Log: Cleanroom Differential Pressure and Door Interlock Monitoring

This is a ready-to-use routine log for the pressure cascade between adjacent classified rooms and the interlock logic on airlock doors that protect it. It keeps the cascade in its qualified state between requalifications by recording the readings, the direction, the alarms, and the interlock checks an inspector expects to see controlled every shift. Replace every <<FILL: ...>> placeholder, set your validated differentials, and route it through your batch record or facility monitoring system. A filled specimen follows. This is educational reference content, not regulatory advice.

Purpose

Qualification establishes the pressure cascade and its direction; this log demonstrates it held, shift after shift, and that the airlock interlocks that protect the cascade actually worked. A sustained low, reversed, or unrecorded differential, or a defeated interlock, is exactly the kind of gap an inspector probes for because it quietly undermines every other control in the room.

Validated differentials and interlock logic (set once, from qualification)

Field definitions

Log

Exception handling

1. Any “No” answer in Direction correct, Within range, or Both doors open together triggers an immediate notification to <<FILL: role>> and an entry in the deviation system per <<FILL: deviation management SOP-ID>>.
2. Hold use of the affected room or airlock until the exception is assessed; do not resume routine use on the assumption the reading will self-correct.
3. For a reversed or sustained low differential, assess product impact for the period in question before any product made or handled during that window is released.

Retention

Retain this log per the records retention schedule, for not less than <<FILL: retention period>>, with the underlying continuous electronic trend data (where the facility monitoring system records it) retained and linked rather than summarized away.

Filled specimen

The following shows one shift’s entries for an example Grade B/C boundary, so you can see the level of detail expected. The company, rooms, and numbers are illustrative; replace them with your own.

The night shift entry shows the expected response: the low-differential alarm fired, was logged with its clear time, and generated a deviation reference rather than being noted as a passing reading with an asterisk. The investigation (outside this log) traced the dip to a door held open during a material transfer and confirmed no product was in the room during the 5-minute excursion.

Common inspection findings this log prevents

• Differential readings recorded as a single pass/fail with no actual numeric value, so a slow drift toward the alarm setpoint is invisible.
• An alarm event noted verbally but never logged or linked to a deviation.
• Interlock function assumed rather than verified on a defined schedule.
• Both airlock doors observed open at once with no entry and no investigation, collapsing the cascade for that period with no record it happened.
• The pressure cascade reviewed gauge by gauge with nobody checking that the room-to-room scheme still makes directional sense as a whole.

How to adapt this log

1. Set your validated differentials, alarm setpoints, and interlock logic from your own qualification data, not from this template’s illustrative numbers.
2. Set the check frequency (continuous electronic trend, per-shift manual reading, or both) based on your facility monitoring system’s capability and your risk assessment.
3. Point the exception handling section to your real deviation management and product impact assessment procedures.
4. If your facility monitoring system already continuously logs and alarms electronically, use this log as the shift-level review and verification record rather than the primary data source, and reference the electronic trend data explicitly.