| ATI http://www.quantumanalytical.com/ Manufacturer of instrumentation including sensors and isolated two-wire transmitters for pH, ORP, dissolved oxygen and conductivity. | |
| ATEQ http://www.ateq.ca/ Produces leak and flow detectors with local calibration, service and support. | |
| ASM GmbH http://www.asm-sensor.com/ Manufacturing of sensors and measuring instruments including thermometers and recorderscopes. Headquartered in Germany. | |
| AMRA http://www.amra.be/ Portable instruments and transmitters for temperature, pressure and humidity including a line of panel meters and data loggers. | |
| AMETEK http://www.ametek.com/ A Global manufacture of electric motors and electronic instruments. | |
