HON Leak - Valves – LDARtools

What this report does

Shows the valve leak rate for each selected unit across up to four historical monitoring periods, plus a rolling average rate. Each period's leak rate is calculated from the valves monitored, leaks found, and pre-existing DOR adjustments for that period, using the HON (Hazardous Organic NESHAP) 1% DOR threshold.

Unlike the per-component detail in the HON Leak Report, this report produces one summary row per unit — making it the primary tool for tracking valve leak rate trends and confirming rolling average compliance over time. This report is in the Leak folder on the Reports tab.

When to use it

Reviewing valve leak rate trends across multiple monitoring periods.
Confirming that a unit's rolling average leak rate is within the HON threshold.
Preparing period-over-period summaries for regulatory reporting.

Parameters

Parameter	Description	Required	How it filters
Regulation	The regulation to report on	Yes	Only valves mapped to this regulation are included
Unit Type	Whether to filter by Process Unit or Location Unit	Yes	Determines which unit list populates
Units	One or more units to include	Yes	One output row per selected unit
Apply 0.67 Net Deactivated Credit	Whether to apply the 0.67 deactivation credit to the denominator	Yes	When Yes, net deactivations during each period are multiplied by 0.67 and added to the denominator
Select the last Day of the latest desired Period	The last day of the most recent monitoring period to include	Yes	The report calculates the selected period and the preceding periods working backward from this date

Periods are calculated backward from your selected date. Enter the last day of the most recent period you want to see. The report uses the regulation's monitoring schedule to determine the period boundaries automatically.

Columns

Column	What it shows	Format / Notes
Unit	The unit name	Text
Monitoring Period 1	Valve leak rate for the oldest period in the window	Decimal (2 decimal places), as a percentage; blank for units with non-Annual monitoring frequency
Monitoring Period 2	Valve leak rate for the second oldest period	Decimal (2 decimal places); blank for non-Annual units
Monitoring Period 3	Valve leak rate for the second most recent period	Decimal (2 decimal places)
Monitoring Period 4	Valve leak rate for the most recent period	Decimal (2 decimal places)
Rolling Average Leak Rate	The rolling average leak rate across the displayed periods	Decimal (2 decimal places); calculated differently depending on monitoring frequency — see below
Frequency	The monitoring frequency assigned to this unit under the regulation	Text; e.g., "Y" (Annual), "SA" (Semi-Annual)

What's included and excluded

Included:

Only valves (component type Valve) mapped to the selected regulation.
Only components in the selected unit(s).
Only M21 inspections with an Initial, Standard, or Periodic inspection reason (D30 and D90 delayed-monitoring inspections are excluded from the Monitored count).
Components with pre-existing DORs (DORs open before the start of the period) are counted separately and factored into the threshold calculation.

Excluded:

Non-valve component types.
Exempt valves (components with an Exempt inspection frequency under the regulation).
Heavy liquid (HL) valves.
Unsafe-to-Monitor (UTM) and Difficult-to-Monitor (DTM) components that were not actually inspected during the period (unless the unit's monitoring frequency is Annual).
Leaks closed with a Mis-Identification close reason.
Components not mapped to the selected regulation.

How key values are calculated

Monitoring periods

The report retrieves up to four completed monitoring periods working backward from the date you enter. For Annual units, all four periods are shown. For units with a shorter monitoring frequency (Semi-Annual, for example), only two periods are shown (in the Period 3 and Period 4 columns) and Period 1 and Period 2 are blank.

Leak rate per period

Each period's leak rate uses the same formula as the HON connector and pump reports, adjusted for the 1% valve threshold:

Denominator = Monitored + Credit (Times 0.67) + Pre-Existing DORs
Excess DORs = max(0, Pre-Existing DORs − 1% of Total Valves)
Numerator = Leaks Found + Excess DORs
Leak Rate = (Numerator ÷ Denominator) × 100

The 1% threshold is calculated from the total valve population (all active valves in the unit at the end of the period). Pre-existing DORs within the 1% allowance are absorbed into the denominator without penalty; any amount above that becomes Excess DORs and is added to the numerator.

Rolling Average Leak Rate

The rolling average is calculated differently depending on the unit's monitoring frequency:

Annual units (4 periods shown): The rolling average is the average of the three lowest leak rates across the four periods. This reflects the HON provision that allows a facility to exclude the highest-rate period from the rolling average calculation.
Non-Annual units (2 periods shown): The rolling average is the simple average of the two period rates shown.

Best-3-of-4 selection

For annual monitoring programs, the rolling Leak% is calculated using the best three of the four most recent periods. The period with the highest Leak% is excluded from the average. This gives facilities credit for one anomalous period while still requiring consistently low leak rates across the remaining three.

Tips and common questions

"Monitoring Period 1 and Period 2 are blank for some units." Units with a non-Annual monitoring frequency only show two periods (in columns 3 and 4). The blank columns are expected — those periods do not apply to that unit's monitoring schedule.
"The rolling average for my Annual unit seems lower than the simple average." For Annual units, the rolling average excludes the highest-rate period, using only the three lowest. This is the HON-prescribed calculation method and will produce a lower result than a straight average of all four periods.
"How do I know which calendar dates each period covers?" The period boundaries are determined by the regulation's monitoring schedule and the end date you entered. If you need the exact dates, run the HON Leak - Connectors or HON Leak - Pumps report for the same regulation and units — those reports include Period Start and Period End columns.
"The 0.67 deactivation credit option — when should I apply it?" Apply it when your facility has had a net reduction in the valve population during the period (more deactivations than activations). The credit adjusts the denominator upward, which lowers the effective leak rate. Apply it consistently across all periods for the most accurate trend comparison.
"A unit I selected does not appear in the output." Units with no monitored valves mapped to the selected regulation will not produce a row. Confirm that the unit has valves with the regulation assigned and that monitoring occurred during the period.
"Period 1 is the oldest period, not the most recent." The period columns are ordered with the oldest period on the left (Period 1) and the most recent on the right. When reading the trend across periods, read right-to-left to see the most recent performance first.
"What happens to DORs above the 1% threshold?" DOR records are subject to a 1% threshold — if the number of open DORs exceeds 1% of total valves, the excess DORs are added to the numerator. This means that having many valves on Delay of Repair can increase your reported Leak%, even if those components have not had a new leak found in the current period.

Sample output

Report run for Example Facility, Regulation: HON, Unit Type: Location Unit, Credit: No, Period end date: 12/31/2025.

What the rows illustrate:

Unit A — Annual unit with four periods shown. The rolling average (0.62) is the average of the three lowest rates (0.50, 0.60, 0.75), excluding the highest (1.20). All four rates are below the 1% threshold.
Main Plant — Semi-Annual unit; only two periods are shown (Period 3 and Period 4). The rolling average is the simple average of the two rates shown: (0.80 + 1.10) ÷ 2 = 0.95.

Output format

One row per unit. Suitable for on-screen viewing, PDF, and Excel export.

Related reports

HON Leak Report — the primary HON leak report; shows full per-component leak detail for all component types rather than summarized rates.
HON Leak - Connectors — per-period connector leak rate summary; shows the full breakdown columns (Monitored, Act, DeAct, Leaks Found, etc.) for a single period.
HON Leak - Pumps — per-period pump leak rate summary; uses a different formula that subtracts leaks found on newly added pumps.