Nidek’s Nuvo Lite oxygen concentrator delivers precise and continuous delivery of oxygen at rates from 0.125 to 5 liter/min.

A more portable oxygen concentrator from Nidek Medical Inc, Birmingham, Ala. (nidekmedical.com) turns air into 95% pure oxygen for respiration. Conventional units weigh about 50 lb, but the new design weighs in at only 30, thanks in part to a custom directional control valve from Bosch Rexroth, Lexington, Ky., (boschrexroth-us.com/BRP). The valve outperformed several others, says Nidek New Product Development Engineer Gary McGaha, in its resistance to contamination and requirements for precise oxygen delivery and rapid cycling. (Air enters and oxygen exits about every 13 sec.) Off-the-shelf valves were too expensive.

The concentrator works by compressing room air and cooling it in a heat exchanger. One solenoid valve then directs the compressed air into one of two sieve beds or adsorbent columns. These adsorb nitrogen at pressure but let oxygen pass. So as one generates oxygen, the other purges trapped nitrogen from the previous cycle. Each column produces oxygen for about five seconds and delivers it to a storage tank.

The control valve delivers a precise amount of oxygen each cycle and works even if particles from molecular sieves enter the valve. Should the valve fail, the concentrator shuts down, forcing patients and clinicians to use backup oxygen supplies. “The Bosch Rexroth valve met all specs and it was the most reliable unit tested,” says McGaha.

The customized air valve from Rexroth meets Nidek’s requirements for size, weight, precise oxygen flow, cost, and reliability.