What to record at a dry-block verification
A useful verification record gives the next technician enough information to repeat the check, explain the result and reconnect it to the plant trend.
A service record says “verified” with a tick beside it. Months later, another technician needs to understand whether a changed result followed maintenance, a different block or a genuine shift in the instrument response. The tick tells them a check happened. The value of the record is in the detail that lets someone reproduce the same check and understand the decision that followed.
Keep the reference value with the instrument and block
A dry block is a secondary standard used to check the instrument response. It has to be assigned a reference value using the applicable procedure before it can be used for subsequent comparisons. Record the instrument identifier, the block identifier used at your site, the assigned value and its units, and when and how that value was established. If the site has more than one block, the record should make it clear which one was fitted for the check.
This matters after work on the instrument or when a block moves between locations. A value copied from an earlier service sheet may refer to a different analyser or configuration. The PMA verification demonstration shows the assignment of a reference value. Keep the manufacturer’s operating instructions with the site procedure so the next technician can check the sequence.
Record what the instrument displayed and what you did
Write down the observed result, the reference you compared it with and the outcome under the site’s acceptance procedure. The actual result is valuable even when the instrument passes. A series of recorded values can help the service team see a gradual change, whereas a column of ticks shows only that each check met its applicable criterion at the time.
If the initial check is outside the acceptance criteria, preserve it along with any follow-up result. For example, a technician might inspect the block seating and instrument condition, then repeat the check as the site procedure allows. Keeping both observations and the work between them gives a colleague a way to interpret the outcome. A single final reading leaves that sequence out of the record.
Give verification and calibration separate entries
Verification checks the response against a known reference. Calibration uses the applicable primary standard procedure to establish the instrument’s response. If a verification prompts a calibration, record those as distinct events. Note the primary standard and the relevant calibration details, then record any checks made afterwards according to the site procedure.
The difference becomes important when reviewing a change over time. If the record simply says “block checked and instrument adjusted”, the next reviewer cannot tell what was observed before the adjustment or which procedure established the new baseline. The verification and calibration guide explains how to plan access for both tasks, and the PTV 1000 calibration demos show the primary-standard procedures.
Reconnect the service record to the live trend
Once the check is complete, restore the normal sample path and confirm the analyser is receiving a representative sample. Record when the instrument was taken out of service and when it resumed normal monitoring. Where the historian shows a maintenance state or allows annotations, use the site’s normal practice to flag the affected period. This helps operators distinguish service activity from a change in the process.
The most useful record follows the job in order. It identifies the instrument and reference, shows what the technician observed, records any corrective work and marks the return to live sampling. Keep it where both the service team and operations can find it. At the next check, the technician has a comparable result and a clear picture of what happened in between.
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