美国Greyline
美国GREYLINE公司是一家致力于超声波测量技术应用的公司，其产品有多普勒超声波流量计、时差超声波流量计、明渠超声波流量计、超声波液位计、超声波液位差计。GREYLINE公司在美国和加拿大都设有工厂，销售网络遍布全球各地。
We develop and manufacture industrial flow and level monitoring instruments for measurement and control in water and wastewater treatment, industrial process automation and for environmental monitoring.
Greyline Level instruments include ultrasonic level transmitters, pump station controllers, tank farm monitoring systems, software and data loggers.

Greyline's ultrasonic Flow products include portable meters for troubleshooting and surveys, Doppler flow meters with strap-on sensors, flow switches, open channel and area-velocity flow monitors.