Hach CL17sc Colorimetric Chlorine Analyzer

Overview

The Hach CL17sc is an online colorimetric analyzer for free or total residual chlorine, built on the long service record of the original Hach CL17. Hach redesigned it to cut routine maintenance time and to add diagnostics and connectivity: it now has a flow meter, a colorimeter window, a multi-colour status light, predictive diagnostic software and simplified tubing replacement. The instrument measures 0 to 10 mg/L chlorine with a lower limit of detection of 0.03 mg/L and produces a new result every 2.5 minutes.

Seven Star LLC supplies the Hach CL17sc to water utilities, desalination plants, district cooling operators, food and beverage producers and power stations in the Sultanate of Oman and the GCC. Our Muscat engineers help you pick the free or total chlorine reagent set, the standpipe or pressure regulator installation kit, and the SC controller that will power the analyzer.

Measurement Principle of the Hach CL17sc

The Hach CL17sc has three working parts: a linear peristaltic pump that meters sample and reagents precisely, a colorimeter, and the indicator and buffer solutions. At the start of every cycle the analyzer measures the blank absorbance of the sample, which compensates for any natural colour or turbidity before chlorine is measured. Indicator and buffer are then added while a magnetic stirrer mixes the cell and the sample develops a colour proportional to the chlorine present.

The colorimeter measures light transmitted through the coloured sample using an LED at 510 nm over a 1 cm path, and compares the colour intensity with a reference. The cell is then flushed with fresh sample so the cycle can repeat every 2.5 minutes. Hach states that the analyzer is compliant with US EPA regulation 40 CFR 141.74, and that both Method 4500-Cl G and Method 334.0 can be used for residual chlorine in drinking water. Other oxidants such as bromide, chlorine dioxide, permanganate and ozone give a positive interference, and hardness must not exceed 1,000 mg/L as CaCO₃.

Engineering Design of the Hach CL17sc

The analyzer is wall mounted with four ¼-inch screws inside an IP66 enclosure measuring 342 x 329 x 177 mm and weighing 4.1 kg. Sample enters through a ¼-inch OD polyethylene tube with a quick-disconnect fitting and drains through a ½-inch ID flexible hose. Inlet pressure is 0.3 to 5.2 bar to the Y-strainer, which has a 40-mesh or finer screen, and 0.1 to 0.3 bar at the analyzer itself, with a sample flow of 60 to 200 mL/min. An optional air purge with a 3/8-inch quick-connect fitting is available.

The Hach CL17sc takes 12 VDC, 400 mA maximum, from a Hach SC controller through a cable about 6.5 ft long, so the controller and analyzer are normally mounted side by side. Reagent use is 0.5 L of buffer and 0.5 L of indicator in 31 days. Pairing the analyzer with an SC controller adds internal data logging, analog and digital outputs and the option to run a second parameter from the same panel position.

Key Features of the Hach CL17sc

According to the Hach datasheet, the Hach CL17sc offers the following.

• Free or total residual chlorine measurement from 0 to 10 mg/L with a 0.03 mg/L limit of detection.
• Accuracy of ±5% or ±0.04 mg/L, whichever is greater, from 0 to 5 mg/L, and ±10% from 5 to 10 mg/L.
• A 2.5-minute measurement cycle with automatic blank correction for sample colour and turbidity.
• Programmable maintenance alerts and step-by-step on-screen maintenance instructions.
• A built-in flow meter, colorimeter window and multi-colour status light for at-a-glance health checks.
• Simplified, pre-assembled tubing replacement through the CL17sc tubing kit.
• Monthly reagent consumption of 0.5 L buffer and 0.5 L indicator.
• Connection to Hach Claros on Claros-enabled controllers for remote instrument and data management.

Industrial Applications

Hach lists drinking water, wastewater, food and beverage, pharmaceutical, power generation, semiconductor and field use for the CL17sc. In Oman the most common duty is residual chlorine on treated water leaving desalination and groundwater plants, at reservoirs and pumping stations on the transmission network, and at the inlet of large consumers such as hospitals, hotels and airports. District cooling plants and industrial cooling towers also use the Hach CL17sc to keep biocide dosing within limits.

Food and beverage plants in Rusayl, Sohar and Salalah rely on chlorinated process water and need a verified record of residual levels, while wastewater plants check chlorine after disinfection before reuse or discharge. Seven Star LLC supplies the Hach CL17sc with engineering support in Muscat, along with reagent sets, tubing kits and calibration verification kits so the analyzer stays in service.

Technical Specifications

The data below are from Hach data sheet DOC053.53.35300 (December 2024) for the Hach CL17sc.

How to Order

To request a quotation for the Hach CL17sc, tell Seven Star LLC whether you measure free or total chlorine, your sample pressure at the Y-strainer, and which SC controller and outputs you need. We will confirm the order code and reagent sets, advise on stock and lead time for Oman and the GCC, and the Hach data sheet can be downloaded from this page. Related items include Hach DPD free chlorine reagent powder pillows for grab-sample checks, the Hach HQ4200 portable meter and the Hach 2100Q portable turbidimeter.

Controller and companion analyzer: Hach SC4500 controller and Hach TU5300sc laser turbidimeter.