The number of cartridges used on each respirator. Respirators generally use 2 cartridges.

The linear flow rate through the cartridge(s) varies directly with the worker breathing rate. If you calculate this value, be sure and account for the number of cartridges. A typical value for a moderate workrate of 60 LPM with 2 cartridges is about 13 cm/second.

The manufacturer should have the following values available. If not, you can estimate or measure a value.

The carbon micropore volume. This is a measure of the air spaces within the sorbent and is determined experimentally for each type of sorbent. If not available, you may use a conservative value of 0.4 cm³/gram.

The weight of sorbent (activated charcoal) in a single cartridge. If not available, you can disassemble a respirator cartridge and weigh the sorbent. Note that there can be a significant variation in the amount of sorbent between cartridges (±30% or more). If an average value is not available, you should adjust the weight toward the low end of the expected range.

The bulk density of the backed bed in units of grams per cubic centimeter. You can measure this by disassembling a respirator cartridge and determining the total volume (cubic centimeters) of the bed, then dividing this number into the sorbent weight (previous value). A typical value is about 0.4 grams/cm³.

You must provide the following information if you want the calculator to estimate the above values. The cartridge diameter assumes a round cartridge. If it is not round, you will need to determine the bed area and enter that value.