Bed line/ bedline, adsorbent chamber

Слова встречаются в следующем контексте:

External Piping Volume is defined to be from the face of the external flange on the Adsorbent Chamber distributor nozzle to the flanged fitting of the Rotary Valve. For bed lines 1 and 13 the external volume is from the junction with the Adsorbent Chamber circulation line to the flanged fitting on the Rotary Valve.

Заранее благодарю!