D&A Instrument Company

D&A Instrument Company*, located in Port Townsend, Washington, was a pioneer in their field by designing and manufacturing turbidity sensors as early as the 1980s. The company’s first marketed product was a simple, single-channel analog sensor, the OBS-1, based on backscatter technology. Over the years, D&A developed new sensors to replace existing sensors or to expand their product line. Their pioneering efforts contributed significantly to D&A Instrument Company becoming one of the most widely known names in the turbidity sensing field.

For many years, Campbell Scientific carried D&A Instrument Company’s OBS-3 and OBS-3+ sensors. These sensors were designed to monitor turbidity and suspended-sediment concentrations using optical backscatter (OBS) technology.

In November 2007, Campbell Scientific purchased the D&A Instrument Company’s OBS® line of turbidity sensors: the OBS-3+, OBS-3A, OBS-4, and OBS-5+. At the time of purchase, Campbell Scientific expressed its commitment to carrying on the tradition of high-quality craftsmanship that D&A had established. Campbell Scientific maintained a relationship with John Downing, the former president of D&A, for product consultation.

Production of the OBS sensors and all of the business operations were moved to Campbell Scientific’s headquarters in Logan, Utah, and remain in operation today. Campbell Scientific has a complete line of turbidity sensors using OBS® technology for your consideration and selection.

*The company has also been referred to as D&A Instruments.