RS COMPACT FREEZE TUNNEL, Руководство по эксплуатации и обслуживанию

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OPERATION & MAINTENANCE MANUAL
CompactFreezer
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Exhaust Blower Interlock
Injection of liquid nitrogen can only occur if the exhaust blower motor is in operation. In addition, the
Compact Freezer is equipped with an optional exhaust interlock that is tied into the emergency stop loop.
i.e., if the exhaust blower is not operating, the freezer will shut down (the belt, liquid nitrogen and
circulating fans will stop). Before troubleshooting, the freezer should be locked out at the main
disconnect switch if maintenance on the exhaust blower is required. It is also good practice to install a
disconnect switch at the blower on the roof.
Emergency Stop Buttons
There is an Emergency Stop (e
‐ stop) button; it is located on the control panel above the freezer. In event
of an emergency (e.g. major product jam or unexpected stoppage), during normal operating mode or in
cleaning mode, operators can shut down the freezer within seconds. The solenoid valves that control
liquid nitrogen injection will fail closed to prevent further liquid nitrogen injection, and the conveyor
belt and circulating fans will stop. The exhaust will continue to run after the e
‐ stop is activated, to ensure
the proper removal of nitrogen vapor. To re-start freezer turn the fan, conveyor, and instrument power
buttons to the off position. Once all three are OFF, then turn each back to the on position.
Freezer Door Interlock
Limit switches monitor the open/close status of the freezer doors. The safety
‐ rated limit switches are
wired normally open to prevent the circulating fans and cryogen from activating when the doors are open.
When the doors close, the limit switch contacts also close, energizing the circulating fans and the
cryogenic solenoid valves. If the doors are opened during operation, the circulating fans ( 3 m o d u l e
f r e e z e r s o n l y ) and liquid nitrogen injection will stop.
Pressure Relief Valves
A pressure relief valve is located on the freezer between the manual shutoff valve at the freezer, and the
two solenoid valves. The relief valve prevents the possibility of pipe rupture due to the trapped liquid
expanding to gas. Relief valves should be piped away to an outside location, to ensure proper removal
of nitrogen gas if a valve failure should occur.
Dynamic Bracking (3 module freezer)
Electric Dynamic Bracking is used to almost instantly stop the 1/2HP 1200 rpm convection fan motors
motors whenever any upper door is raised, the safety limit switch will shut all circulating fan motors off,
as well as cryogen injection in the freezer.