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CIP Interrupted – Initial Guidance

Use this guide when a CIP Interrupted alarm is active, or when a CIP sequence cannot be started or is stopped automatically due to CIP tank level conditions. This guidance applies to LiqTech Crossflow systems where CIP sequences are stopped before completion or prevented from starting.

What the alarm means

A CIP Interrupted alarm indicates that a CIP sequence did not complete as intended.

As a result, cleaning chemicals may still be present in the crossflow loop, membrane housings, or associated piping.
The chemical state of the system must therefore be considered unknown until verified.

This alarm does not indicate membrane damage.

LiqTech membranes are chemically inert and can tolerate the full approved pH range used for CIP.
The purpose of this alarm is not to protect the membranes, but to ensure that the system is handled correctly while chemicals may still be present.

In practice, the alarm simply means that the system must be handled as if CIP chemicals may still be present in the loop.

How the alarm is acknowledged

To acknowledge and exit the CIP Interrupted alarm state:

  • Press and hold the Reset button for more than 10 seconds

This clears the alarm condition, but does not change the chemical condition of the system.

Why this alarm requires attention

CIP Interrupted is not a dangerous alarm, and it does not indicate a fault condition.

However, after the alarm is cleared, it cannot be assumed that the system is chemically neutral.
The operator must therefore act with awareness until the system has been flushed or a new CIP has been completed.

Typical actions after a CIP Interrupted event

In most cases, one of the following actions is sufficient:

  • Flush the system until permeate returns to neutral pH

  • Remove the cause of the interruption and restart the CIP sequence

Which action is appropriate depends on where in the CIP sequence the interruption occurred.

Most common cause

The most common cause of a CIP Interrupted condition is:

  • Low-Low Level or Empty condition in the CIP tank

When this occurs, the CIP sequence is stopped automatically to protect the CIP pump and prevent air ingress.

The same CIP tank level conditions can also prevent a CIP sequence from starting at all, even if the operator attempts to initiate CIP manually.

pH verification and personal safety

If pH measurements are taken from sample points after a CIP interruption:

  • Always follow site-specific safety procedures

  • Wear appropriate PPE

  • Treat all samples as potentially chemically active until neutrality is confirmed

Maintenance considerations

Before performing maintenance on the system after a CIP Interrupted event, it must be confirmed that:

  • the system has been flushed appropriately, or

  • a full CIP sequence has been completed

Until then, the chemical state of the system should be considered unknown.

Alarm ID reference – CIP Interrupted and CIP tank level protection

The following alarm references are examples observed in LiqTech Crossflow systems.
They are provided to help identify alarm context when a specific alarm ID or alarm text is referenced.

Other project-specific alarm IDs may exist.

CIP Interrupted

MK6

  • 52 – CIP interrupted, can be chemicals in the loop

This alarm indicates that a CIP sequence was stopped before completion and that chemicals may still be present in the loop.

CIP tank level protection (digital level alarms)

On MK6 systems, CIP tank level is typically monitored using digital level switches in the CIP module (e.g. CA / CB).

Alarms with texts such as:

  • CIP tank low-low

  • CIP tank empty

  • CIP tank level too low to start CIP

are commonly responsible for:

  • interrupting an active CIP sequence

  • preventing a CIP sequence from starting

The exact alarm IDs and wording depend on system configuration and project implementation.

Important note on alarm references

The alarm references listed above are examples only.

This guidance may also apply to other alarms with similar texts indicating:

  • CIP stopped

  • CIP cannot start

  • CIP tank empty

  • CIP tank low-low

depending on system generation and configuration.

Key takeaway

  • CIP Interrupted means CIP did not finish

  • Membranes are not damaged

  • The system should simply be handled as if chemicals may still be present

  • The most common cause is low-low or empty CIP tank

  • CIP may need to be flushed or restarted before normal operation