BOD Bottles

The BOD bottle is purpose-built for one of the standard tests of water quality: measuring how much oxygen micro-organisms consume in a water sample over a fixed period (typically five days at 20 °C). The whole test depends on excluding atmospheric oxygen, so the bottle's design is all about an airtight, bubble-free seal.

Its tapered ground-glass stopper displaces all the air as it is inserted, and the flared mouth lets a little water sit around the stopper as a water seal, keeping atmospheric oxygen from diffusing in during the days of incubation.

BOD water-quality testing, wastewater and effluent analysis, environmental monitoring, dissolved-oxygen studies, and municipal, industrial and aquaculture water labs, often for regulatory compliance. The 300 ml bottle is the standard format for the classic five-day BOD test.

A borosilicate 3.3 bottle with a flared mouth and a matched tapered (pennyhead) ground-glass stopper. Filling to overflowing and inserting the stopper leaves no air bubble; the flare holds a water seal around the stopper during incubation. Numbered sets keep each stopper with its bottle. Amber versions limit algal photosynthesis that would skew oxygen readings.

Fill completely and insert the stopper so no air is trapped — a single bubble invalidates the result — then add water to the flared seal cup before incubating at 20 °C. Keep each numbered stopper with its own bottle, as ground joints are matched. Use amber bottles or dark incubation to prevent light-driven oxygen production by algae.

Formed from borosilicate 3.3 with the flared mouth and tapered joint, then the joint and stopper are precision-ground to an airtight matched fit and the set is numbered. Annealed for stress relief. Joint fit and freedom from leaks are the critical checks for a test that depends on excluding air.