The Digital Divert Control System DD‑23 uses the displayed concentration value in its decision logic.
| CAUTION Do not use the external hold functionality with a DD‑23. It could render the system unsafe by freezing the measurement result. |
HOLD DURING WASH must be used with DD‑23. Otherwise the signal damping combined with low nD values caused by the wash process may give erroneous information to the DD‑23 after the wash is over.
The selection of tolerance time with DD‑23 requires a careful risk analysis. The use of the tolerance time functionality does not slow down the response of the instrument when the instrument is in NORMAL OPERATION. However, it slows down the malfunction alarm in DD‑23 in case the process pipe becomes empty or some other reason makes the optical image impossible to interpret. The recommended value for tolerance time is 5 s when a DTR is used in a DD‑23 system.