Self-checking of pure and ultrapure water systems: Dealing with Long Downtime

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Self-checking of pure and ultrapure water systems: Dealing with Long Downtime

Self-checking of pure and ultrapure water systems: Dealing with Long Downtime

How did you find the key points concerning management of pure and ultrapure water systems in “Regular Inspections” in the previous column? This column will introduce “Dealing with Long Downtime,” matters to be carried out when equipment is unused for five days or longer.

Dealing with Long Downtime

1. Turn off power to the equipment and shut off the water supply source.
This prevents water leaks and backflow.

2. Empty the tank.
→This prevents the growth of bacteria.
Water stored in the tank cannot be used after a vacation period.
To reduce work following a vacation period, drain the water beforehand.

 【How to drain water】
 Drain water from the tank cock or the drain plug.
 * It may not be possible to drain water completely from the tank cock. Using the drain plug may be preferable.   Do not forget to close the drain plug afterward.

3. Drain water from the pipes.
→This prevents freezing and bacterial growth. If you have any concerns about draining the pipes, please consult your dealer.

Dealing with Long Downtime

Perform sufficient circulation treatment and blowing of treated water before use, and perform dispensing after the water quality has risen.
→This step is performed because the TOC value does not readily decrease in ultrapure water immediately after the equipment is started or in primary generated water.

Examples of equipment trouble

Trouble: The equipment was temporarily stopped due to water supply-related construction work. Afterward, the water quality did not return to normal.
Cause: A large amount of impurities contained in the water supply following construction work was released into the equipment.

◎ Solution: Disconnect the equipment from the water supply before the construction work, let water sufficiently flow following the construction work, and then connect the water supply to the equipment. When construction work is performed in the facility, discard initially flowing water, then connect the equipment.


The above introduced key points in “Dealing with Long Downtime,” by which persons using pure or ultrapure water can inspect equipment on their own.

  1. Actions before long downtime
  2. Actions following long downtime

The columns so far have introduced key points concerning equipment management in “Routine Inspections,” “Regular Inspections,” and “Dealing with Long Downtime.”

Use this information as reference to properly manage equipment and reduce the risk of interruptions in analysis.

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