First of all, the HETP test result prior to column use in W49983A2 was .05 cm., resulting in 198 plates. Between regeneration and WFI rinse, some air was pumped into the headspace between the top frit and resin bed. We tried an HETP test and got unacceptable results (less than 100 plates). We then pumped WFI up through the column as a common method to displace air out through the top column tube. Most of the air was displaced and the column repacked with WFI. Subsequent HETP tests were also unacceptable. We again pumped WFI up through the column to displace an air bubble and when the resin came in contact with the top frit I observed resin passing into the tubing at the immediate column inlet. When I removed the top flow assembly I found the top frit mesh to be broken away from the support piece that it's molded to explaining why resin was able to pass by the top frit. I replaced the top frit, reslurried the resin and repacked the column. I ran an HETP test with very good results, HETP=0.043 cm. and 230 plates. The bottom frit is intact and no resin has been lost. Since the resin was exposed to the air the column was re-regenerated and then stored. The column is now ready for use in the next batch. I've put a diagram of a frit in your mailbox for reference.

Notes

No visual design to guide reader

With no headlines labeling content, the reader must read every word of the text. If both parties need to discuss the message, it will be awkward to refer to information.

Vague subject line

"Frit problem" could refer to half a dozen topics. The reader must identify the part of the problem that is important to the reader.

Long sentences

Shorter sentences are more conversational and easier for your readers to understand quickly; this is especially important when sentences contain technical language. Sentences in general technical writing shouldn't be longer than 20 words.

Wordiness

Wordy sentences are confusing and difficult for the reader to follow. Streamlining awkward sentences increases clarity.

Key point buried

The main point is hidden, so the reader is likely to miss it entirely. Even simple messages should begin with a clear "bottom-line" statement.

Unclear next steps

There's no clear action plan to tell the reader what he's supposed to do next.

Tom,

GOOD NEWS: WE'VE REPLACED THE BS-II FRIT
Here are the events leading to the malfunction.

HETP RESULTS OK BEFORE COLUMN PROBLEMS
Original lab test showed

• HETP at 0.05 cm/plate
• 198 plates.

This amount was acceptable.

SUBSEQUENT TESTS FAILED: WE DETECTED TRAPPED AIR
Between regeneration and WFI rinse, air was accidentally pumped into the headspace. This area is between the top frit and the resin bed. An HETP test revealed unacceptable results: fewer than 100 plates.

We tried to displace the air by pumping WFI up through the column. Most of the air was pushed through the top column tube. We repacked the column with WFI. HETP tests were again unacceptable so we retried the procedure.

DISCOVERY OF KEY PROBLEM
While pumping WFI through the column a second time I detected

• resin flowing into tubing at column inlet
• top frit mesh torn away from support piece.

ACTIONS TAKEN
I took the following steps:

1. replaced the top frit
2. reslurried the resin
3. repacked the column
4. ran an HETP test.

CURRENT STATUS
The bottom frit is intact and no resin has been lost. The column has been regenerated and stored; it is ready for use in the next batch.

Notes

Key message in the subject line

The bottom line is in the subject line so the reader immediately knows what the message is about.

Positive approach

Rather than focusing on the problem up front, the writer explains that it has been fixed. After reading that at the beginning, the reader will be more receptive to the message.

Logical sequencing

It's easy for the reader to follow the chronologically sequenced events leading to the solution.

Clear, concise explanation

Shorter sentences and clearly defined terms ensure that even a nontechnical reader could understand what happened.

Bullets and white space to guide the reader

Headlines, bullets, and white space all help important points stand out so the reader can find information quickly and easily. Dense text is much more difficult to read.

Action words

Using strong verbs energizes the message and helps the writer clearly explain how he fixed the problem.

Numbers to show the sequence of events

Numbering the events ensures that the reader understands the process and that it could be duplicated in the future if necessary.

Informative headlines

The reader wants to know what happened and what's been done about it. The headlines guide the reader to find answers easily and contribute to the logical flow of information.