Site Quantities — How Calculations Work
Overview
This page explains the calculation logic behind the Site Chemical Quantity Aggregation feature — how Tellus converts your inventory into site-level chemical totals and determines threshold compliance.
Unit Conversions
All quantities are normalized to pounds (lbs) for weight and gallons (gal) for volume using standard conversion factors:
Weight Conversions (to pounds)
| Unit | Conversion Factor |
|---|---|
| lbs | 1.0 |
| oz | 0.0625 |
| kg | 2.2046 |
| g | 0.0022 |
| mg | 0.0000022 |
| ton | 2,000.0 |
Volume Conversions (to gallons)
| Unit | Conversion Factor |
|---|---|
| gal | 1.0 |
| L (liter) | 0.2642 |
| qt (quart) | 0.25 |
| pt (pint) | 0.125 |
| fl oz | 0.0078 |
| mL | 0.000264 |
| cu ft | 7.4805 |
Weight ↔ Volume Conversion
To convert between weight and volume, Tellus uses chemical-specific densities (in lbs/gal). When no density is available for a specific chemical, water density (8.34 lbs/gal) is used as the default.
Quantity Calculation Per Chemical Component
For each inventory item, the calculation is:
Total item quantity = container size × number of containers
Chemical quantity = total item quantity × conversion factor × concentration percentage
Concentration is taken from the SDS composition data — the percentage of each chemical in the product.
- When the SDS provides a concentration range (e.g., 50–75%), Tellus uses the upper bound (maximum concentration). This is the conservative approach for regulatory reporting — it ensures you never underestimate quantities for Tier II filing or fire code compliance.
- When the SDS provides a single concentration value, that exact value is used.
- If no concentration is available for a chemical component, it is treated as 100% of the product.
Simple Example
You have 3 bottles of a cleaner, each 1 gallon, and the SDS shows it contains 15% acetone:
- Total item quantity = 1 gal × 3 = 3 gallons
- Acetone contribution = 3 gal × 0.15 = 0.45 gallons
- Acetone in pounds = 0.45 gal × 6.56 lbs/gal (acetone density) = 2.95 lbs
Multi-Component Example
Consider an Isocyanate Activator product used in an automotive paint shop:
| Property | Value |
|---|---|
| Container size | 5 gallons |
| Inventory quantity | 100 containers |
| Total product volume | 5 gal × 100 = 500 gallons |
The SDS lists 5 chemical components with concentration ranges:
| CAS Number | Chemical Name | Concentration Range | Used for Calculation |
|---|---|---|---|
| 28182-81-2 | Hexamethylene diisocyanate, oligomers | 50–75% | 75% (max) |
| 79-20-9 | Methyl acetate | 10–20% | 20% (max) |
| 103-09-3 | 2-Ethylhexyl acetate | 0–10% | 10% (max) |
| 108-83-8 | Diisobutyl ketone | 0–10% | 10% (max) |
| 19549-80-5 | Methyl isoamyl ketone | 0–3% | 3% (max) |
Each chemical's site quantity is calculated independently:
| Chemical | Calculation | Site Quantity (gal) |
|---|---|---|
| Hexamethylene diisocyanate | 500 gal × 75% | 375.00 gal |
| Methyl acetate | 500 gal × 20% | 100.00 gal |
| 2-Ethylhexyl acetate | 500 gal × 10% | 50.00 gal |
| Diisobutyl ketone | 500 gal × 10% | 50.00 gal |
| Methyl isoamyl ketone | 500 gal × 3% | 15.00 gal |
Each of these appears as a separate row on the Site Quantities screen, grouped by CAS number. If other products at the same site also contain any of these chemicals, their quantities are summed together.
Why use the maximum concentration? SDS concentration ranges reflect manufacturing variability — a batch might contain anywhere from 50% to 75% of an ingredient. For regulatory reporting (Tier II, fire code), using the upper bound ensures your facility is compliant even in the worst case. This is standard practice recommended by OSHA and EPA guidance.
Tier II Thresholds
EPA EPCRA Section 312 requires facilities to file annual Tier II reports for hazardous chemicals stored above these thresholds:
| Chemical Type | Threshold |
|---|---|
| General hazardous chemicals | 10,000 lbs |
| Extremely Hazardous Substances (EHS) | 500 lbs |
In the UI, a green checkmark means the chemical is below the threshold. A red indicator means it exceeds — and the chemical should be included in your Tier II report.
Fire Code Thresholds
Based on the International Fire Code (IFC) Table 5003.1.1(1) — Maximum Allowable Quantities per control area for indoor storage:
Flammable & Combustible Liquids
| Class | Description | Max Qty (gallons) |
|---|---|---|
| IA | Flash point < 73°F, boiling point < 100°F | 30 |
| IB | Flash point < 73°F, boiling point ≥ 100°F | 120 |
| IC | Flash point 73–100°F | 120 |
| II (Combustible) | Flash point 100–140°F | 120 |
| IIIA (Combustible) | Flash point 140–200°F | 330 |
| IIIB (Combustible) | Flash point ≥ 200°F | 13,200 |
Oxidizers
| Class | Max Qty (lbs) |
|---|---|
| 1 | 4,000 |
| 2 | 250 |
| 3 | 10 |
| 4 | 1 (any amount requires a permit) |
How Fire Code Class Is Determined
Tellus maps GHS hazard classifications from the SDS to International Fire Code categories:
| GHS Hazard Class | GHS Category | Fire Code Category | Fire Code Class |
|---|---|---|---|
| Flammable liquid | Category 1 | Flammable Liquid | IA |
| Flammable liquid | Category 2 | Flammable Liquid | IB |
| Flammable liquid | Category 3 | Flammable Liquid | IC |
| Flammable liquid | Category 4 | Combustible Liquid | II |
| Oxidizer | Category 1 | Oxidizer | 4 |
| Oxidizer | Category 2 | Oxidizer | 3 |
| Oxidizer | Category 3 | Oxidizer | 2 |
Hazard Summary Aggregation
The Hazard Summary tab groups all chemicals by their fire code classification and totals the quantities. The % of Limit is calculated as:
% of Limit = (total quantity for this hazard group ÷ fire permit limit) × 100
This tells you at a glance how close each hazard category is to the fire code maximum — 50% means you're using half your allowable capacity, 100% means you've reached the limit.