LYO-3 Lyophiliser — Chamber Entry and Shelf Stack Isolation
Shelf stack and condenser service inside a production freeze dryer. Covers hydraulic shelf collapse, clean steam sterilisation heat, silicone thermal fluid at temperature extremes, refrigerant, and vacuum that must be broken before the door.
How Setyr addresses Pharmaceuticals →
It refers to equipment that does not exist and illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain. It is not a document to adopt. Under (c)(4)(i) the employer must develop and document energy control procedures specific to their own machines, and under (c)(6) must inspect them at least annually.
12 points, in sequence
Chamber vacuum break to sterile filtered air.
Method: Break vacuum through the sterile filter and confirm the chamber is at atmospheric on two independent gauges before touching the door.
Caution: The door is held by several tonnes of force under vacuum. Forcing it, or releasing it suddenly, is the hazard.
Shelf stack hydraulic cylinder supply, which raises and holds the shelves for stoppering.
Method: Lower the stack fully onto its mechanical stops, THEN close and lock the hydraulic supply and bleed the accumulator.
Caution: A hydraulically held shelf stack collapses onto anyone inside the chamber if pressure is lost. Lower it before isolating, never after.
Mechanical shelf stack supports, inserted before entry.
Method: Insert the shelf supports at both ends and confirm seated. Must be ENGAGED.
Caution: The supports are the restraint once hydraulics are bled. Hydraulic isolation alone is not enough for chamber entry.
Lyophiliser main disconnect at the plant room panel.
Method: Open, lock, prove dead.
Caution: The shelf stack is hydraulically held. Removing electrical supply does not support the shelves.
Clean steam supply for chamber and condenser sterilisation.
Method: Close and lock the clean steam valve, then allow the chamber to cool and confirm surface temperature before entry.
Caution: A chamber that has just completed sterilisation is at 121 degrees C and stays hot long after the cycle ends.
Silicone thermal fluid circulation to the shelves, operating between minus 50 and plus 121 degrees C.
Method: Close and lock supply and return, then allow the shelf circuit to equalise to ambient and confirm at the shelf thermocouple.
Caution: The same fluid delivers a cryogenic burn at one end of the cycle and a thermal burn at the other. Isolated does not mean safe to touch.
Refrigeration compressor supply to the condenser coils.
Method: Open and lock the compressor disconnect.
Caution: The condenser holds refrigerant under pressure and its coils sit at minus 60 degrees C for hours after shutdown.
Nitrogen backfill supply used for stoppering.
Method: Close and lock the nitrogen supply, then bleed the backfill line.
Caution: An open nitrogen backfill into an occupied chamber is fatal within minutes and gives no warning.
Clean-in-place and WFI rinse supply to the chamber spray balls.
Method: Close and lock the CIP supply valve.
Caution: A CIP cycle starting with an entrant inside floods a sealed chamber with hot water.
Condenser defrost and ice melt drain.
Method: Open the melt drain and confirm the condenser is clear of ice before entry.
Caution: Ice on the condenser sublimes into the chamber and displaces the atmosphere the entrant is breathing.
Chamber door hydraulic clamp and its mechanical hold-open restraint.
Method: Set the door hold-open restraint and confirm engaged before entry. Must remain ENGAGED.
Caution: A door that closes on a hydraulic clamp with someone inside seals a pressure vessel around them.
Oxygen deficiency monitoring inside the chamber and at the door.
Method: Do NOT isolate. Confirm monitoring is in service and alarming audibly at the door.
Caution: Nitrogen backfill and subliming ice both displace oxygen. This is a permit-required confined space under 1910.146.
What your site must supply
This example is structurally complete and factually generic. The things below are the things only you can know — and they are exactly what makes a procedure yours.
- Your own asset and isolation-point tag numbers. The tags shown are illustrative and refer to equipment that does not exist.
- The actual location of every disconnect, valve and vent on your equipment.
- Measured stored-energy magnitudes and the dwell time required to dissipate them.
- Your verification method for each point, and who is authorised to perform it.
- Any additional energy sources present on your equipment and absent here.
Author this properly, once
Setyr holds procedures like this as living documents — bound to real isolation points, with lock registries, group lockout, person-in-charge custody and periodic review built in.