Questions regarding the setting of DCS alarm values

Under normal circumstances, control point alarms are the primary means of notification, with display alarms serving as a supplementary mechanism; these can be used to verify the accuracy of the data!

We do the same: if there are two alarms, it goes to Hi and HH at the control point; if there are more alarms, it is set on the sub-display value. For temperature monitoring of critical systems, it is also necessary to add the ZMVC function for monitoring the deviation comparison between two temperature points.

I think alarms should be set for both of these. For the operator, what he sees on the DCS screen is the TIC; therefore, it is essential to set an alarm value for the TIC. In most cases, TI does not provide a separate display panel on the DCS screen; however, it is still advisable to have an alarm function, and the set values should be consistent with those of the TIC.

In my opinion, the alarm values should be set at the TI, that is, at the temperature measurement point; generally, there is no need to set alarms at the TIC (although this can be done depending on process and safety requirements). At least that’s how our company’s DCS (Zhejiang Zhongkong) is configured. Alarms may be set on some control valves, but this is the exception.

It is generally used for display purposes in order to facilitate regulation and control; the indicator gauge TI can be used for alarms. This depends on the actual conditions at the site with those two thermometers – choose the one that is more sensitive to temperature. It’s also possible to use both of them

It is not possible to determine the direction of flow of the medium; having two temperature transmitters on one pipeline constitutes a luxury feature – usually, there is one transmitter for remote monitoring and one for local monitoring. The alarm settings are actually soft settings; it is possible to set those that meet the process requirements or to set all of them.

The TIC is a temperature controller (it cannot be used directly for measuring pipe temperature); the pipe connected to it must have some form of protection or a temperature transmission system with on-site display (this is usually not indicated in the drawings). The alarm values are generally set using the TIC； The TI later on is used for temperature compensation.

Personal understanding: The setting of alarms is generally the responsibility of process engineers, and the purpose of setting these alarms is to ensure that the factory’s processes operate efficiently. When a temperature alarm is triggered, will it have an impact on the upstream and downstream systems? (The simplest way is to refer to the risk matrix); if the impact is minimal, there is no need to set it up. Both measure the same location and can be set accordingly. It is best to place it on the display; the purpose of the control circuit is to enable control. If there is only one instrument involved in control, it can be installed on the control circuit. Since I’m not familiar with the entire process, I don’t understand why two instruments are installed here. Shouldn’t there be one instrument for local use and another for remote monitoring? Maybe it was drawn incorrectly; I’m waiting for an expert to explain this. Note: Do not set up alarms repeatedly, as this will interfere with the operators; there is no need to do so.

Under normal circumstances, control point alarms are the primary form of alerting, with display alarms serving as a supplementary mechanism; in addition, a deviation alarm is set between the two.

Thank you. We have two thermocouples on site; one of their signals is sent to TIC, while the other signal is sent to TI. I also believe that the alarm threshold should be set at TI. The main function of TIC is circuit control, and even if TIC fails, setting an alarm at TI along with human intervention can provide another layer of protection, reducing the probability of accidents by an order of magnitude