. Each Dryer has a strainer and steam trap (FIGURE 1), to handle steam that condenses in the coil as it heats
the passing air which dries the goods.
Clean and “blow down” steam trap and strainer screens
after 40 hours of operation and periodically thereafter.
Clogged strainer screens will cause longer drying times.
Ê About the Optional On-Off Steam Control System
with Y-type, Air Operated Valve
In addition to the steam trap and strainer, dryers equipped with the optional Main Steam Inlet ON/OFF valve
are fitted with:
a. A steam inlet valve which is open whenever the Dryer is drying (whenever the Cooldown Bypass Damper
is closed). This normally closed (air-to-open) valve shuts off the flow of steam to the Dryer during Cool-
down, if the Dryer Master Switch is OFF, and whenever the Dryer is not being used.
b. Bypass piping to keep coils warm and condensate minimized while the Main Steam Inlet valve is OFF,
but machine is in standby, with steam provided to the machine.
Î FIGURE 1
(MSSM0102BE)
Î Standard Steam Piping
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