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Sent: Tuesday May 17, 2020 4:14 PM
Subject: Frit problem

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 less than 100 plates, which is unacceptable. 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 attached a diagram of a frit for reference.

Sent: Tuesday May 17, 2020 4:14 PM
Frit problem fixed—W49983A2 is ready for use (diagram attached)

Hi Tom:

Good news: W49983A2 is ready for use
The broken top frit was replaced, 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. The results of the last test were good: HETP at 0.043 cm/plate and 230 plates.

My report and solution follow—frit diagram attached for reference
Before column use, the HETP results were acceptable: 0.05 cm/plate and 198 plates.

Subsequent tests failed: We detected trapped air
Between regeneration and WFL rinse, air was pumped into the headspace. The HETP test results were unacceptable with fewer than 100 plates.

Pumping WFL through the column did not help
We repacked the column with WFL. Most of the air was pushed through the top column tube. HETP tests were again unacceptable so we retried the procedure.

Problem identified —resin was passing by the top frit
While pumping WFI through the column a second time I noticed
resin flowing into tubing at column inlet
the top frit mesh torn away from support piece.

Actions taken: I replaced the malfunctioning BS-II frit
In case we need to repeat this in the future, here are the steps I took:
1. replaced the top frit
2. reslurried the resin
3. repacked the column
4. ran an HETP test.

Warm regards,