Oekotech

Oil Sorbent Pad Quantity for a Spill (Absorbency Ratio & Field Factor)

A pad that holds twenty times its weight in the lab holds less on a wet floor. Count pads on the field figure.

Spill Volume & liquid
L

Free liquid left after any pumping or skimming. Estimate it from the pool area and depth if there is no meter reading.

kg/m³

From the safety data sheet. Most fuel and lubricating oils fall between 800 and 950; water is 1,000.

Sorbent From the pad data sheet
g

One pad, dry. A 400 x 500 mm meltblown pad at 300 g/m² weighs 60 g.

g/g

Grams of oil held per gram of sorbent in a sorbent performance test (ASTM F726), or the maker's "absorbs X times its weight" claim for a liquid like yours.

%

Share of the lab capacity a pad reaches on site. Pads are lifted before they saturate, oil drains back as they are carried, and the edges stay dry. Use 100 only if you have measured it.

pads
pads

What the nearest kit holds. The shortfall is what to fetch or order.

Pads to Put Down

— pads

Liquid mass divided by what one pad holds at the field factor, rounded up

Quantities

Liquid Mass to Recover
— kg
Capacity per Pad at the Lab Ratio
— kg
Capacity per Pad at the Field Factor
— kg
Litres Held per Pad in the Field
— L
Bales to Open
— bales
Pads Short of the Kit
— pads
Dry Sorbent Used
— kg
Saturated Waste Mass
— kg
Waste Mass per kg of Liquid
— kg/kg

The absorbency ratio is the sorbent's figure, not the tool's: a sorbent performance test (ASTM F726 for adsorbents such as meltblown polypropylene, ASTM F716 for absorbents) reports grams of oil held per gram of sorbent for a stated oil, and makers quote it as "absorbs X times its weight". The ratio measured with a light oil does not carry over to a heavy one, nor an oil-only pad's ratio to a water-based liquid. The field factor is a planning allowance for pads lifted early, drain-back and dry edges; it is not a tested property. The saturated waste mass is the dry sorbent plus the liquid it holds; what that waste is classed as, and how it is disposed of, follows local rules on the liquid spilled. **This sizes the sorbent for the recovery step; it does not plan containment, drainage protection or a pump-first response.**

Oil Sorbent Pad Quantity for a Spill (Absorbency Ratio & Field Factor) — free, with the formula and a worked example, at Textile School.