Guidance on Control Voting and Group Coverage

As there are several ways in industry to set alarm and coverage targets, Detect3D has multiple settings to enable or change which affect coverage. This section will go over how Control Voting Logic, Acoustic Detector Voting Logic, Detector Groups, and Group Coverage Limits all affect each other and the resulting coverage calculation.

 

Definitions

Control Voting Logic - Set in a risk grades' performance requirements section, this option changes the 2ooN+ coverage calculation based on input gas cloud sizes for low alarm and high alarms. Available options are: Lo-Lo (default), Lo-Hi, and Hi-Hi. See this section for more information on control voting logic. This option only applies to gas detection.

Acoustic Detector Voting Logic - Set in a risk grades' performance requirements section, this option affects how acoustic devices contribute to 1ooN and 2ooN+ coverage calculations. Available options are: contribute to 1ooN Only, both 1ooN and 2ooN+ (default), or 2ooN+ Only. 

Gas Cloud Size Low Alarm - Set in a risk grades' performance requirements section, it is the diameter of the gas cloud size used for the low alarm setting. 

Gas Cloud Size High Alarm - Set in a risk grades' performance requirements section, it is the diameter of the gas cloud size used for the high alarm setting. This value is usually smaller than the low alarm size.

Detector Group - Defined from the Add Items Tab and managed with the Detector Group Manager, users can combined multiple flame or gas detection devices into a group. This can be useful for toggling items in bulk, such as labels, FOV/FOIs, and visibility. Other uses are for disabling detectors in bulk or simulating detector loops.

Group Coverage Limit - Found in the Project Settings under the Gas Mapping Analysis section or Fire Mapping Analysis sections, this option places a limit on the coverage that can be achieved by a detector group. Options are No Limit (default), Limited to 1ooN, and Limited to 2ooN. No limit here means assigned groups do not affect coverage. Limited to 1ooN means the devices in that group only contribute to 1ooN coverage within that group. Overlap with devices in another separate group will still contribute to 2ooN+ coverage. Limited to 2ooN means the devices in that group only contribute to 1ooN and 2ooN coverage within that group (excluding 3ooN, 4ooN, etc). Goal of this capability is to simulate different detector loops and the various coverage combinations that can exist in a project.

 

 

Assumptions:

We have added options for various control voting logic to maintain our goal of being applicable to as many internationally recognized standards and guidelines as possible. However, not all nuances of these combinations of control voting, acoustic devices and group coverage limits (or looping) are defined in standards, meaning at some point assumptions need to be made for clarity and simplicity of the complex set of combinations. Below is a list of the assumptions used in developing these options in Detect3D:

  • Acoustic devices are always considered as a lo alarm when used with control voting logic

    • The Lo alarm of the acoustic device still contributes to Lo-Hi voting logic for 2ooN coverage as long as it is not limited by Group Coverage Limits.

    • This means if the voting logic is set to Hi-Hi then acoustic devices do not contribute to 2ooN coverage levels

    • If the control voting logic is set to Hi-Hi and the acoustic contribution is set to 2ooN+ Only, then the result is the acoustic device is not contributing to 1ooN or 2ooN - providing no coverage.

  • The 1ooN Only setting for Acoustic Detector Voting Logic sets the acoustic devices to only contribute to 1ooN coverage. Overlap of an acoustic detector with a gas detector will not contribute to 2ooN+ coverage values using this setting.

  • For Lo-Hi Control Voting Logic

    • Regardless of how many overlaps of Lo alarm regions there are, only 1 will count towards 2ooN coverage.

    • Overlap of Lo-Lo-Hi, Lo-Hi-Hi, and Hi-Hi regions are all still considered only 2ooN. Only additional Hi regions would contribute to 3ooN+. For example, regions with Lo-Hi-Hi-Hi would be considered as 3ooN. 

  • Group Coverage Limits

    • Limits applied only within the groups themselves. 

    • Devices without a defined group are not constrained by this limitation and will contribute to coverage in the default manner.