Aqualytic AL400T-WL, Instruction Manual, Page: 8 / 32

8 AL400T-WL_2a 07/2011
1.1 General description
The AL400T-WL is designed to meet the criteria specified in U.S. EPA 180.1 on turbidity mea-
surement. The AL400T-WL allows for the measurement of turbidity in the field. The instrument
features auto ranging over the range of 0.01 to 1100 NTU/FNU.
The turbidimeter is supplied in a case complete with accessories and spares. The delivered
standards guarantee stable and reproducible results.
1.2 Operating principles
The instrument measures turbidity in the range 0.01 to 1100 NTU/FTU featuring auto ranging.
The light source is a tungsten lamp compliant with U.S. EPA 180.1.
The emitted light is reflected by turbidity
in the sample. The scattered light will be
detected at an angle of 90° by a photo-
diode.
This principle is part of ISO 7027.
The international Reference Standard
for turbidity is a Formazin solution. The
AL400T-WL is based on secondary stan-
dards which are a U.S. EPA approved
alternative standard to Formazin.
1.3 Factory calibration
The turbidimeter AL400T-WL is factory calibrated with secondary standards and does not
require user calibration before use. See chapter 2.3.2 User Calibration.