About Fire Glass Calculation
The **Fire Glass Calculator** determines the quantity of fire glass or lava rock required to cover the burner pan of a fire feature to a desired depth. The calculation is based on the **volume** of the space and the **density** of the material.
Key Formulas Used
The material required is calculated using a standard formula that converts the volume (Area × Depth) into weight, utilizing an industry density factor. $$\text{Rectangular (Imperial):} \quad \text{Weight (lbs)} \approx \frac{\text{L} \times \text{W}}{144} \times \text{D} \times 15$$ $$\text{Circular (Imperial):} \quad \text{Weight (lbs)} \approx \frac{\pi \times (\text{Diameter}/2)^2}{144} \times \text{D} \times 15$$ Where L, W, D are in inches. $144$ converts in² to ft². $15$ is the density factor (lbs/ft²/in).
Why Use Fire Glass?
Benefits
- **Aesthetic Appeal:** Reflective surfaces enhance the flames' glow.
- **Clean Burning:** Does not melt, smoke, or degrade over time.
- **Heat Retention:** Radiates heat effectively long after the gas is off.
Material Comparison
- **Fire Glass:** Lighter, more decorative. Density factor $\approx$ 15 lbs/ft²/in.
- **Lava Rock:** Cheaper, heavier, used as a base filler. Density factor $\approx$ 20 lbs/ft²/in.
- **Depth:** Standard fill depth is **2 inches (5 cm)** over the burner.
Tips for Ordering and Installation
Preparation
- **Pre-fill with Lava Rock:** If your pit is very deep, save money by filling the lower portion with cheaper lava rock or non-combustible base material, then capping with 1-2 inches of fire glass.
- **Measure Inside:** Always measure the interior dimensions of the fire pit tray or burner pan, not the outer edge of the pit.
- **Burner Type:** Ensure you are only filling over the burner pan, not the entire pit surface, for proper gas flow.
Ordering
- **Round Up:** Always round up to the nearest whole bag (usually 10 lbs or 5 kg) to ensure complete coverage. The calculator handles this automatically.
- **Material Size:** Larger glass sizes (1/2" - 3/4") allow better air/gas flow than smaller sizes, which is crucial for burner efficiency.
- **Cost:** Fire glass can range from **₹200 to ₹500 per pound** depending on color, shape, and quality.
Installation Time Estimate
Small Pit (under 24")
5-10 minutes
Easy pour
Medium Pit (24"-36")
10-20 minutes
Requires leveling
Large/Custom Pit (40"+)
20-40 minutes
Requires staging material