Sash Chain and Cord
Selecting Sash Chain
The higher initial cost of sash chain, compared to sash cord, is offset by the chain's longer useful life. Chain should be selected for material, load rating and size.
Material
Sash chain is available in bronze and, to a limited extent, brass and stainless steel. Plain steel or copper coated steel chain should be avoided in high quality applications, as it will rust over time.
Load Rating
A sash weighing thirty pounds will place a static load of fifteen pounds on each of the two sash chains that suspend it. Suddenly raising, lowering or stopping the travel of the sash, however, will create an instantaneous load exceeding the normal static load by many times. For this reason, it is advisable to select chain with the highest load-rating capacity whose width will fit the pulley wheel groove.
Size
Sash chain is manufactured in trade sizes determined by width, links per foot and gauge of material. As stated above, chain should be selected for the maximum load-carrying capacity that will fit the pulley groove.
Estimating Length
For double-hung windows, the approximate total required amount of chain can be calculated by the following formula: (1/2 the sash opening height + 2 feet) x 4.
Additional Articles and Useful Information
Weight and Balance Systems for Wood Windows Design issues of the weight and pulley system are dicussed in detail ... read
Weight and Pulley Design Checklist and Calculation Examples A worksheet to assist in designing a weight and pulley system for wood windows. Includes two examples showing calculations for a typical system ... read